# Sky Energy TK90AHA test 0.35/wh LiFePO



## Technologic (Jul 20, 2008)

Ok this is the test thread for the battery I bought.

Right off the bat it appears I overcharged it for roughly 30 minutes. No swelling occurred but I'm attempting to try and understand the current voltage drop from my discharging. I believe I possibly damaged it permanently via overcharging, but so far I'm not sure if the 2.74v discharge at 10a right now is damage, needs recharging due to overcharging, or really the voltage drop

















As you can see the charging for over 4 hours at 4.1v x 10 amps... this is the most I could constantly pull out of my DC supply without the voltage bouncing around.

Discharge charts will be up in a few hours once the testing is completed... Results are not looking so great at 0.25C as far as voltage drop

As I posted yesterday... the voltage drop is significant even when only draining at 10 amps of current out.... this is PRIOR to the overcharging sin I committed (battery was charged to about 20% capacity at this point)


----------



## Technologic (Jul 20, 2008)

The battery is now discharged around 30AH... here's the chart (there was a 20A test that I stopped because he looked like it was going to be inaccurate)

Voltage has been consistent... voltage without a load is 3.44v.

At the moment I am simply attempting to drain the battery to recharge hoping the battery is made well enough 30 minutes of overcharging at 10a doesn't kill it. The battery's voltage was 4.17v before discharging began... it dropped very quickly to the 2.9v level during discharging

Ignore the jumps back up to rest voltage... these are me pausing it to adjust the terminals (as you can see the CBAII is not infinitely accurate voltage wise):


----------



## speculawyer (Feb 10, 2009)

Technologic said:


> Right off the bat it appears I overcharged it for roughly 30 minutes. No swelling occurred but I'm attempting to try and understand the current voltage drop from my discharging. I believe I possibly damaged it permanently via overcharging,


Ack!  










Technologic said:


> As you can see the charging for over 4 hours at 4.1v x 10 amps... this is the most I could constantly pull out of my DC supply without the voltage bouncing around.


I'm still learning but I see 3.44 Volts for just under 3 hours. But perhaps that is the battery voltage not the charger voltage? I'm not following. 



Technologic said:


> As I posted yesterday... the voltage drop is significant even when only draining at 10 amps of current out.... this is PRIOR to the overcharging sin I committed (battery was charged to about 20% capacity at this point.


So it was crap before the overcharge? Well, 20% of capacity is pretty low, I would expect it to be down in the 2.something volt range at that state of charge.


----------



## Technologic (Jul 20, 2008)

speculawyer said:


> Ack!
> 
> 
> 
> ...


that is the battery's voltage, not the voltage from the DC supply... that's the battery's voltage changing over time (very slowly ... it ramps up to 4.2 volts very quickly once it reaches about 95%) ... I can't immediately access the saved chart I have where I charged it for over 250 minutes on the CBA... because I'm currently testing discharge I can't load it to show everyone... but just trust me it was over 4 hours 




> So it was crap before the overcharge? Well, 20% of capacity is pretty low, I would expect it to be down in the 2.something volt range at that state of charge.


I wouldn't say it's crap... I simply don't have enough data yet to make assumptions. The only thing I'm attempting to get out of this test since I overcharged it... is the total Amp-hours the battery has charged... if that ends up being really close to 90AH... then I will worry about voltage drop in following (much more closely monitored) charging sessions.

30 minutes of overcharging on Lifepo should not damage the battery... just so we're clear, but it might damage my abilities to test nominal voltage for this run. Voltage wise it seems OK that the nominal voltage is 3.4v and I'm discharging at 2.8-2.9v... it's not terrible... and to be expected until I get a good charging cycle out 

One thing for sure is, lifepos are clearly not meant to be power dumped (at least this one)... voltage drop is substantial and sustained

Also it should be noted that this voltage drop could also possibly not even exist... the CBAII was not designed for high amperage discharges (has 12 gauge leads hard wired to it... they do get warm during testing). So far I've drained roughly 25 amp-hours out of the cell... it is staying at a very stable 2.9v (once I got the connections on there nicely)

Further tests will be able to verify... but applications where a constant 1-2C out of a pack is necessary probably shouldn't be looking to prismatic cells. Even at 20% capacity (and no overcharging) it was clear that had I dumped 90-150Amps out of this battery, it would have dropped below 2.5v

I almost forsee a "nominal discharge rate" of something like 0.3CA... which DOES vaguely follow many chinese lifepo suggestions


----------



## Technologic (Jul 20, 2008)

Ok here is the charging for over 4 hours (2 hours of charging prior to this wasn't saved). This is the voltage of the battery over time





This is the discharge... the battery has now drained 46.7AH from the initial start of testing. I intend to double the C rating discharge for the remainder. More to come.


----------



## Technologic (Jul 20, 2008)

Ok, terminals were becoming too hot to sustain the draw for a significant amount of time. Will probably need to go and trim the wires down solder larger gauges and make hard post terminals.

1 foot of this 12 gauge wire they use isn't cutting it (I want to test up to 40A next charging)

Here is the voltage drop from 3.3v nominal at 20A of draw (holding steady at 2.61v):


----------



## Tesseract (Sep 27, 2008)

Technologic said:


> ...
> One thing for sure is, lifepos are clearly not meant to be power dumped (at least this one)... voltage drop is substantial and sustained...


Hmmm... a 40A max load tester is not going to stress a 90Ah battery/cell enough to give useful data.

Furthermore, the whole point with LiFePO4 chemistry is to sacrifice some energy density for a much higher peak current capability, so these cells, if they truly are Lithium-Iron Phosphate chemistry, should be more than happy to dump power at a 3C or higher rate with little voltage sag.

I'm withholding judgment for now as it is entirely possible (but not likely) that you damaged the cell-under-test with that minor bit of overcharge (~ 5.6%), but for now it looks like the cells are NOT LiFePO4 chemistry or they are suffering from the "AA cell wrapped in a D cell body" syndrome... Not that a Chinese manufacturer would *ever* inflate their specs...


----------



## Technologic (Jul 20, 2008)

Tesseract said:


> Hmmm... a 40A max load tester is not going to stress a 90Ah battery/cell enough to give useful data.
> 
> Furthermore, the whole point with LiFePO4 chemistry is to sacrifice some energy density for a much higher peak current capability, so these cells, if they truly are Lithium-Iron Phosphate chemistry, should be more than happy to dump power at a 3C or higher rate with little voltage sag.
> 
> I'm withholding judgment for now as it is entirely possible (but not likely) that you damaged the cell-under-test with that minor bit of overcharge (~ 5.6%), but for now it looks like the cells are NOT LiFePO4 chemistry or they are suffering from the "AA cell wrapped in a D cell body" syndrome... Not that a Chinese manufacturer would *ever* inflate their specs...


40A max load tester is fine for my application... Not to mention I can manually test anything further via a dummy load resistor (of which I have many to choose from).

It's entirely possible overcharging did something permanent, but very very unlikely unless the chemistry isn't LiFePO. 30 minutes is the max it was overcharging for... the time I took a shower, but it wasn't showing even 3.9v by the time I got in, so... again... unlikely it was even 30 minutes.

as you can tell though, initial testing prior to overcharging showed similar voltage sage proportions (and in this case proportions are all that matters). 

Further tests will reveal what's going on. Overcharging lifepo's at all should only yield a overall drop in lifecycle as seen from a lower nominal voltage... that's really not what I measured at all (after letting the battery sit for 4-6 hours it still was at 4.15v prior to discharging).

Higher C rating isn't the reason I want lifepo btw... it's far lighter and less baby sitting than LiCoO2.

In general though, it's best to wait and see how subsequent cycles go I guess... reality is that there's no battery analyzer less than $4000 that can test 270amps and computerize the outputs... so I'm stuck with a max 0.5C test... hopefully with subsequent recharges it normalizes near the graphs the company posts (and Thundersky posts)

There's still the possibility that the leads from the CBAII are causing extra resistance via bad connections (though... still unlikely)... this would show as a voltage drop


----------



## ElectriCar (Jun 15, 2008)

You're planning on how many strings of these? Just curious how many amps you're planning to pull off your pack. My truck will draw over 400A with a fairly easy start until the rotor gets going and I know you've got in mind your super low cg creation with minimal weight but still, it will take some amps to get it moving, way more than 40 I'm sure.

Clue us in on your goals for this thread...


----------



## Technologic (Jul 20, 2008)

ElectriCar said:


> You're planning on how many strings of these? Just curious how many amps you're planning to pull off your pack. My truck will draw over 400A with a fairly easy start until the rotor gets going and I know you've got in mind your super low cg creation with minimal weight but still, it will take some amps to get it moving, way more than 40 I'm sure.
> 
> Clue us in on your goals for this thread...


No plans as of yet... the batteries are currently not useable from this test data under any circumstances.

I'm hoping the data for discharging is anomalous and after this charge cycle testing will normalize at something more acceptable (with a 1-2C range without much drop).

At the moment there's no way I'd purchase these batteries giving this kind of voltage drop... however the next test might be different.

I'm contemplating a parallel/series 60AH now actually... to cut down on loss of range through higher C pulls (even from really good lithiums) to do a 120AH x 106v or so set up... with whatever I choose. Hoping to not pull more than 60Amps off that pack sustained at highway or constant speeds (6kwh/hour tops).

My goals here are just to inform people as I test... that's it

I have no interest in pushing these batteries onto anyone... or even myself . I bought a sample to test as well as I could...


----------



## Technologic (Jul 20, 2008)

It appears that I was correct... the battery was merely giving false readings because of the overcharging...

recharging it is giving much more favorable results so far 

0.25C discharge is showing 3.24v sustained (after dropping from 3.4v)



Here is the graph so far... I'm not prepared to say anything substantive yet... we'll see... but I shortened the leads by a lot and directly attached it to the terminals

Battery was only charged maybe 70-80%... we'll see where it goes.

Looking very positive.


----------



## ElectriCar (Jun 15, 2008)

Ever hear of Nichrome wire? You can rig up a resistive load with it to test higher current discharges. Wind it around a non conductive form that won't burn or use glass bottles or such and play with that. Just a thought but not thought out! It's bed time...


----------



## JonasMeyer (Feb 28, 2009)

I also wouldn't discount the fact that those leads might be hurting things a little bit also. If they are heating up, then there is energy being outputted there. You basically made them into a small heater, and heaters as we all know are pretty wattage hungry. As for the anodized terminals, shouldn't it be possible just to scratch it off in the right places with a knife before you put the leads on?


----------



## Technologic (Jul 20, 2008)

ElectriCar said:


> Ever hear of Nichrome wire? You can rig up a resistive load with it to test higher current discharges. Wind it around a non conductive form that won't burn or use glass bottles or such and play with that. Just a thought but not thought out! It's bed time...


Yeah I have a 4ohm 400w resistors though... 8 ohm 2 ohms etc from years ago (with heatsinks I can rig up a fan on).

Resistive wires (heating elements) is another alternative...


----------



## Technologic (Jul 20, 2008)

JonasMeyer said:


> I also wouldn't discount the fact that those leads might be hurting things a little bit also. If they are heating up, then there is energy being outputted there. You basically made them into a small heater, and heaters as we all know are pretty wattage hungry. As for the anodized terminals, shouldn't it be possible just to scratch it off in the right places with a knife before you put the leads on?



I think between that and discharging the overcharge has helped... the load has stabilized dramatically this test run (far more than I predicted was possible)... at max testing output for the CBAII with this fuse in it (25A fuse... there's a 40A one that's swappable in)... with a bit of math I can use the CBAII to test any resistor load and figure out the output


----------



## david85 (Nov 12, 2007)

Sorry, Technologic. I didn't realize you already started your testing thread. Better late than never.

12 gauge wire is certainly part of the problem. I got some funny readings with my tests as well even a slightly loose terminal that was barely warm to the touch was enough to drop the voltage by about 3%. If its actually producing heat off the wires, then there is likely to be considerable voltage loss there.

I think your results are comming in fairly clean now. Your discharge curve looks exactly like my spreadsheet plot for my 0.33C results.

If you can't get any heavier wire, even doubling up on the leads with the size you have will help.


----------



## peggus (Feb 18, 2008)

Your leads are definitely your problem, it is obvious as you get different voltage drop every time you adjust the terminals. Also you should be using crimped on eylets bolted to the terminals, alligator clips won't do for this. Since the CBA does not have any sense leads I would oversize the wiring as much as possible to reduce the IR induced error.


----------



## Technologic (Jul 20, 2008)

david85 said:


> Sorry, Technologic. I didn't realize you already started your testing thread. Better late than never.
> 
> 12 gauge wire is certainly part of the problem. I got some funny readings with my tests as well even a slightly loose terminal that was barely warm to the touch was enough to drop the voltage by about 3%. If its actually producing heat off the wires, then there is likely to be considerable voltage loss there.


Yeah the 12 gauge certainly had me wondering as well. After shortening them and recharging the problem disappeared almost entirely.

Going to rig up some something like a heating element or if one of my dummy resistors works that will be more stable in order to give at least a 1C chart so we can proportionally figure out voltage sag when drawing it's rated AH capacity.

Here is the second charge... as you can see it's much more linear than the first:




Here is the Discharge at 23A (slightly over 0.25C) battery was only charged about 70% to full capacity.



As you can see it models for the first half or so at around 3.2v before dropping over somewhat sharply.

5 minutes after the test the voltage of the cell is 3.29v


----------



## Technologic (Jul 20, 2008)

peggus said:


> Your leads are definitely your problem, it is obvious as you get different voltage drop every time you adjust the terminals. Also you should be using crimped on eylets bolted to the terminals, alligator clips won't do for this. Since the CBA does not have any sense leads I would oversize the wiring as much as possible to reduce the IR induced error.


Eyelets work fine for the negative, but the anodization makes it an issue for the positive... which caused a bit of an problem. I need more tools (I'm still in my apartment at my law school right now)

I wish I could swap out the wire gauge, but as I said the 12 gauge leads were hard wired into the CBAII so I'll have to look at it later and see if I can resolder them to the board or something with 10gauge or so...

For now what I did was tighten the bolt heads and flatten out large portions of the bare wire onto the post itself.

Eyelets just weren't doing it (but I might not have had properly thick ones here.

Suffice to say I got it to work much better... I'll keep trying to improve testing accuracy.


----------



## speculawyer (Feb 10, 2009)

Definitely looking much better.

Looking pretty good for such an inexpensive battery. Man that Carnegie-Mellon paper dissing EVs is looking pretty stupid with their assumption of $1000/Kwh for batteries now.


----------



## Technologic (Jul 20, 2008)

speculawyer said:


> Definitely looking much better.
> 
> Looking pretty good for such an inexpensive battery. Man that Carnegie-Mellon paper dissing EVs is looking pretty stupid with their assumption of $1000/Kwh for batteries now.


Certainly looking better at 0.25C... I want to see 0.5C on the CBA though... with proper idealized thick copper connections...

The chart seems to match more closely with Thundersky's than it does with Sky Energy's. The battery had 10AH or so more useable output but at 2.97v I just decided to cut it off there and reset the charging (just to save time).

As you can see there was still about 1-2 hours left on the charging block to get it to full capacity at 4.2v (but you have to charge it at 4.2v for 60 minutes at 0.1C to finish charging )

I still say if voltage sag stays above 3.0v for the majority of the very high C tests we'd be in a very good situation ... at roughly $350/kwh (only $100/kwh more than GM is claiming they will get the Chevy Volt's battery for in massive volume)


----------



## david85 (Nov 12, 2007)

This is looking a *lot* better. That looks like almost every other LiFePO4 discharge curve I have seen (including my own). The curve should be slightly more flat before dropping off, but I have a feeling that with more cycling it will stabize a bit and hold higher voltage for a little longer before dropping off.

Notice how quickly the voltage rises at the end of the recharge curve. This is where a lot of discretion comes into play in tuning the charger. Supposedly you can push the voltage close to 10V before the cell will fail instantly, but the actual energy storage will not be much more than 3.7V. I find it curious that different manufacturers rate the top voltage cut off slightly differently. I wonder if this is one of the last frontiers of this battery chemsitry (finding the ideal top cut off voltage). 

10V will kill it, but will 4V hurt it? I wonder where the best compromise is...... Don't mind me, I'm just thinking out loud lol.


Technologic, you should get some sleep, it must be 3:00 AM over there.


----------



## speculawyer (Feb 10, 2009)

Technologic said:


> I still say if voltage sag stays above 3.0v for the majority of the very high C tests we'd be in a very good situation ... at roughly $350/kwh *(only $100/kwh more than GM is claiming they will get the Chevy Volt's battery for in massive volume*)


What? I don't think they've given a price . . . and it is surely more than $250. But I guess they have stated that they expect prices to drop . . . but that is just hope.


----------



## Technologic (Jul 20, 2008)

speculawyer said:


> What? I don't think they've given a price . . . and it is surely more than $250. But I guess they have stated that they expect prices to drop . . . but that is just hope.


Hold on I'll link you 
http://endless-sphere.com/forums/viewtopic.php?f=14&t=8965

They're saying they hope it will be $250/kwh in volume I suppose.



> This is looking a *lot* better. That looks like almost every other LiFePO4 discharge curve I have seen (including my own). The curve should be slightly more flat before dropping off, but I have a feeling that with more cycling it will stabize a bit and hold higher voltage for a little longer before dropping off.


I'm hoping the curve flattens once I get it closer to a full charge... charging at 4.25v is what is recommended. I'm usually charging at 4.15v.

Cheers


----------



## speculawyer (Feb 10, 2009)

Technologic said:


> Hold on I'll link you
> http://endless-sphere.com/forums/viewtopic.php?f=14&t=8965
> 
> They're saying they hope it will be $250/kwh in volume I suppose.


Yep. I do like this more solid quote though:


> GM Vice President Global Program Management, wrote on the GM Fastlane Blog that the current cost of the Volt Li-ion packs is “many hundreds of dollars per kWh” lower than the $1,000 kWh figure used in the study.


Being conservative and using 200 as 'many hundreds', I think we can for sure say they are paying no more than $800/Kwh . . . and obviously mostly likely much lower than that. However, they are not buying from some random Chinese vendor, so they are certainly not down in the $300/Kwh range we see with these low-end units. So somewhere between those two I'd say.

I'm always interested in getting cost numbers since I'm always in an argument with a guy who keeps pushing the new lead-carbon technology. He keeps using $1333/Kwh as the cost of Li-Ions . . . an obviously ridiculous value used to push his biased pro lead-carbon technology viewpoint. I'm battery technology agnostic . . . I just want the best battery technology out there to advance and get cheaper so EVs become adopted on a wider scale.


----------



## david85 (Nov 12, 2007)

speculawyer said:


> I'm always interested in getting cost numbers since I'm always in an argument with a guy who keeps pushing the new lead-carbon technology. He keeps using $1333/Kwh as the cost of Li-Ions . . . an obviously ridiculous value used to push his biased pro lead-carbon technology viewpoint.


Yeah he's way off there. I personally paid way less then that on two orders for LiFePO4s.

There seems to be a protectionist movement growing against lithium batteries because frankly, american companies seem to be out classed by asian manufacturers (not that thats anything new). When you can't beat them, ban them.


----------



## TheSGC (Nov 15, 2007)

Subscribing, can't wait for more results! If these pan out, they will most likely be my next set of batteries after my Pb kicks the can.


----------



## JRP3 (Mar 7, 2008)

I hope these are for real and work out. I'm a bit concerned as they can't seem to make up their mind as to what their factory really looks like
















The first pic looks computer generated.


----------



## Technologic (Jul 20, 2008)

JRP3 said:


> I hope these are for real and work out. I'm a bit concerned as they can't seem to make up their mind as to what their factory really looks like
> The first pic looks computer generated.


I was told they have 3 factories in different provinces... which certainly seems to be the case... at least one of them is in shenzhen (based upon UPS records)

The place they sent the package from was in Louyang.


----------



## JRP3 (Mar 7, 2008)

I don't know where they are located in regards to Guangzhou but it might be worth trying to contact this guy


> if you guys can give me a little time i am in the
> process of negotiating with several companies for
> prices. i am hoping i can organize enough of us that
> want the li-ion to get a better price. i live in
> ...


http://www.nabble.com/Re:-Li-Ion-Batteries-p22364091.html


----------



## Technologic (Jul 20, 2008)

JRP3 said:


> I don't know where they are located in regards to Guangzhou but it might be worth trying to contact this guy


Guangzhou has some of the lowest provincial regulations in china... (ie. cheaper labor and few export tariffs).

http://www.paulnoll.com/China/Provinces/I-China-map.gif

As you can see Guangzhou (the Americanized name) butts up against Chongching (a huge city... 2nd or 3rd largest in china)

Louyang is way north on the coast.

China does not use any standardized western symbols like Japanese romanji so there's no strict translation.


----------



## Technologic (Jul 20, 2008)

*Charging/Discharge #3*

This charge I attempted to fully charge the cell, but wasn't able to as you can see. The DC supply either from internal resistance build up in the battery or something won't hold amperage at 4.0v+ once the battery reaches this level. It will drop to 1 amp then shut down. I can change this at a much higher amperage (like 5v) but for now I'm not going to risk it. What I really need is the ability to put 5-7amps at 3.9v through a lot of resistance for about 1 hour to complete the charge. My supply just won't do it ... 




Here's the discharge graph... last one that will be at 23a (next will be 39a or 40a). As you can see the rest voltage before starting was only 3.61v (it should be like 3.8-3.9... losing at least 15% capacity here). I went ahead and let this one go to 2.5v



I'm going to wait a bit on the full blown capacity tests simply because I don't want to needlessly overcharge it (with high voltage) yet until I test the other things people are interested in.


----------



## rmay635703 (Oct 23, 2008)

The best heavy duty variable resistor most of us have laying around are the cheapo 500amp battery dischargers (have a dial to control discharge rate)
I doubt you will pull 3.9v through a resistor at 5-7 amps unless the battery is near dead, I would guess a 6v 2 amp car battery charger run through a variable battery discharger (or a big pot) would get you your 5-7 amps but you would need to monitor voltage constantly and dial off as needed. (the charger is only as smart as you are)

I do the above to charge my 8v batteries with a 12v dumb charger, can also equalize cells that way.

Remember sometimes cheaper is better, at least for one or two closely monitored tests, lets keep em coming


----------



## Technologic (Jul 20, 2008)

rmay635703 said:


> Remember sometimes cheaper is better, at least for one or two closely monitored tests, lets keep em coming


Will do 

It's been too long since I really messed with circuit design and for whatever reason I'm still having a major brain problem remembering how to calculate voltage and amperage drop along a large resistor

I know it's R=V/I for Ohm's law... so for 3.4v and 90 amps, That means to have a 100% voltage drop/current drop I'd need a 0.04ohm resistor... so I want about 60% of that to be heated off (so I can read the 35 amps on my CBAII to graph 1C) so I'd want a 0.024ohm resistor (of course in the form of a Nichrome heating element).

I think that's correct... but I don't know... it's been over 3 years now since I last messed with light amplifier design
Meh that doesn't seem right... I should probably go to bed


----------



## JRP3 (Mar 7, 2008)

*Re: Charging/Discharge #3*



Technologic said:


> As you can see the rest voltage before starting was only 3.61v (it should be like 3.8-3.9... losing at least 15% capacity here).


On the graph it looks as if starting voltage was about 3.5?


----------



## Technologic (Jul 20, 2008)

*Re: Charging/Discharge #3*



JRP3 said:


> On the graph it looks as if starting voltage was about 3.5?


Yeah it's difficult to see because it dropped to 3.4 so quickly, but it was 3.61v ish 

Here's the data point


----------



## Powered By DC (Jan 3, 2009)

I have been using these cells for quite some time and can tell you that it is quite normal for them to drop to about 3.6v resting not 3.8-3.9 . You are not loosing any where near 15% of the capacity. They should be concidered fully charged at this point. Charging above 3.8 volts is almost usless you might gain an aditional AH from it. As soon as you apply a load the resting voltage quickly drops to 3.2-3.3v and will remain there until nearly depleated. It takes about 20 cycles before you will see the full capacity of the cells.

Dave Kois
Powered By DC, LLC
www.poweredbydc.com


----------



## Technologic (Jul 20, 2008)

Powered By DC said:


> I have been using these cells for quite some time and can tell you that it is quite normal for them to drop to about 3.6v resting not 3.8-3.9.http://www.poweredbydc.com


Can you provide any insight in to how the batteries are working for you?


----------



## Powered By DC (Jan 3, 2009)

The have been working great, I have not had any problems with them. The voltage does seem to sag more when it is cold (in the 30's or below) so if you plan on using them in a cold enviornment I would suggest having battery warmers in you boxes. Let me know if you have any specific questions.

Dave Kois
Powered By DC, LLC
www.poweredbydc.com


----------



## Technologic (Jul 20, 2008)

Powered By DC said:


> The have been working great, I have not had any problems with them. The voltage does seem to sag more when it is cold (in the 30's or below) so if you plan on using them in a cold enviornment I would suggest having battery warmers in you boxes. Let me know if you have any specific questions.
> http://www.poweredbydc.com


Good to know...
I plan to have a temp controlled battery box that keeps it at 50F in summer and winter... so they age super slowly.

Solar powered for that aspect as well.


----------



## ElectriCar (Jun 15, 2008)

Technologic said:


> Good to know...
> I plan to have a temp controlled battery box that keeps it at 50F in summer and winter... so they age super slowly.
> 
> Solar powered for that aspect as well.


What are you speaking of when you say "age"? Will they wear out faster if certain conditions are present?


----------



## Technologic (Jul 20, 2008)

ElectriCar said:


> What are you speaking of when you say "age"? Will they wear out faster if certain conditions are present?


Yeah they will.

Higher temps = higher rate of aging...

50F and less than a full charge is best to have them age only 2-3% per year.

Lower is better, but you lose discharging capacity some.

60C for instance the battery will lose like 80%/year


----------



## JRP3 (Mar 7, 2008)

Powered By DC said:


> I have been using these cells for quite some time and can tell you that it is quite normal for them to drop to about 3.6v resting not 3.8-3.9 .


I thought you were using TS cells, are you sure the Sky Energy cells are the exact same thing as the TS cells?


----------



## Powered By DC (Jan 3, 2009)

Yes, they are thundersky cells. TS is changing their name to increase their market share according to my supplier.

Dave Kois
Powered By DC, LLC
www.poweredbydc.com


----------



## JRP3 (Mar 7, 2008)

Interesting, that was certainly a suspicion.


----------



## Technologic (Jul 20, 2008)

*37A test (0.41C)*

This was the initial 37A discharge test of charge #4. Resting voltage was 3.81v before starting the test... it stopped early due to heat build up so I mounted another fan and finished the test



Second test after fan was added to battery analyzer.




As you can see the total discharge was lower... though the total charge appeared higher... I believe this was due simply to the CBAII being about 120F the entire test (despite two fans)

It appears an early drop off was due to the temperature (since this also heated the CBAII's wires)


----------



## Hondacrzy (Mar 15, 2008)

So how long was that final test at 37 amps total? It appears they are doing better as you cycle them. What amps did you charge at the last charge? What was the power supply you are using? 

Chris


----------



## Technologic (Jul 20, 2008)

Hondacrzy said:


> So how long was that final test at 37 amps total? It appears they are doing better as you cycle them. What amps did you charge at the last charge? What was the power supply you are using?
> 
> Chris


I'm using an old PSU that's adjustable from 3.5v-6v at 0-50amps (though it won't output 50 amps at all voltages and drops to about 15 amps during most charging due to resistance).

The cycle was maybe 2 hours at 37 amps... it is doing better, but that test was still only 65 amp-hours or so.

Higher C draw is less total useable power... but still 2.5v at 75 amp-hours like last time means about 83% of the pack is useable.

I'm hoping I can figure out a way in the next 1-2 days to do a 1C and/or a 2C test... with a load resistor in series.


----------



## Hondacrzy (Mar 15, 2008)

Does that power supply do a constant current or does it start out high and then drop as it charges? I am asking because I may be interested in ordering the 120AH or 160AH as a sample and I am looking for a power supply that will work. Do I need one that will do constant current? I emailed Ivy Energy for the prices.


----------



## Technologic (Jul 20, 2008)

Hondacrzy said:


> Does that power supply do a constant current or does it start out high and then drop as it charges?


current is constant for most of the charging, it just reduces once the battery is almost charged.


----------



## speculawyer (Feb 10, 2009)

So . . . any summary judgment at this point?


----------



## Technologic (Jul 20, 2008)

speculawyer said:


> So . . . any summary judgment at this point?


Battery is certainly looking positive... I still don't think it's fully charged yet, due to the general lack of time spent on the DC supply after it reaches 4 volts (usually only 5-7 min before the DC supply shuts off due to resistance). I'm attempting to try to fully charge the battery like the time I overcharged it when I discharged it 95AH

I want to get a 1C test to make sure the voltage drop is acceptable.

Hopefully the 80-85% DOD point will allow people to pull most of the 90AH out of the battery... 

voltage drop seems to be good though... so it certainly looks as to be expected for lifepo

The only problems I've had with the battery so far is the cheap posts... something that shouldn't be a problem with the free battery to battery wiring they do for packs...
Likewise a lot of downward pressure on the posts themselves has more than once made me worry the battery cell would fall into the case (though it never really dropped down... just was able to be pushed down somewhat)

Might be a tad nitpickey but I want to be as accurate as possible.

I certainly am somewhat worried about the 1C voltage drop and AH roll off though, so it's very necessary to test it


----------



## notnull (Jul 30, 2008)

Technologic,

I know it isn't polite to ask people about price, but I would really like to get some of the 160ah cells and I need to know the delivered price, not the quoted price per piece.

How many of the 90ah cells did you get and what is the total dollar figure to get them delivered to your door?

I would write a check for $800 in a heartbeat if I could get four of the 160ah batteries delivered to my door, but I don't think it is possible. My calculations say that 160ah * 12v = 1920 Wh for $800. This is about 42 cents per Wh, which is what I think you have quoted from some of these vendors, but is it really possible when you adding in shipping, etc.

Thanks,

Steve


----------



## Technologic (Jul 20, 2008)

notnull said:


> Technologic,
> 
> I know it isn't polite to ask people about price, but I would really like to get some of the 160ah cells and I need to know the delivered price, not the quoted price per piece.
> 
> How many of the 90ah cells did you get and what is the total dollar figure to get them delivered to your door?


1 cell was $175.98 delivered... this included 62.98 in shipping charges (1.25/AH is the rate for batteries less than a moderate quantity)



> I would write a check for $800 in a heartbeat if I could get four of the 160ah batteries delivered to my door, but I don't think it is possible. My calculations say that 160ah * 12v = 1920 Wh for $800. This is about 42 cents per Wh, which is what I think you have quoted from some of these vendors, but is it really possible when you adding in shipping, etc.
> 
> Thanks,
> 
> Steve


If you only need 4 batteries you could get them... the price will be $1.25/AH or $200 + shipping for each 160AH battery.

Assume $100-200 (you can source the shipping yourself and they will send it whatever method you perscribe) for shipping by air of 4 batteries... they will weigh about 20kg so.

By boat you can do it for about $100 shipping easily.

Your call... The price increases to $1.25/AH for samples less than any serious order size (I assume they're making about 30% profit on this number)

Also as you can see by the graphs... it's closer to 12.8v average for discharging (higher and lower respectively at full and close to discharged)... or 2048WH for $900 or so dollars... feel free to include your order with mine though! (though I'm not sure when you need them) I intend to get 160AHs now.

You could get them for $800 delivered if added on to my order (since it'll be at a $1.1/AH price + bulk freight shipping) just need to wait anywhere between 2-4 months (not trying to convince you to do this at all, just one option).

On your own though it'll be between $900-1000 shipped for that quantity direct


----------



## JRP3 (Mar 7, 2008)

Somewhere I saw a quote of about $20 per battery for shipping larger orders from Sky Energy, I think that was for 60ah cells. Pretty sure that was NOT air freight at that price.


----------



## Technologic (Jul 20, 2008)

JRP3 said:


> Somewhere I saw a quote of about $20 per battery for shipping larger orders from Sky Energy, I think that was for 60ah cells. Pretty sure that was NOT air freight at that price.



I've shipped 100lb-150lb packages by sea from china for $180 before (also rather large packages in volume that weighed that much).

I think it just depends on which service you're using

$20/battery isn't impossible from air... or partial air (air from china, ground in the US).


----------



## notnull (Jul 30, 2008)

Thanks, that is exactly what I wanted to know.

I am planning on putting together a 12V module using four of the 160ah batteries and then adding it in series to my 120V pack of AGM batteries. Then I can get some real world testing done using the vehicle I drive every day. Not sure when I will be ready to order, I am still considering some of the more expensive cells like A123, PSI, Headway, etc.

Steve


----------



## Hondacrzy (Mar 15, 2008)

I asked for a quote for shipping to the USA for 40 cells and Sky Energy gave me a quote of $900 . I hope someone has better conections than that. I also received a quote for the 120V BSM and they said it would be $1200 for a 120v pack. It appears to be the same one Elite Power solutions offers.
http://elitepowersolutions.com/products/product_info.php?cPath=6&products_id=49


----------



## JRP3 (Mar 7, 2008)

What size cells was that for, and was that by air or boat? That's in line with the $20 per cell someone else was quoted.


----------



## Technologic (Jul 20, 2008)

Hondacrzy said:


> I asked for a quote for shipping to the USA for 40 cells and Sky Energy gave me a quote of $900 . I hope someone has better conections than that. I also received a quote for the 120V BSM and they said it would be $1200 for a 120v pack. It appears to be the same one Elite Power solutions offers.
> http://elitepowersolutions.com/products/product_info.php?cPath=6&products_id=49


lol that's a bit on the high side for shipping.

Likewise that BMS is grossly higher than what I was quoted, but I was asking about 50 cells of 60AH batteries.

Interesting...


----------



## Hondacrzy (Mar 15, 2008)

JRP3 said:


> What size cells was that for, and was that by air or boat? That's in line with the $20 per cell someone else was quoted.


That was slow boat. I did not specify the 120AH or 160AH. The shipping for one sample cell by air is $80. My Kelly controller cost me $50 shipping and took about 7 days . Not sure about where Kelly is are compaired to Sky.


----------



## dimitri (May 16, 2008)

$900 shipping from China is not bad considering weight and volume of a 40 cell pack of 160Ah or similar. Was that $900 to the closest sea port or to your door? What about customs fees, taxes, etc?

I paid $500 domestic shipping from Elite Power in Arizona to my home in Florida, that's how much Yellow truck shipping costs these days. The package is a pallet of 3 large wooden boxes, filled with lots of foam packing to protect the batteries, whole thing was pretty impressive in size and weight, so consider that when planning your purchase.

EDIT: just looked at the packing slip from Yellow, it was total of 675 Lbs. So overseas shipping of $900 is actually pretty cheap considering $1.30/Lb. If that is to your door, then its a steal, but I doubt it, its more likely to the closest sea port.


----------



## Technologic (Jul 20, 2008)

dimitri said:


> $900 shipping from China is not bad considering weight and volume of a 40 cell pack of 160Ah or similar. Was that $900 to the closest sea port or to your door? What about customs fees, taxes, etc?


Assume that it landing in port is only $2000 for a 40 ft container full of goods

This was the price I was quoted out of Chongching last year to land in Charleston, SC (where I can easily pick it up myself).

On that scale 200lbs of batteries would cost $100-200 at port tops (and that's quite a bit)


----------



## dimitri (May 16, 2008)

Technologic said:


> Assume that it landing in port is only $2000 for a 40 ft container full of goods
> 
> This was the price I was quoted out of Chongching last year to land in Charleston, SC (where I can easily pick it up myself).
> 
> On that scale 200lbs of batteries would cost $100-200 at port tops (and that's quite a bit)


That would be true if you bought whole container of batteries, which is how US resellers can make any money, buying in bulk. But for individual buyer looking for 40 cells total shipping cost will be much higher, especially for those far from the sea ports. I seriously considered this fact when I planned my purchase and buying from Elite suddenly didn't seem like a bad idea


----------



## Technologic (Jul 20, 2008)

dimitri said:


> That would be true if you bought whole container of batteries, which is how US resellers can make any money, buying in bulk. But for individual buyer looking for 40 cells total shipping cost will be much higher, especially for those far from the sea ports. I seriously considered this fact when I planned my purchase and buying from Elite suddenly didn't seem like a bad idea


You can split a 20 ft container though, there are services that do it actually...

Though the non-close to port people might have issues, I'm sure I can find a much cheaper price out of louyang than $900... louyang isn't an inner province (it's coastal).

Again I will be surprised if I can't... but we'll see once I get more information from them soon.


----------



## david85 (Nov 12, 2007)

Shipping for my 144V/200Ah battery/charger and BMS was $300 if I remember right. (less than air freight of the sample)


----------



## Technologic (Jul 20, 2008)

david85 said:


> Shipping for my 144V/200Ah battery/charger and BMS was $300 if I remember right. (less than air freight of the sample)


sounds about right David, thanks for clarifying though


----------



## dimitri (May 16, 2008)

david85 said:


> Shipping for my 144V/200Ah battery/charger and BMS was $300 if I remember right. (less than air freight of the sample)


 That is simply incredible. I wonder how they manage it. They must recoup some portion of the freight from the battery price, so they don't scare off the customer with high freight cost.

Every quote I got from China had significant freight cost...


----------



## Technologic (Jul 20, 2008)

dimitri said:


> That is simply incredible. I wonder how they manage it. They must recoup some portion of the freight from the battery price, so they don't scare off the customer with high freight cost.
> 
> Every quote I got from China had significant freight cost...


Battery manufacturers aren't the only companies in china. In my dealings with other companies, sea freight of even large volume/weight goods is usually pretty minimal.

It's possible that instead, the lower priced battery manufacturers are attempting to recoup the costs of the battery from the shipping on smaller orders.

I doubt it's that simple though, more likely the companies you asked just didn't really look around for it much...

They either deal in full trailers or air shipping most of the time I'm sure.

I've calculated a lot of freight shipping from NC to Uruguay, Argentina etc (much less volume than china as you can imagine)... goods are usually never more than $300 no matter how much weight as long as the volume is something decently small (which it def is in this case).

I sent a 150lb 60" plasma TV to Uruguay for $228 and something about a year ago. (5200 mile trip by air) Took 28 days by ship though

I emailed my contact about this, to get a quotation of sea shipment to the port in SC.

That certainly will give some of us near ports options.


----------



## david85 (Nov 12, 2007)

I would call it reasonable, not incredible

Shipping by sea is cheaper than dirt and by all rights should be priced as such. Simply having it trucked from the sea port to out shop was close to another $300 with a shipper that we have used for many years. Still not a bad price in my book.

If its being sent by air, then prices are going to be way higher (no pun intended).

I should also add that shipping rates have dropped a lot in recent months thanks to the world economic problems. Don't be afraid to drive a hard bargain.

I'm not sure, but perhaps the fact that I used the port of vancouver might have something to do with it. Its generally considered the gateway from the pacific rim to north america. I would expect rates to be competitive if for no other reason than how much stuff comes from asia to vancouver anyway.


----------



## Technologic (Jul 20, 2008)

From Sky Energy:

"60 pcs 90Ah battery and 2 pcs charger is 920 USD by sea"

pretty high 

$15.33/battery or 0.05/wh additional


----------



## JRP3 (Mar 7, 2008)

So lets take a penny off for the chargers and add at least one back in for the BMS system, though I think for most it will be much more than that, and our .35 wh is really at least .40 wh by the time you actually get the batteries, which isn't bad.


----------



## yamez4u (Feb 10, 2009)

I found this government test on similar batteries: http://www.osti.gov/bridge/servlets/purl/842964-8Ub23s/native/842964.pdf
Look really good even after 400 100% top to bottom cycles they still had 60% capacity! 
I'm pretty much sold just have to get an ideal of total cost now. Do you know if the cells your testing are the newer type with carbon coating?


----------



## Technologic (Jul 20, 2008)

yamez4u said:


> I found this government test on similar batteries: http://www.osti.gov/bridge/servlets/purl/842964-8Ub23s/native/842964.pdf
> Look really good even after 400 100% top to bottom cycles they still had 60% capacity!
> I'm pretty much sold just have to get an ideal of total cost now. Do you know if the cells your testing are the newer type with carbon coating?


I highly doubt they are.

Also that is a test of lithium-ion batteries I believe, hence the low cycle life...

The article is pretty badly written, so it's hard to tell what they're even testing. Certainly 400 cycles to 60% DOD would be a fairly horrific result. Those appear to be pouch type lithium polymers or pouch type Li-ions


----------



## yamez4u (Feb 10, 2009)

I read it very differently then you. To me they clearly state "low-cost LiFePO4-based high-power lithium-ion cells was investigated" And considering they ran them completely dry 400 times, I think it says good things about this chemistry. For your battery the stated 3000 cycle life is for 70% and 2000 cycle life for 80%. So lets extrapolate a little so then 1000 for 90% and then 500 cycle life for 100%. Which the paper seem to supported. But maybe I'm just missing what you where trying to say?


----------



## Technologic (Jul 20, 2008)

yamez4u said:


> I read it very differently then you. To me they clearly state "low-cost LiFePO4-based high-power lithium-ion cells was investigated" And considering they ran them completely dry 400 times, I think it says good things about this chemistry. For your battery the stated 3000 cycle life is for 70% and 2000 cycle life for 80%. So lets extrapolate a little so then 1000 for 90% and then 500 cycle life for 100%. Which the paper seem to supported. But maybe I'm just missing what you where trying to say?


I'm saying that LiFePO4 isn't lithium-ion (in any real marketing or actual sense), hence why the article is confusing.

Likewise the 400 cycles is not much proof. They used very small batteries (a few thousand mAH) which generally are made for lower life cycles. 

Draining lithium batteries past their 2.5v (or whatever max low voltage point) can severely damage them, and not linearly... so the measurement is somewhat problematic to prove anything (since the variable factor is so large).

The study was rather poorly done is my only point, I distrust the data points and 100% drainage points not damaging life cycle.

Clearly the carbon coated anodes would lower IR and increase cycle life, that's basic physics... just wondering why they rejected all sensibility with the prescribed treatment methods for lithium batteries, maybe they simply didn't want to test them for thousands of cycles. It's difficult to understand how they claim to be discharging them 100% (fully) and yet not showing any voltages past 2.5v on their discharge graphs (cut off?)

I'd love a battery testing center to buy up 3-5 batteries (whatever cell size works for them) from the top 10 cheapest worldwide manufacturers (Sky Energy, Ping, Seiden, etc) and test them at rated specs with a 1C discharge for 3000 cycles or more...

That data would be worth a published paper 

There's certainly a lot of RC guys reporting that their Lifepos are taking 4 digit cycles without much voltage drop... the large formats are all that matters though. Not trying to discourage you from sharing such papers, always interesting, just don't really understand that one too clearly.


----------



## JRP3 (Mar 7, 2008)

I can see 400 repeated cycles to 100% DOD at a high C rate giving a 60% capacity result being pretty good. I couldn't get the link to open for some reason so I didn't read the study but I don't think it's necessarily out of line for LiFePo cells. Worst case abusive testing is a good way to test a cell as it saves a lot of time and should give a reasonable picture of how a cell performs.


----------



## speculawyer (Feb 10, 2009)

Technologic said:


> I'm saying that LiFePO4 isn't lithium-ion (in any real marketing or actual sense), hence why the article is confusing.


I disagree. I believe that LiFePO4 (Lithium Iron Phosphate) are one particular chemistry in the general class of 'Lithium Ion' batteries. (LiFePO4 is a subset of the 'Lithium Ion' set that also includes Lithium-Cobalt, Lithium-Magnesium, Lithium-Titanium, and other Lithium Ion variants.)

However, I do think this terminology is now very unfortunate since many people now equate 'Lithium Ion battery' with 'exploding battery' these days due to the Lithium-Cobalt chemistry batteries that were prone to thermal runaway. Hence I like using 'LiFePO4' instead of 'Lithium Ion' to distinguish. But unfortunately too few people have any idea what LiFePO4 batteries are.


----------



## david85 (Nov 12, 2007)

Not that it really matters much, but you are both in a sense right.

L-Ion is generally used to describe the old spiral wound LiCO2 chemistry batteries, LiPo, for identical chemistry but with polymer separator barrier (prysmatic), and LiFePO4 used to describe the Iron phosphate chemistry.

Technically, they all use lithium and ions to perform the chemical reaction process, but generally, if you ask for Lion, you will get LiCO2. Since there seems to be a couple extra lithium battery chemistries unveiled every year now, simply calling them all lithium Ion can lead to confusion. 

Better to use the full name or chemical designation or you will be typing more trying to explain what you meant anyway.


----------



## speculawyer (Feb 10, 2009)

david85 said:


> L-Ion is generally used to describe the old spiral wound LiCO2 chemistry batteries, *LiPo*, for identical chemistry but with polymer separator barrier (prysmatic), and LiFePO4 used to describe the Iron phosphate chemistry.


Well done . . . you avoided another difficult confusing term . . . 'LiP' . . . some have used that for Lithium-Polymer and others have used it for 'Lithium Iron Phosphate'. 



> Technically, they all use lithium and ions to perform the chemical reaction process, but generally, if you ask for Lion, you will get LiCO2.


Exactly. And that is what I think is unfortunate. The generic class term 'Lithium Ion' is strongly associated with the first popular version of that class . . . the Lithium Cobalt. And due to the the thermal runaway issue, many people think exploding battery when they here 'Lithium Ion'. Thus, LiFePO4 has some work to do in getting rid of that taint.


----------



## JRP3 (Mar 7, 2008)

It's really not that hard to get around. When I say Lithium battery and people say "don't they explode", I just say no, it's a different, safer chemistry that doesn't explode. It's not a hard concept for most people to grasp even if they don't know the chemistry. Sometimes I start out with a preemptive strike and say "new non explosive" lithium chemistry


----------



## Hondacrzy (Mar 15, 2008)

Hey Tech, any more tests on the battery? Were you able to do a 1c test yet?


----------



## Technologic (Jul 20, 2008)

Hondacrzy said:


> Hey Tech, any more tests on the battery? Were you able to do a 1c test yet?


Not yet... I've had some real life issues recently that have kept me busy so I haven't been able to build any sort of inline resistor rig yet.

I can do additional tests, but that 1C test will probably be a bit away still. I may have time friday to get the additional materials I need... possibly this weekend.


----------



## Technologic (Jul 20, 2008)

In the last 24 hours I received a Revised quotation for shipping on the TK90AHA and have received a price of $440 for 70 pieces
or $6.20/each

So this is fairly viable option (that price is significantly lower than headway's for shipping as well).

Amazing what putting up a fight can do eh? 

At any rate I should have a 1C test in the next few days so anyone interested keep your eyes open... I've finally got some time as of tomorrow (done studying).

This leaves the shipped price at 0.365/wh...

I'm not sure if anything can even get within 10 cents of that right now.

(Headway's shipped price was 20 cents more/watt-hour for 1000 pcs).


----------



## ClintK (Apr 27, 2008)

Technologic said:


> This leaves the shipped price at 0.365/wh....


Every time I think "ok, still going with the cheaper lead acid, I'll get Lithiums on my next go", I see some ridiculous drop in price like that!


----------



## Technologic (Jul 20, 2008)

ClintK said:


> Every time I think "ok, still going with the cheaper lead acid, I'll get Lithiums on my next go", I see some ridiculous drop in price like that!


A few people have contacted me about doing orders together... I have no issue repackaging after picking them up and sending it out again... could be even cheaper that way.

At any rate you're right... the price is so low it's becoming that much more silly to contemplate Lead Acid.

1kwh costs a mere $365 to your door... that's almost the price of Trojan lead acids


----------



## ClintK (Apr 27, 2008)

Technologic said:


> A few people have contacted me about doing orders together... I have no issue repackaging after picking them up and sending it out again... could be even cheaper that way.


Where do you live? Shipping within the US is pretty pricey, but I guess your shipping from China may not differ much with an extra hundred pounds.


----------



## Technologic (Jul 20, 2008)

ClintK said:


> Where do you live? Shipping within the US is pretty pricey, but I guess your shipping from China may not differ much with an extra hundred pounds.


I live in NC and will be picking them up at a port directly.

Shipping to TX was already checked... for each order size (40 or so batteries) would cost about $180 additional... cheapest I could find for freight.

The shipping price would go up a bit... but each unit price would lower the more pieces to be sure.


----------



## judebert (Apr 16, 2008)

Of course, NC is a beautiful state, particularly in the Blue Ridge. And there's plenty of history to take in there. You could easily justify the cost of a car trip to NC for a short vacation and to pick up your new pack.


----------



## BWH (Sep 26, 2008)

judebert said:


> Of course, NC is a beautiful state, particularly in the Blue Ridge. And there's plenty of history to take in there. You could easily justify the cost of a car trip to NC for a short vacation and to pick up your new pack.



I'll gladly back that up. I've spend a few vacations at a cabin in Maggie Valley, NC. The Great Smoky Mountains National Park is worth the trip. 

I'd go back if I could afford the batteries.


----------



## JRP3 (Mar 7, 2008)

Probably would cost you more in gas than the shipping would be.


----------



## ClintK (Apr 27, 2008)

judebert said:


> Of course, NC is a beautiful state, particularly in the Blue Ridge. And there's plenty of history to take in there. You could easily justify the cost of a car trip to NC for a short vacation and to pick up your new pack.


4400 miles round trip from Phoenix... I'd have to ship it.


----------



## Camaro (Jul 29, 2008)

Tech,
 When do you think this group buy will happen? I'll be needing batteries soon, and I've convinced myself (and the wife) that I can't afford not to get LifePO's at 0.35/wh.
 One does have to consider the BMS and charger for a LifePO in the cost calculations. Does anyone know what is the cheapest 144V LifePO charger out there?


----------



## Technologic (Jul 20, 2008)

Camaro said:


> Tech,
> When do you think this group buy will happen? I'll be needing batteries soon, and I've convinced myself (and the wife) that I can't afford not to get LifePO's at 0.35/wh.


To answer each question in turn:
It will occur within 3-4 weeks tops... I need to settle things ( and get my tax returns back) but beyond that there's no delay at present, just finishing up some more tests.



> One does have to consider the BMS and charger for a LifePO in the cost calculations. Does anyone know what is the cheapest 144V LifePO charger out there?


The BMS I intend to use is the goodrum/fetcher BMS ... both due to price and it's currently the only autobalancing shut off protection for every cell BMS available.
http://visforvoltage.org/forum/5192-4-24cell-battery-management-system-bms

costs about $105 for a populated board (for 24 cells charging and discharging)... you can choose 2v or 2.7v low voltage cut offs depending what chip you buy.

Here's the charger I will probably be going with for $203:
http://www.bmsbattery.com/index.php...id=187&zenid=6a5968383c286a860b3bfbec251a74e1


----------



## JRP3 (Mar 7, 2008)

Have you checked out Brian's, (bblocher), Volt Blochers?
http://s2kev.blogspot.com/2009/03/volt-blocher.html


----------



## Camaro (Jul 29, 2008)

JRP3 said:


> Have you checked out Brian's, (bblocher), Volt Blochers?
> http://s2kev.blogspot.com/2009/03/volt-blocher.html


 
It's not a bad idea, but I like the BMS that Tech showed, as it actually cuts the voltage to the cell when the cell is fully charged, and it's cheaper. 
I like Blocher's build though, very clean!


----------



## Technologic (Jul 20, 2008)

JRP3 said:


> Have you checked out Brian's, (bblocher), Volt Blochers?
> http://s2kev.blogspot.com/2009/03/volt-blocher.html


Oh wow... way to go Brian  I've looked many times at his blog but not since he added the balancers

Simple design, but I like it none the less and for the price with no work... hard to beat it... it solves the issue of the fetcher cut off being 2.7v which is higher than the Sky Energy's actually need for optimal life cycle.

Though I'm a fan of it, it's designed for augmenting a "BMS/charger system" together... which is not what I will have if I'm buying those $203 chargers

I'm contemplating just designing my own circuit for the task... because I'm using regen (via sepex or AC motor of some sort) I'd like to have a LV cutoff, high voltage cut off.

The goodrum/fetcher has the distinct issue of not shunting enough current (only like 0.5A) during charging making it take forever to balance cells if one falls out of balance (in fact a 3% out of balance on a 160AH cell I believe can take upwards of 10 hours to completely balance that out).


----------



## RKM (Jun 9, 2008)

Camaro said:


> Tech,
> When do you think this group buy will happen? I'll be needing batteries soon, and I've convinced myself (and the wife) that I can't afford not to get LifePO's at 0.35/wh.
> One does have to consider the BMS and charger for a LifePO in the cost calculations. Does anyone know what is the cheapest 144V LifePO charger out there?


I'd like to have two sets of 45 X 160Ah batt packs for June 2 (my birthday!). Let's hope the testing goes well. What is the lead time once an order is placed?

Rob


----------



## Technologic (Jul 20, 2008)

RKM said:


> I'd like to have two sets of 45 X 160Ah batt packs for June 2 (my birthday!). Let's hope the testing goes well. What is the lead time once an order is placed?
> 
> Rob


assume 10-15 days to package it... 20-30 days by boat... another 1-2 weeks to repackage and send them all out.

PM me your email so I can accumulate interested parties... I really won't have time to hook my baseboard heater element till after my exam on thursday

My ICE died today (after 99,993 miles without a single problem... not joking). It's likely a death that will end in the scrapyard (engine appears to have seized)

So this looks like about the right time to build.


----------



## ravlegend (Feb 6, 2009)

Thanks for the work tech.

Doesn't Skyenergy stocks their own "brand" BMS and charger for the common voltage packs (24v, 48v etc)? 

Anticipating your next round of testing at 1c.


----------



## yerneni (Mar 12, 2009)

I exchanged email with a skyenergy person and she referred me to another company for BMS and charger. I also contacted Chinabattery and jnd folks and they are claiming to have their own BMS and charger...wondering how good they are and whether it's worth getting them seperately?

Any comments, experience form these companies? I am looking to build a 48V 60/90AH for a motorcycle. 



ravlegend said:


> Thanks for the work tech.
> 
> Doesn't Skyenergy stocks their own "brand" BMS and charger for the common voltage packs (24v, 48v etc)?
> 
> Anticipating your next round of testing at 1c.


----------



## dfarmer (Mar 2, 2009)

China Hi Power has chargers with a BMS built in that charge each cell individually. Here is the prices they quoted me:

4. the price of balancing charger/BMS

We offer customer 12v ,24v,36v ,48V,72v 96V,120V,144V,192V,240V,288V ,2AMP ,8AMP /25AMP / 50AMP fantastic charger with the balancing function which charge and balance each single cell seperately thus can prolong and gurantee the longest life of the battery . We can offer to you the full BMS and charger . 
Our balancing Charger/BMS`s sample price : 
48v 8AMP charger price : Mass order price is USD 90 . Few sample order price is USD 136. 
36v 2AMP charger price : Mass order price is USD 45 . Few sample order price is USD 78. 
60V 8amp charger price: Mass order（over 200sets）price is USD 110 .Few sample order price is USD 160 . 
72v 25AMP charger price : Mass order price is USD 370 . Few sample order price is USD 442.


----------



## Technologic (Jul 20, 2008)

yerneni said:


> I exchanged email with a skyenergy person and she referred me to another company for BMS and charger. I also contacted Chinabattery and jnd folks and they are claiming to have their own BMS and charger...wondering how good they are and whether it's worth getting them seperately?
> 
> Any comments, experience form these companies? I am looking to build a 48V 60/90AH for a motorcycle.


The chargers and BMS that sky energy have are somewhat overpriced.

I'd suggest just going with the setup given in this thread.

Their charger for 96v ended up being more than they originally told me.


----------



## steiner (Dec 8, 2008)

I wanted to let you know that I have experience with HiPower batteries and their chargers. Some of their sales people say that their chargers charge each cell individually. They do not do that. Their chargers are standard chargers meaning that they attach to each end of your battery string like a normal charger. Their BMS is built into the charger and does monitor each cell for over voltage during charging. It dumps excess current to a load resistor like many other BMS units.


----------



## Hondacrzy (Mar 15, 2008)

Hey Tech,
Any more tests to report on? 

Any one know how to tell your wife that now that you have spent $8000 on your converting your car. Now you want to buy $7000 in batteries and a BMS?


----------



## Technologic (Jul 20, 2008)

Hondacrzy said:


> Hey Tech,
> Any more tests to report on?
> 
> Any one know how to tell your wife that now that you have spent $8000 on your converting your car. Now you want to buy $7000 in batteries and a BMS?


Once my parts express box gets here tomorrow or Friday I should have something for you guys.

Since my car broke down I couldn't go to the store to get stuff (damn ICEs)


----------



## Voltswagen (Nov 13, 2008)

Any one know how to tell your wife that now that you have spent $8000 on your converting your car. Now you want to buy $7000 in batteries and a BMS?[/quote]

Thats an easy one. I just told my wife if she lost 20lbs she could qualify to donate her eggs and recoup the $7,000.00

Her first shot missed....hitting a picture frame behind me....second shot hit the back door jamb.


----------



## Guest (Apr 2, 2009)

steiner said:


> Their BMS is built into the charger and does monitor each cell for over voltage during charging.


I can't see the BMS in the charger being able to monitor each cell if the charger only connects to the pack like a normal charger. Two attachment points can't monitor each cell. Got photos of how they manage the single cell monitoring with this setup? 

Pete : )

Sounds like sales pitches to me.


----------



## steiner (Dec 8, 2008)

Gottdi,

The charger of theirs that I used had a 25 pin connector that provided the necessary leads to connect to the 24 cells. This is how they are able to monitor the cells for over voltage. The charger/balancer also contains the appropriate number of LEDs on top to show you which cells are being bypassed.


----------



## Guest (Apr 3, 2009)

Thanks for the clarification on that. I kinda figured that may be how it was done after I sent the question. 

Thanks 
Pete : )


----------



## speculawyer (Feb 10, 2009)

steiner said:


> The charger of theirs that I used had a 25 pin connector that provided the necessary leads to connect to the 24 cells. This is how they are able to monitor the cells for over voltage. The charger/balancer also contains the appropriate number of LEDs on top to show you which cells are being bypassed.


Link? sounds interesting.


----------



## Jordysport (Mar 22, 2009)

Could someone enlighten me on the size of these packs please. and is $6.28 per pack (3.2V 90AH) if so that is ***************************  Cheap. 

Many thanks.

ok found out size: 220mm x 142mm x 67mm

Does anyone know of some cheap International Shippers???  about $400 atm for 22 units.


----------



## ClintK (Apr 27, 2008)

Jordysport said:


> Could someone enlighten me on the size of these packs please. and is $6.28 per pack (3.2V 90AH) if so that is ***************************  Cheap.
> 
> Many thanks.
> 
> ...


3.2V*90Ah*.35= $100.80


----------



## ClintK (Apr 27, 2008)

Technologic said:


> Here's the charger I will probably be going with for $203:
> http://www.bmsbattery.com/index.php...id=187&zenid=6a5968383c286a860b3bfbec251a74e1


That charger is about a quarter of the price of similar chargers I've found elsewhere. Is there a reason for its price? Do other chargers have multiple charging cycles that this one doesn't or is it just a great deal?

EDIT:
I stand corrected, the charger does have separate charge and float stages:


> These chargers will charge any 12Volts-600Volts LiFePO4 batteries, Lithium Ion batteries and lead acid batteries. It is fully automatic and will charge at a rate up to about 200 Amperes until the battery voltage reaches a preset point at which it will switch to a very low current float charge. If the battery voltage drops again the charger will begin charging until the voltage once again reaches the cut off point. In this way it can be left connected to a battery indefinitely to maintain full charge without causing damage. An LED indicates when the battery is fully charged.


----------



## Jordysport (Mar 22, 2009)

ClintK said:


> 3.2V*90Ah*.35= $100.80


that makes no sense as he states $440 for 70 of TK90AHA 

which is $6.29 per unit. :S :S :S


----------



## TheSGC (Nov 15, 2007)

Jordysport said:


> that makes no sense as he states $440 for 70 of TK90AHA
> 
> which is $6.29 per unit. :S :S :S


No where in this thread does anyone list $440 for 70 cells of TK90AHA. There is, however, a mention for a BMS/Charger for $432. 

The TK90AHA is $0.35/Wh in mass group order, or $112.50 USD for a sample cell. (I too got my own quotes, then same Tech got.)


----------



## Jordysport (Mar 22, 2009)

Technologic said:


> In the last 24 hours I received a Revised quotation for shipping on the TK90AHA and have received a price of $440 for 70 pieces
> or $6.20/each


this is what confused me.


----------



## JRP3 (Mar 7, 2008)

Jordysport said:


> this is what confused me.


That's for shipping only, not the batteries.


----------



## JRP3 (Mar 7, 2008)

ClintK said:


> That charger is about a quarter of the price of similar chargers I've found elsewhere. Is there a reason for its price? Do other chargers have multiple charging cycles that this one doesn't or is it just a great deal?
> 
> EDIT:
> I stand corrected, the charger does have separate charge and float stages:


I get an error message when I click the link, and when I click on "chargers" all I see are ads for video games


----------



## ClintK (Apr 27, 2008)

JRP3 said:


> I get an error message when I click the link, and when I click on "chargers" all I see are ads for video games


Odd... yesterday they sold battery chargers. Today, video games?

I'm sure that makes sense to someone.


----------



## Technologic (Jul 20, 2008)

ClintK said:


> Odd... yesterday they sold battery chargers. Today, video games?
> 
> I'm sure that makes sense to someone.


I just noticed this as well. People actually received their chargers as of a few weeks ago on endless sphere 
Shucks hope it's just some hack job or something.


----------



## JRP3 (Mar 7, 2008)

Though the original link doesn't show any products they seem to be back to selling chargers: http://www.bmsbattery.com/index.php?cPath=2&osCsid=57b8ec7d1327eb6c0445b796463085ab
Which one were you thinking of using?


----------



## ClintK (Apr 27, 2008)

JRP3 said:


> Though the original link doesn't show any products they seem to be back to selling chargers: http://www.bmsbattery.com/index.php?cPath=2&osCsid=57b8ec7d1327eb6c0445b796463085ab
> Which one were you thinking of using?


You're right, the chargers are back. Unfortunately with a different selection and higher prices.


----------



## yamez4u (Feb 10, 2009)

Still see chargers myself. http://www.bmsbattery.com/


----------



## ClintK (Apr 27, 2008)

Argh, so I was in the process of purchasing the charger from them... They want my username, password, e-mail address, phone number, street address, and date of birth on an -unsecured- website. Genius!

I may try calling to order, but they're in China. Tech, do you have any alternate charger sellers you were looking at?

EDIT: I was going to get the 1500W charger.


----------



## Technologic (Jul 20, 2008)

ClintK said:


> I may try calling to order, but they're in China. Tech, do you have any alternate charger sellers you were looking at?


not at the moment... I'll look around. China doesn't bother me much.

They did increase the price of the charger I wanted  I'll see what I can come up with.

They still have the 1500watt charger over there... but it's 40 dollars more.


----------



## JRP3 (Mar 7, 2008)

I don't see any specifications for their chargers, other than the wattage. Also, there seems to be a lot of empty space inside this charger, though the pic may be deceiving, and what's that loose plug in there?


----------



## Technologic (Jul 20, 2008)

JRP3 said:


> I don't see any specifications for their chargers, other than the wattage. Also, there seems to be a lot of empty space inside this charger, though the pic may be deceiving, and what's that loose plug in there?


I've seen someone at endless sphere talk about purchasing one with great results (several people have actually) so I was thinking about taking the plunge

that case actually looks empty... possibly taking pictures of products they are were still designing at the time? (or manufacturing?)

Not sure what to think about the change of scenery.


----------



## ClintK (Apr 27, 2008)

ecitypower.com shows the same charger:
http://www.ecitypower.com/index.php?page=70

1500 Watts, 15V-400V


----------



## ClintK (Apr 27, 2008)

I sent them an e-mail earlier today asking about adjusting the voltage / varying charge cycles, just got this back:



> All the chargers are special designed for your special project. They are not adjustable.


They also sent an Excel sheet with the specs of all their products:
Model Description Weight(kg) Dimension(mm) Unit Price
EP-D 1500Watts LiFePO4/Lithium Ion Chargers 6 300x175x98 $244.00


----------



## Technologic (Jul 20, 2008)

I was waiting for a package that contained better battery terminals etc so I can do my testing, but I'm fairly certain someone stole it after it was delivered 

Pretty pissed off about it.

Stealing $10 of battery terminals for $1 of crack on the street?


----------



## david85 (Nov 12, 2007)

Usually when we get a package delivered and no one is home, the package is not left unatended and is instead taken to the nearest post office. An official message with ID info is left behind to let us know when/where I can go get the parcel. Not sure how it works where you are. Have you tried contacting the shipper to find out when it should have been dropped off?


If it really was stolen by a crack head, then maybe he will OD on whatever he manages to find. Small comfort, but still something.


----------



## Technologic (Jul 20, 2008)

david85 said:


> Usually when we get a package delivered and no one is home, the package is not left unatended and is instead taken to the nearest post office. An official message with ID info is left behind to let us know when/where I can go get the parcel. Not sure how it works where you are. Have you tried contacting the shipper to find out when it should have been dropped off?


Duke University isn't a nice area despite heavy campus police (possibly the largest employed university police force per student in the US? I wouldn't be surprised... there's over 200 officers in the day and 500 at night on duty for only 6000 students)
http://www.newsobserver.com/576/story/391097.html



> If it really was stolen by a crack head, then maybe he will OD on whatever he manages to find. Small comfort, but still something.


UPS is the one that left it on my porch... and worse is it was stolen in the mere 1 hour I was gone today... how horrible is that luck?
I need to call UPS and confirm tomorrow... sometimes the tracking data is totally wrong and stuff


----------



## ClintK (Apr 27, 2008)

Tech, since you've been testing these cells can I have your opinion on this...

My controller has a cutoff voltage of 80V.

I'd like to use a 96V pack (90AHr) because it fits my price range, 96V is a standard voltage for chargers, and I don't want to go too high on the voltage as my motor is only a L91-4003. I alternatively could do 32 cells or 34 cells for a little more voltage.

Have you noticed the cells to have much of a voltage sag? If my pack is 70% discharged and I try to accelerate do you think I'll drop below 80V?

Thanks!


----------



## Technologic (Jul 20, 2008)

ClintK said:


> Tech, since you've been testing these cells can I have your opinion on this...
> 
> My controller has a cutoff voltage of 80V.
> 
> ...


If anything they seem to not sag at all... though only further 1C testing will be able to tell for sure.

for about 20-40% of their capacity they seem to hover at 3.2v under load or thereabouts.

I wouldn't plan on anything less than 3.1v average during loads.

Also at 70% the pack could easily be 2.9v or so... so expect that under very heavy load (2-3C) it will sag maybe down to 2.6 or 2.5v...

Just a guess though, I'm still waiting on parts to finish my tests.


----------



## dimitri (May 16, 2008)

ClintK said:


> Tech, since you've been testing these cells can I have your opinion on this...
> 
> My controller has a cutoff voltage of 80V.
> 
> ...


Clint,

you should go with 30 cells. It would give you 3.2 x 30 = 96V nominal and 2.66 x 30 = 80V low voltage cutoff. Perfect numbers for 30 cells pack.

You still need to balance the pack to make sure all cells get to LVC somewhat evenly and try not to get it to LVC at all. LVC should be your last resort protection.

As for charger, you can't just use any off the shelf charger, even if its correct voltage. You need proper charging profile for LiFePo4 cells.

Also, these cells are knock off from Thundersky, so you can pretty much use documents and graphs published by TS to make your decisions.

Hope this helps.


----------



## ClintK (Apr 27, 2008)

Thank you much guys! I'll go with the 96V. The batteries should be ordered this week.

For charging I'm thinking ecitypower's 1500W charger (post #130) depending on their shipping costs. Elite Power quoted me $500 for a 96V charger, but then I get to deal locally.

For balancing I'll probably pick up the Volt Blochers http://www.voltblocher.com/About.html I like the method it uses and the price is reasonable.


----------



## Technologic (Jul 20, 2008)

dimitri said:


> Also, these cells are knock off from Thundersky, so you can pretty much use documents and graphs published by TS to make your decisions.
> 
> Hope this helps.


I'm pretty sure Thundersky is actually a knock off of Sky Energy.

Sky Energy appears to supply all of their batteries per the government's orders.

Note the entire warehouse of yellow batteries.

It also seems fairly intuitive since Sky Energy's prices are so low.


----------



## dimitri (May 16, 2008)

Thundersky is original corporation that developed large prismatic cells and its been in this business for almost 10 years. Sky Energy is government owned company that recently stepped into the lithium market because it has huge growth potential, they took Thundersky blueprints and started making their cells with just a different case color. They do it because they can, who can say no to government in communist country?

Do we, as consumers, benefit from this? Sure we do, we get cheaper batteries because they flood the market. Do I care if this is how business done in China? I care a little, but not enough to boycott their products.

As long as they make decent quality product at competitive prices, that's fine with me. If US companies wanted to be in this market, they could compete by automating the hell out of production process and minimize labor costs, but no, they rather take our tax dollars and make overpriced product for OEM use only.

Sorry, lets not turn this into political thread, there are plenty of those in the Chat forum.

Admins, feel free to delete this post.....


----------



## Technologic (Jul 20, 2008)

dimitri said:


> Thundersky is original corporation that developed large prismatic cells and its been in this business for almost 10 years. Sky Energy is government owned company that recently stepped into the lithium market because it has huge growth potential, they took Thundersky blueprints and started making their cells with just a different case color. They do it because they can, who can say no to government in communist country?
> 
> Do we, as consumers, benefit from this? Sure we do, we get cheaper batteries because they flood the market. Do I care if this is how business done in China? I care a little, but not enough to boycott their products.


I'm pretty sure this is what happened to a point, but now it's clear Thundersky is asking sky energy to make batteries for them to then resell as well.

They don't offer yellow cases, and I was told they are for thundersky only upon some agreement they have.

At any rate... the batteries seem pretty good and meet standard expectations people have from prismatics... the big difference is the pack prices being significantly lower.


----------



## JRP3 (Mar 7, 2008)

Dave Kois from poweredbydc.com says his last Thundersky battery order came in blue cases, at the same prices, and I think he feels they are basically the same company.


----------



## ClintK (Apr 27, 2008)

If Sky Energy gives me a reasonable shipping price I'll be ordering this week.


----------



## Powered By DC (Jan 3, 2009)

Here is what I know, Sky energy is an OEM for TS they produce cells for TS. They have been doing this for some time and as of late they have had some issues with some of the other TS factories that order from them so they decided to market them on their own. They are also partially owned by the millitary as was pointed out earlier. They produce cells to TS specs but also have 2 other cell chemistries that are their own and are different. The specs are very different. They have a TK and ans SE cell. The SE cells are supposed to be better than the TK cells. The SE cells are about 5 cents more per ah . They have sent me some cells to test and I will let you all know how they stack up. If the cells test out well I will be placing a very large order at the end of the month. If anyone wants to add on to my order let me know. We are also testing cells from every other major manufactuer. Which ever cells look the best we will be working to get the best price on.

Dave Kois
Powered By DC, LLC
www.poweredbydc.com
[email protected]
skype dkoisii


----------



## RKM (Jun 9, 2008)

Dave,

I'm interested in a quality cell at a value price. I'll soon be wanting 90 X 160Ah cells (two vehicles). Looking forward to seeing your specs and test results.

Rob


----------



## yamez4u (Feb 10, 2009)

That is about the number I'm look at as well, Two motors one boat. If you go through the trouble of getting a quote let me know what it is.


----------



## Voltswagen (Nov 13, 2008)

Technologic
I just received an email featuring the enclosed ad for LiFePo. Seems like a reasonable price and I like the Free Shipping idea. Also since they are in Michigan it avoids the duty and customs fees and hassels.
Could you check their specs and comment on how they compare to the batteries you are testing?
Thanks - Roy

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200329295027


----------



## JRP3 (Mar 7, 2008)

I received the same email. They are Thundersky batteries, and you aren't avoiding any costs, they are just adding those costs to the price of the battery. You can do better by getting in on the bulk order that Dave Kois is doing from www.poweredbydc.com


----------



## JRP3 (Mar 7, 2008)

An interesting post from Sky Energy on the EVDL:
http://www.evdl.org/archive/index.html#nabble-td23251023
The cells discussed are the newer SE cells, not the TK.


----------



## Technologic (Jul 20, 2008)

JRP3 said:


> An interesting post from Sky Energy on the EVDL:
> http://www.evdl.org/archive/index.html#nabble-td23251023
> The cells discussed are the newer SE cells, not the TK.


Good stuff... looks like my tested chart is better than their's


----------



## Technologic (Jul 20, 2008)

Voltswagen said:


> Technologic
> I just received an email featuring the enclosed ad for LiFePo. Seems like a reasonable price and I like the Free Shipping idea. Also since they are in Michigan it avoids the duty and customs fees and hassels.
> Could you check their specs and comment on how they compare to the batteries you are testing?
> Thanks - Roy
> ...


price seems much higher mate... that's the only thing I can tell from the get go.

Custom fees are only 3% in our country.


----------



## Hondacrzy (Mar 15, 2008)

Tech, did you ever get time to do any tests 1c or higher?


----------



## Technologic (Jul 20, 2008)

Hondacrzy said:


> Tech, did you ever get time to do any tests 1c or higher?


working on it... they lost my package twice and UPS had to replace it twice (for the terminals needed for higher amperage).

I'm working on setting it up very soon now that exams are finished.


----------



## EVComponents (Apr 20, 2009)

Many of you are aware of the recent Thundersky bulk buy that Dave Kois and I organized. This topic here has been discussing the Sky Energy cells. 

Dave (PoweredByDC) has also been testing Sky Energy cells the past few weeks.


Sky Energy contacted us and offered to match the Thundersky price. Prior to this Sky Energy was about $0.05 more expensive per AH. So we are able to do another bulk buy on the same terms as the TS order.

We are ordering 52,000 AHs from Sky Energy this week.

200 X 100 AH cells = 20,000 AH
125 X 160 AH cells = 20,000 AH
200 X 60 AH cells = 12,000 AH

About 50% of this order is already committed to individuals. 

$1.10 per AH plus customs and shipping. We estimate approximately 10% for those fees. 

60 AH Sky Energy = $66 each
100 AH Sky Energy = $110 each
160 AH Sky Energy = $176 each

Those sizes were the most popular (76%) in the Thundersky bulk order. If you want a different size, we can include it. We are ordering these sizes on spec because we know they will be taken before arrival in the port in Seattle.

Contact Dave Kois if you are interested in the Sky Energy LIFEPO4 cells.

Dave Kois 
Powered By DC, LLC 
www.poweredbydc.com 
[email protected] 
253-988-5020 

Thanks,
James Morrison
[email protected]

www.peakoilgarage.com (personal blog)


----------



## ClintK (Apr 27, 2008)

Are those the Sky Energy TK cells or SE cells?


----------



## Technologic (Jul 20, 2008)

ClintK said:


> Are those the Sky Energy TK cells or SE cells?


Apparently they don't make TK cells anymore unless specifically requested... so I hope SE (since that was the SE price I was offered $1.1/AH)


----------



## EVComponents (Apr 20, 2009)

ClintK said:


> Are those the Sky Energy TK cells or SE cells?


I will let Dave answer. He has been dealing with Sky Energy on our order. As I understand it, their website is not accurate and was thrown up quickly. The data is out of date. So what is seen as available is not accurate. We need to confirm which size cells are available in the SE type.

I will send Dave Kois an email and ask him to confirm.


----------



## Technologic (Jul 20, 2008)

EVComponents said:


> I will let Dave answer. He has been dealing with Sky Energy on our order. As I understand it, their website is not accurate and was thrown up quickly. The data is out of date. So what is seen as available is not accurate. We need to confirm which size cells are available in the SE type.
> 
> I will send Dave Kois an email and ask him to confirm.


I was told from them up to 160AH (I think).

Likewise, SE are the current type they make now... apparently sacrificing their TK style unless asked for it.

the SE material is imported to china, but no idea what it is besides that.


----------



## EVComponents (Apr 20, 2009)

Technologic said:


> I was told from them up to 160AH.
> 
> Likewise, SE are the current type they make now... apparently sacrificing their TK style unless asked for it.
> 
> the SE material is imported to china, but no idea what it is besides that.


That is mostly accurate. I just got off of the phone with Dave. He said that as of this month (May) *all of the cells are SE, including the 180 AH size*. The TK cells were discontinued.

Here are the sizes available. (not on their website yet)
40 AH, 60 AH, 90 AH, 100 AH, 120 AH, 160 AH and 180 AH.

We were told they are willing to also introduce the SE cells in 200 AH and 260 AH sizes if there is enough demand from customers in the next few months. They can make the 120 AH SE cell on request, but it is not in regular production yet.

As for this order with Sky Energy, we are ordering the SE cells in these quantities and sizes. This will be a small order of 52,000 AH to see how it goes. 
If all goes well we may try a larger order.

125 units X 160 AH 
200 units X 100 AH
200 units X 60 AH

If you would like a different size cell like the 40 AH (which was also popular in the Thundersky bulk order) let us know ASAP and we can include it.


----------



## david85 (Nov 12, 2007)

Are you saying that thundersky will be completely dead in the near future?


----------



## EVComponents (Apr 20, 2009)

david85 said:


> Are you saying that thundersky will be completely dead in the near future?


No. Not at all. Thundersky is a seperate company from Sky Energy. It appears that they are competing against each other now in a very serious manner.

In fact, it appears that there are numerous companies that operate under the Thundersky brand.

Sky Energy is trying to differentiate themselves.

I am not the expert on this situation. Dave Kois has been dealing with these different companies and understands more about what is going on. Thundersky is still very much around as a company and brand. They are delivering orders.


----------



## Powered By DC (Jan 3, 2009)

No, Sky Energy Is no longer going to make the TK cells they will only be selling the SE cells 

TS will still be around 

Dave Kois
Powered By DC, LLC
EV Components, LLC
[email protected]
[email protected]


----------



## Guest (May 3, 2009)

I'm interested in these new SE cells myself. But it is a bit hard to glean the information.

One thing I did notice that is a little bit of concern is the charging temperature and to a lesser degree, the charge level.

The temperature on the Blue Sky SE cells seems to be 0-55C. The Thunderskys can withstand charging temperatures down to -25C and up to 75C. The -25C is the temp of interest. 

Basically, most Lithium cells react quite badly to charging below freezing. It normally causes lithium metal plating on the cathode, a very problematical thing. The internal flow of the batteries is based on cations of course (positive ions) and the presence of Lithium metal per se allows these ions to recombine immediately with any lithium present to basically absorb the ions. Hugely diminished battery capacity and some risk of instability. 

This is almost identical to what happens to the cell from overcharging. 

0C is of course 32F - the freezing point. We don't get down to -25C at all here in MIssouri. But we quite commonly do get down below freezing. It would appear from the spec that if charge in that event we could damage the cells.

The lesser element of concern is charge rate. It would appear they want it held below 1C for the Blue Sky's while TS allows up to 3C charge. There is some diminished cycle life at 3C purportedly. But I was wanting to experiment with it. 

The problem has always been where to GET 3C. But I think I have it worked out. With a second battery bank, slowly charged by solar or a regular charger, and a few cells more than my car pack, I should be able to connect with some heavy 2/0 and charge in about 20 minutes. I was going to try this first with a few cells and see if it worked. But it doesn't appear the BlueSky supports anything over 1C.

Beyond that, I want to try some anyway. The 100AH SE seem to be about the same size and weight as the TS 90AH.

Jack Rickard
1957 Porsche eSpeedster
http://web.me.com/mjrickard


----------



## JRP3 (Mar 7, 2008)

jrickard said:


> Beyond that, I want to try some anyway. The 100AH SE seem to be about the same size and weight as the TS 90AH.


The specs I've seen from TS show the same size and weight for both their 90 and 100AH cells. 220mm x 145mm x 68mm and 3.2kg.


----------



## Powered By DC (Jan 3, 2009)

Jack - I believe Sky rates their cells from 0-55 degrees C for exactly the reasons you listed above. Charging below freezing will damage the cells regardless if they are TS or SKy. The Sky cells can be charged below 0 degrees and I have seen the comparison curves for both TS and Sky at -20C and The Sky cells perform much better than the TS cells in both charge and discharge. The Sky cells discharge to 85% of their rated capacity while the TS cells only discharge to 60% of their rated capacity at -20C

As for the rate of charge the sky cells are rated to 3C not 1C as you had mentioned. If you would like I can send you the specs. I tried to upload it on this message but the file is too big

Dave Kois
Powered By DC, LLC
EV Components, LLC
[email protected]
253-988-5020


----------



## JRP3 (Mar 7, 2008)

Here is a link to the Sky Energy SE100AH cell data, though they don't give dimensions:
http://skyenergy.en.alibaba.com/product/223091258-200652425/SE100Ah_Lithium_battery.html


----------



## Guest (May 3, 2009)

Yes, I'd love to see a spec sheet. I was going from the very limited specs they had on their web site. 

The THundersky spec sheet clearly indicates -25C as the lower limit. If they have plating below 0C that would be alarming as I've charged down to about 15F on several occasions. They seemed to charge normally.

We've learned some from the Thunderskys. I've got a lab in the back of the garage with some pretty good test equipment and I've tortured a few of these cells pretty good. The biggest thing I've learned is not to charge them fully, or for that matter discharge them fully. 

The balancing problems seem to come in in the range of about 3.8 to 4.25 volts. And this is very high up on the steep side of the charge curve anyway. You are not actually getting that much energy in, and individual cells in a series pack start to wander pretty badly. A few minutes inattention and we'll have one jump up to 4.5 v. 

What this has led me to is that a programmable charger is actually more of a requirement than a Battery Management System or shunt balancers. I've actually destroyed cells with some of the balancers out there we've tested. I've developed one myself that works pretty well, but I've decided they are just dangerous. They give off a good bit of heat, and if a semiconductor of whatever ilk you choose goes thermal, you lose a cell. 

So we are eschewing BMS systems per se, and shunt balancers specifically. But we do use a kind of expensive BRUSA charger. This lets us set some fairly exotic multiple charge stages. Best, the BRUSA is pretty good at differentiating the actual battery pack voltage from its own charge voltage.

Basically, we charge to 3.6-3.7 volts per cell. And FORFEIT all charging above that. It has made the balancing problems pretty much disappear and we don't have to worry at that level about individual cells going off into 5 volt land. I don't really think it causes us to lose a mile or two in range.

I am working on a kind of simplified display system using a 20 segment bar graph for each 4 cell pack. As I have 16 packs, this winds up being about an 8 inch by 2 inch display that looks like a graphic equalizer. The advantage is that it is easy to glance at and see the voltage of all 4-cell packs and better, to see their voltage under load while accelerating. The 20 segments display 10-13.85v.

And that's pretty much it. I no longer buy the active balancing theory and the BMS systems we've looked at and indeed purchased at some expense have not been sufficiently useful to go through the wiring to put on a car. We're opting for a simple display and a somewhat pricey charger (a little over $3000). But I think the charger is very key to operation.

In any event, I'd love to see the data sheet if they have provided you one and would be happy to be included in the bulk buy if you still have some available.

Jack Rickard
[email protected]

http://web.me.com/mjrickard


----------



## EVComponents (Apr 20, 2009)

jrickard said:


> Basically, we charge to 3.6-3.7 volts per cell. And FORFEIT all charging above that. It has made the balancing problems pretty much disappear and we don't have to worry at that level about individual cells going off into 5 volt land. I don't really think it causes us to lose a mile or two in range.


I think in one of these TS or SE topics Dave Kois mentioned that in his experience it is pointless to charge above 3.6 volts. You don't get that much more energy and as soon as you put a load on the cells they drop to 3.2 volts and stay there. Dave might clarify his comments if he sees this.



jrickard said:


> In any event, I'd love to see the data sheet if they have provided you one and would be happy to be included in the bulk buy if you still have some available.


We are doing the Sky Energy order this week so let Dave know specifically what you want and we can include it.

Thanks,
James Morrison
[email protected]


----------



## david85 (Nov 12, 2007)

I agree with the 3.6V top end limit. My batteries are not thundersky or sky energy, but they are the same basic chemistry. I would consider 2.5-3.5 to be your ideal operating range. What I found interesting is the discharge curve was so flat in my case that it was almost pointless to even go below 3V unless you were drawing high amps or wanted every last ounce of energy. After 3V it tends to drop off quickly.

SE cells seem to have more of sloping discharge curve though, so you might simply have to go to deeper cell voltage to get your money's worth out of each cycle.

According to the info I got from my supplier, the cells can in theory fail at 10.5V each, so 4.25V is probably still not going to result in an instant dead cell, but I'm willing to bet that it will affect cycle life. I think the 2V-4.25V range is more for personal safety than ideal operating range of the battery. I would not advise operating them that wide.

You are also right about cells going further out of balance at the top and bottom ends of each cycle. This has been known going back to when LiPo cells became popular in RC sport competition. If you keep the C rates and discharge cycles close together enough, they will self balance. Its not officially recommended, but its been observed going all the way back to LiCO2 spiral cells. LiFePO4 is only more forgiving.

Monitoring of individual cells would still be a good idea in case on cell in the lot completely fails. But considering each cell is made up of several soft packs in parallel, even that is an unlikely event.


----------



## Technologic (Jul 20, 2008)

david85 said:


> I agree with the 3.6V top end limit. My batteries are not thundersky or sky energy, but they are the same basic chemistry. I would consider 2.5-3.5 to be your ideal operating range. What I found interesting is the discharge curve was so flat in my case that it was almost pointless to even go below 3V unless you were drawing high amps or wanted every last ounce of energy. After 3V it tends to drop off quickly.
> 
> SE cells seem to have more of sloping discharge curve though, so you might simply have to go to deeper cell voltage to get your money's worth out of each cycle.


Has their been any independent testing? because if it's a worse curve there's 0 reason to buy them over the cheaper TKs (and they do still make the TK).


----------



## david85 (Nov 12, 2007)

Technologic said:


> Has their been any independent testing? because if it's a worse curve there's 0 reason to buy them over the cheaper TKs (and they do still make the TK).


Not aware of independant testing other than what you did. BUT......

I was recently sent info from some one at sky energy offering to sell batteries (some one contacted me while my trade manager was online). Their discharge curve profile closely matched the results of your testing. The official info seems to be accurate from all the chinese suppliers so far.

In the case of my testing, there too the discharge profile closely matched that of the manufacturer's chart.

The SE cells are said to have more energy density (about a 15% improvement) so even with a worse discharge curve it might not matter that much. However, if that extra rating comes from a 2V-4.25V operating range, then it might be a case of having to read between the lines.

Based on the cycle life projections, and discharge curve I'm still not convinced that they are worth getting too exited about. If the price is right then maybe, but I suspect they are only a small evolutionary step forward compared to older LFP batteries IMO.


----------



## Technologic (Jul 20, 2008)

david85 said:


> Not aware of independant testing other than what you did. BUT......
> 
> I was recently sent info from some one at sky energy offering to sell batteries (some one contacted me while my trade manager was online). Their discharge curve profile closely matched the results of your testing. The official info seems to be accurate from all the chinese suppliers so far.
> 
> ...



Well they have offered me the same price on the SE as they did for the TK... so I'd say the price was "good" in that regard... if the curve is the same, that's also very good IMO.


----------



## gdirwin (Apr 7, 2009)

Can we go back to the low temperature operation of the SE vs TK cells? It gets to -40 where I live, and I plan to drive an EV year round...

TK specs say -25C for charging and discharging.

SE specs say 0C for charging, and -25C for discharging.

Any reason for the difference? I thought TK cells did not like charging in cold weather, so heating blankets, insulated boxes etc... are required, and it is best to immediately plug in after arriving home. Is -25C charging correct?

All help appreciated!


----------



## david85 (Nov 12, 2007)

Technologic said:


> Well they have offered me the same price on the SE as they did for the TK... so I'd say the price was "good" in that regard... if the curve is the same, that's also very good IMO.


There is a difference between the SE/TS batteries and the cells I tested. Mine seem to hold voltage higher for longer and the discharge curve is nearly flat all the way to 80% DOD. Yours seem to have a slop that falls off at an increasing rate almost from full charge. I don't know if you would even notice the difference from driving two cars with different battery types.

As I mentioned earlier on different threads, I wasn't able to find any recent stories of thundersky batteries that didn't perform well. Frankly, I wasn't able to find any bad info about any of these large chinese prismatic LiFePO4 batteries thundersky or others like hipower.

From now on, I predict it will be a battle of price instead of performance. Any defect that is discovered could mean disaster for any of the companies. Chinese companies are as cut throat as it gets and they will not shy away from bad mouthing competitors. Their fight is our gain.


----------



## david85 (Nov 12, 2007)

gdirwin said:


> Can we go back to the low temperature operation of the SE vs TK cells? It gets to -40 where I live, and I plan to drive an EV year round...
> 
> TK specs say -25C for charging and discharging.
> 
> ...


Welcome to the forum.

I don't think any lithium batteries mentioned so far are really going to like being recharged below 0 degrees C.

Specs I got for comparison between TS and SE cells for discharge below zero are as followes:

0C TS60% capacity, SE85% capacity

So cold weather performance has improved, but I don't have any info yet that tells me its recommended to recharge them below zero.


----------



## JRP3 (Mar 7, 2008)

jrickard said:


> So we are eschewing BMS systems per se, and shunt balancers specifically. But we do use a kind of expensive BRUSA charger. This lets us set some fairly exotic multiple charge stages. Best, the BRUSA is pretty good at differentiating the actual battery pack voltage from its own charge voltage.
> 
> Basically, we charge to 3.6-3.7 volts per cell. And FORFEIT all charging above that. It has made the balancing problems pretty much disappear and we don't have to worry at that level about individual cells going off into 5 volt land. I don't really think it causes us to lose a mile or two in range.


Do you somehow pre balance the cells individually before the first pack charge? I don't see how any bulk charger that doesn't monitor individual cells can avoid over or undercharging individual cells unless they start out balanced to begin with. I was thinking that maybe wiring all cells in parallel and letting them sit there for a while, or finding a 3.7 volt charger and charging each cell individually before putting the pack together might be a good idea to get the cells closer to each other.


----------



## david85 (Nov 12, 2007)

All cells are supposed to be charged to the same SOC from factory. This is for the example you just gave, but its also to comply with international shipping regulations and to maximise storage life time.

Checking the individual cells before the first change of the assembled battery is a good idea just in case though. A single cell charger might be a good thing to have around in the event that one cell is too far out.


----------



## JRP3 (Mar 7, 2008)

Have you seen any single cell LiFePO4 chargers, other than a basic power supply?


----------



## david85 (Nov 12, 2007)

JRP3 said:


> Have you seen any single cell LiFePO4 chargers, other than a basic power supply?


Well no. But I see no reason why you can't get them since all the hipower chargers seem to be modular. I guess I could ask if they are available.


----------



## Guest (May 4, 2009)

I don't actually view a more progressive charge/discharge curve as a "worse" curve. It's a different curve, as would be expected from a different chemistry.

I have grown accustomed to the vey flat curve of the LFP cells. It is not precisely true that you cannot tell anything about SOC from voltage with these cells. I have tested it extensively and it simply isn't true. Between a rather huge load bank I've made, and a simple charger, I can "tune" a battery to whatever SOC I want by voltage. But you have to be able to accurately read to a hundredth of a volt. I've got a pretty good bench multimeter that does this quite well.

But you do have to be able to measure very small changes in voltage accurately, and wiring and connections can cause anomalies. A more sloping curve would make this easier for me (I think).

Jack Rickard
http://web.me.com/mjrickard


----------



## ev_geek (Mar 25, 2009)

*Re: Sky Energy TK90AHA test 0.35/wh LiFePO - Is there a conclusion?*

I have been watching and waiting on this tread...any final conclusions on these battery packs? The SkyEnergy guys seem to be pretty aggressive in pushing the product...Before plunking down a couple of grand, I was hoping to hear some good news...!

The website only says they are Lithium Ion batteries...I assume they are Li Iron phosphate batteries?


----------



## EVComponents (Apr 20, 2009)

*Re: Sky Energy TK90AHA test 0.35/wh LiFePO - Is there a conclusion?*



ev_geek said:


> I have been watching and waiting on this tread...any final conclusions on these battery packs? The SkyEnergy guys seem to be pretty aggressive in pushing the product...Before plunking down a couple of grand, I was hoping to hear some good news...!
> 
> The website only says they are Lithium Ion batteries...I assume they are Li Iron phosphate batteries?


Yes. Lithium Iron Phosphate. Since I am one of the guys selling them, of course I believe they are good. I just purchased 105 of the Sky Energy SE 100 Ah cells for a conversion we are working on.

So I believe in the quality and performance to invest in putting them in a 2009 RAV4 EV conversion.

http://www.flickr.com/photos/[email protected]/sets/72157617145858680/

James Morrison
www.evcomponents.com


----------



## Guest (May 15, 2009)

They are lithium ion iron phosphate. I know of no one here in the states that has actually tested them in a car (David Kois??). 

Here's what I've been able to find out. THey appear to have modified the nano structure of the carbon anode of the cell. It now features a 15 micrometer particle that is itself made up of 200-300 particles of nanometer size. This somewhat substantially increases the surface area of the anode material while helping it remain stable.

It sounds pretty good to me. The story goes that this leads to less degradation over cycle life, which is my hot button on these batteries.

Jack Rickard
http://www.evtv.me


----------



## EVComponents (Apr 20, 2009)

jrickard said:


> They are lithium ion iron phosphate. I know of no one here in the states that has actually tested them in a car (David Kois??).


Dave Kois has done several RAV4 conversions with these SE cells.

www.poweredbydc.com

And based on my order list, there are about 40 people who are about to do it in July.

Thunder Sky and Sky Energy cells are close enough that Thunder Sky doesn't even ask you before they will subcontract orders out to Sky Energy.
If you order the 100 Ah cells from Thunder Sky, there is a high probability that the Sky Energy SE 100 Ah cells will be what is actually delivered to you.

So they obviously feel that the cells are interchangable for their orders.


----------



## Guest (May 15, 2009)

I've had several orders of THunderskys in the past few months. None have been SE batteries.

I was unaware that they had actually used Blue Sky SE batteries in a rolling RAV4. I have myself entered an order for 100 100Ah SE cells through them.

Jack Rickard
http://www.ev-tv.me


----------



## EVComponents (Apr 20, 2009)

jrickard said:


> I've had several orders of THunderskys in the past few months. None have been SE batteries.


Was the size of the cell 100 Ah in those other orders? I think that SE 100 Ah cell is a specialty of Sky Energy and most Thundersky factories did not manufacture that size. There are several different Thundersky factories that each handle their own orders and sales. It might depend on which one you were dealing with. 

I just took delivery of 105 x 100 Ah of the SE batteries. That order was placed with the Thundersky back in March. They did not even ask us, they just sent the SE batteries instead. I am actually glad that they did. The more I have learned about SE the more impressed I have become.


----------



## ev_geek (Mar 25, 2009)

*Re: Sky Energy TK90AHA test 0.35/wh LiFePO - Is there a conclusion?*

Thanks. What is the difference between their SE and TK product lines? Also, what is a good reasonably priced BMS and Charger we can use? My application is a 3 wheeler weighing about 120kgs and expecting to take-on another 130-150kgs. Debating whether I should go for a 36v assembly or 48v and plan on experimenting. I assume it is ok to build a 36v assembly and use a step-up transformer to a 48v motor/controller?




EVComponents said:


> Yes. Lithium Iron Phosphate. Since I am one of the guys selling them, of course I believe they are good. I just purchased 105 of the Sky Energy SE 100 Ah cells for a conversion we are working on.
> 
> So I believe in the quality and performance to invest in putting them in a 2009 RAV4 EV conversion.
> 
> ...


----------



## JRP3 (Mar 7, 2008)

*Re: Sky Energy TK90AHA test 0.35/wh LiFePO - Is there a conclusion?*



ev_geek said:


> Thanks. What is the difference between their SE and TK product lines? Also, what is a good reasonably priced BMS and Charger we can use? My application is a 3 wheeler weighing about 120kgs and expecting to take-on another 130-150kgs. Debating whether I should go for a 36v assembly or 48v and plan on experimenting. I assume it is ok to build a 36v assembly and use a step-up transformer to a 48v motor/controller?


Why add the extra efficiency losses and complexity of a step up transformer, when you can just use four extra batteries, which also gives you more capacity?
I don't know if they still make the TK line but I think it's the same as the older TS chemistry.


----------



## EVComponents (Apr 20, 2009)

*Re: Sky Energy TK90AHA test 0.35/wh LiFePO - Is there a conclusion?*



JRP3 said:


> I don't know if they still make the TK line but I think it's the same as the older TS chemistry.


That is correct. As I understand it, Sky Energy used to make the TK cell for Thunder Sky to fill contract orders. They discontinued that on May 1st. Now they supposedly only make the SE cell. Although, you never know with these companies in China.


----------



## EVComponents (Apr 20, 2009)

*Re: Sky Energy TK90AHA test 0.35/wh LiFePO - Is there a conclusion?*



ev_geek said:


> Thanks. What is the difference between their SE and TK product lines? Also, what is a good reasonably priced BMS and Charger we can use? My application is a 3 wheeler weighing about 120kgs and expecting to take-on another 130-150kgs. Debating whether I should go for a 36v assembly or 48v and plan on experimenting. I assume it is ok to build a 36v assembly and use a step-up transformer to a 48v motor/controller?


TK = cells made to Thunder Sky specs to fill contract orders
SE = their own slightly different cell chemistry that has slightly better discharge specs. 4C vs 3C (SE vs TK) and pulse 12C vs 10C.

Please contact [email protected] about your questions with the BMS and charger.

Thanks,
James 
www.evcomponents.com


----------



## ravlegend (Feb 6, 2009)

Is it a misprint on their SE 180ah packs being more energy dense?

Wonder why this didn't get translated in the lower packs series liked the SE 40ah.


----------



## ev_geek (Mar 25, 2009)

*Re: Sky Energy TK90AHA test 0.35/wh LiFePO - Is there a conclusion?*

Yeah, I understand the efficiency losses...but this is only to prototype. We currently have 48V motor/controller/inverter setup. 



JRP3 said:


> Why add the extra efficiency losses and complexity of a step up transformer, when you can just use four extra batteries, which also gives you more capacity?
> I don't know if they still make the TK line but I think it's the same as the older TS chemistry.


----------



## Guest (May 16, 2009)

So James. Is it true that you HAVE a rolling RAV-4 using the Sky Energy batteries or that you are working on one?

Jack Rickard


----------



## Powered By DC (Jan 3, 2009)

Jack- All of the rolling Rav4's have been TS. The current 2009 Rav4 will have the 100ah SE cells in it.

Dave Kois
Powered By DC, LLC
EV Components, LLC
http://evcomponents.com
253-988-5020
Skype dkoisii


----------



## david85 (Nov 12, 2007)

All the rolling rav4s? How many did you build so far?

Sounds like you are well on your way


----------



## EVComponents (Apr 20, 2009)

david85 said:


> All the rolling rav4s? How many did you build so far?
> 
> Sounds like you are well on your way


It is four used RAV4s. The one we are working on right now is a 2009 RAV4 4WD with all of the bells and whistles.

Here is a picture set with the new one (before conversion started). Also in the set are some pictures of the 1996 RAV4 that was converted and has already been sold a few weeks ago.

http://www.flickr.com/photos/[email protected]/sets/72157617145858680/


----------



## JRP3 (Mar 7, 2008)

Do you use the stock auto transmission? Any pics of the EV components? I already know what a RAV4 looks like, I want to see electronics!


----------



## EVComponents (Apr 20, 2009)

JRP3 said:


> Do you use the stock auto transmission? Any pics of the EV components? I already know what a RAV4 looks like, I want to see electronics!


Right now they are only decoding the computer. The engine has not even been removed yet.
We are documenting as we go so that we have a cool slide show and videos after it is done.
As for the parts, Dave Kois will have to chime in for the full list.
The batteries are going to be Sky Energy SE 100 Ah cells.


----------



## weber (Apr 22, 2009)

Wow. Talk about thread drift! But I guess the original topic is of very little interest now that we know the TK cells from Sky Energy are the same as TS cells from Thunder Sky. What we want to see are tests of the SE cells from Sky Energy. But good on you Technologic, for the time you've put in.

You don't need expensive computerised setups to test these cells. All you need is a friend, a stop-watch and pen and paper. Nichrome is too high a resistance for making several hundred amp dummy loads at 3 volts. Ordinary copper wire is all you need, in a water bath. And of course it helps to be using the smallest cell in the range so 6C is _only_ 240 amps. 

You can see how coulomb and I tested a Thunder Sky cell, here:
http://www.aeva.asn.au/forums/forum_posts.asp?TID=980&PN=5

And please note that our final setup uses twin 13 mm^2 wires (2 x 6 AWG). That's 8 times the cross-section of a single 12 AWG. And it measures the cell voltage _at_ the cell terminals. And please note that we thermally insulate the cell to simulate it being in a pack surrounded by many others, and follow its case temperature during, and for about 20 minutes after, discharge.


----------



## Guest (May 22, 2009)

I don't find that particularly useful. To map the voltage curve accurately, you need to maintain a constant current load. 

I have an electronic load device, but I like the Mountain Radio system because it does the graphing of voltage while tracking total amp hours recorded, and it does it at a constant current load on the battery as well.

I don't really understand what you've "determined" using this setup. 

Jack Rickard
http://evtv.me


----------



## weber (Apr 22, 2009)

jrickard said:


> I don't find that particularly useful. To map the voltage curve accurately, you need to maintain a constant current load.


We are not particularly interested in the voltage versus SoC relationship, except to know that it is way to flat (and way too dependent on temperature when under load) for voltage to tell you anything useful about SoC.

And who ever said anything about "accuracy".  The point is, it's good enough. And probably well within the variation between cells. And it's way better than an automated test setup being used by someone who doesn't understand about voltage drops in cables.



> I don't really understand what you've "determined" using this setup.


We've determined roughly what temperature rises will occur when the cell is subjected to various heavy discharges for various lengths of time. e.g. 3C until fully discharged and 6C for one minute. And we've determined roughly what temperature is needed to be able to pull 6C without going below 2.5 V.


----------



## Guest (Jun 1, 2009)

Then you only have about seventy things confused. The biggest one is that there is no NEED to avoid going below 2.5v during discharge. You have violently misread the manufacturers data.

You do not want to DISCHARGE the batteries to the point where the STATIC voltage - that is the voltage of the cell at rest, is below 2.5v. They will routinely sag in voltage under load and going below 2.5v is not a problem at all. But when you cease loading, the battery should rather quickly recover to a voltage that is ABOVE 2.5v.

That you cannot determine state of charge from voltage is comical. The curve IS relatively flat, if you are accustomed to monitoring lead acid cells. But this is a GOOD thing. It makes it very easy to determine SOC with quite a bit of accuracy. But you have to be able to monitor relatively small changes in voltage accurately. Buy a decent multimeter and you're pretty much there. 

It is true that you can't measure it very well with a piece of wire and a five gallon bucket.

I have no concept of what your grousing about cable drops. They vary with current, and cable size and length. What's not to understand? I have a six year old grandson who understands it well enough.


----------



## JRP3 (Mar 7, 2008)

jrickard said:


> You do not want to DISCHARGE the batteries to the point where the STATIC voltage - that is the voltage of the cell at rest, is below 2.5v. They will routinely sag in voltage under load and going below 2.5v is not a problem at all. But when you cease loading, the battery should rather quickly recover to a voltage that is ABOVE 2.5v.


Have you tested how low you can momentarily go before the cell won't recover to above 2.5 or so?


----------



## david85 (Nov 12, 2007)

Actually I THINK the maximum C rating should not draw the cell below the low voltage cut off. This would naturally also mean that the closer to full charge the battery is, the more of that C rating you have access to before the voltage will draw down below the 2.3-2.5 cut off zone.

I performed what I believe was a 3C test on a battery that was rated at 5C and voltage dropped to about 2.62V per cell while under load with the battery starting out on a full charge. After the test, the voltage popped back up to about 3.3V per cell.

This is only my limited experience, and the test was on a prismatic LiFePO4 battery made by sieden instead of SE, so its not a perfect comparison, but from what I observed the battery should be able to deliver the rated peak current without dropping below the low voltage cut off by any significant amount.


----------



## weber (Apr 22, 2009)

Dear jrickard,

Lighten up a bit would ya. 

My reference to a possible failure to understand voltage drop in cables was not aimed at you. I don't know anything about your cell testing work. Have you posted any?

This was just my guess as to the possible source of some problems in results posted earlier in this thread or in threads that lead to this thread. 12 gauge wire was mentioned. But don't get me wrong there either. Anyone who uses their own time and resources to do tests and post the results for the benefit of others deserves praise.

When I said voltage vs SoC was "too flat", I hope you understood I meant "too nearly horizontal", not "too linear". Yes, linear is good. Yes, you _can_ determine LiFePO4 SoC from a rested cell at a known internal temperature. But that's not terribly useful in a vehicle being driven. There no way to know the average internal temperature of the cells at any instant (all you can measure is case or terminal temperature and there is a big thermal time constant) and there's no way to rest them for long enough. Integrating amp-hours with peukert compensation is more useful there.

Yes, taking a cell below 2.5 V (e.g. down to say 2.0 V) briefly under heavy load is nowhere near as bad as taking the rested voltage down there. But the idea that it does no damage at all is debatable. In any case, the BMS we plan to use does not allow the low voltage alarm point to be a function of current hence our desire to know more about the max discharge current vs temperature relationship at 2.5 V.

Now, my friend ... What are those other 68 things I am confused about.


----------



## weber (Apr 22, 2009)

JRP3 said:


> Have you tested how low you can momentarily go before the cell won't recover to above 2.5 or so?


Not tested, but I expect you could go to zero volts, a dead short, pulling maybe 25C from a Thunder Sky depending on temperature, provided it didn't last for more than about 1 second, and it would still bounce back above 2.5 V. Don't try this at home kiddies. Hot burny. 

The question is more, "How much capacity do you permanently lose, and how much does internal resistance permanently increase, every time you do this, or any other momentary excursion below 2.5 V?"

There's nothing magic about 2.5 V either. Even when you stay _above_ 2.5 V, the lower you take the _rested_ voltage, the more capacity you lose per cycle. The same goes for high voltages on charge. It's all tradeoffs. They only have a limited calendar life anyway. For lead-acid the economic optimum was typically around 50% depth of discharge. At least with LiFePO4 it seems likely to be more like 80% DoD.

You can think of a cell in transmission-line terms. Some parts are electrically closer to the terminals than other parts. You can model it as a number of sub-cells in a ladder with resistances between. When you momentarily pull the terminals down to a very low voltage, the sub-cells electrically far from the terminals are still at the rested voltage while those close to the terminals may be fully discharged and undergoing destructive secondary reactions. Soon after you remove the load, the sub-cells near the terminals will be quickly recharged by those far from the terminals, but may have suffered permanent loss of capacity.


----------



## Guest (Jun 2, 2009)

I've done quite a bit of testing of these batteries, and have about 5000 miles on the car using the THunderskys. I tested several types of batteries on GEMS before settling on Thunderskys for the car.

I do have a test rig that can do up to about 100 amps on a single cell, and about 45 amps on a 4 cell batt. It will maintain constant current and graph the voltage, or cycle the battery on and off in a kind of driving simulation.

The batteries do sag under load and it is rather variable. You can see this best not at the cell level, but across the pack simply because the voltage swings are larger and easier to measure. But they also vary from the fully charged condition and increase as you approach the lower end.

The temperature actually doesn't matter. Yes, I'm familiar with what it does, but in the end, you'll come to the same conclusion. Track it and compare it all you want, in the end the curve is the curve.

In practice, you don't have to predict the static voltage from the sag voltage. It's the sag voltage that is a moving target. You can easily see the static at the stop light. I don't wait all day to see what it EVENTUALLY recovers to. If you remove the load at the stop sign, and give it a couple of seconds, that's static enough. If you are below 3.0 volts actually, you don't have very long until it is 2.5 volts. You're already on the losing side of the curve - basically once the 3 disappears, it is time to be pretty close to the house. Their just aren't many amp hours between 2.99 and 2.5.

Damage accrual? Well you've got a couple of things going on here. The life cycles are different at 70% and 80% discharge, so of course the less you discharge them, the better. Under that philosophy, which is more or less inarguable, pick any number you like.

My point was do not be alarmed at 2.0 volts per cell when accelerating. But the 2.5v, while also not a religion, is pretty important at rest. Below that, we are advised that copper shunting can begin to form, and some lithium plating that will decrease the life of the battery. I think, while this is similar, it is also somewhat DIFFERENT from the normal life cycle curve from DOD. At 2.5v and below, the effect changes from gradual wear to more of a damage function.

And I was immediately confused when starting out about WHICH 2.5 volts we were talking about. The factory, and the distributor, both assured me separately, if not quite in the Queen's English, that it was the static voltage they referred to. The sag voltage of course has a lot of variables, current level, duration, age of cells, and current DOD of cells. So a measurement of cell sag voltage to static voltage is of limited utility.

The classic test is to draw a specific and constant amount of current from the cells and observe the cummulative amp hours provided during the test, and the changes in voltage across time. But I will routinely terminate the test at 2.0 volts expecting a recovery to ABOVE 2.5 in essentially every case. 

So basically, among the 68 items, I'm seeing a LOT of focus on temperature, and I've personally not found it very useful. I guess it possibly would be in extremis, but 20-35C it just isn't very.

But I am developing a strong preference for Chinese vendors. I've tested maybe 20 TS 90Ah and 160ah batteries in 4 cell or single cell groups. I haven't found a 90Ah cell or battery putting out less than 94 Ah, and most are up around 100 Ah. I pulled 104Ah from one battery last week.

I've also developed some maturing views on BMS systems. First I couldn't find much in the way of BMS. Then I tried to do my own. Then I went back to shopping. Soon I decided they weren't very important.

More recently I'm coming to view them as actually dangerous. These batteries provide a LOT of power. And almost anything you do to it in a car, as opposed to on the bench, is a bit of a problem. You either have lots of light weight wires running everywhere (even at the battery level, much less this nonsense about monitoring individual cells). Shunt regulators are probably an outright fire threat much more dangerous than having a cell out of balance. And the computer systems are just laughable. 

FIrst, you don't need all that information while driving. Second, there's nothing you can do with it while driving if you had it. And worse, it's not something you can explain easily to your daughter if she wants to drive the car.

But finally, they don't work. None of them. They just don't. I worked for DOD contractors for a dozen years, and the guys who do EMI shielding live in a world of their own, because they are all driven squirrely by the problem within just a few years. I actually laughed out loud when I saw the THundersky BMS. It was a touch screen, a computer, and about 80 lightweight wires to wire to each cell.

Gentlemen, in the rear of your car is a 50-150kW AM radio station, whether you are tuned in or not, sporting 80 light wires of varying lengths AROUND it is just comical. If you don't blow the computer entirely out of the water, the information it displays will be utter nonsense. Works pretty good on the bench, as long as there are no electric motors in the vicinity.

We use an EVISION with a very simple balance circuit that splits the pack in half and measures one side against the other. It displays a very simple LED bargraph. When it is centered, your pack and ALL of its cells will be balanced closely enough. It will deflect several bars over very minute variations in voltage across the two pack halves, indicating an imbalance. It takes a little experimentation to determine just what that is for any given pack voltage. But you get the idea pretty quickly.

If it isn't IN balance then it must be out of balance. We do have some terminal strips and wires bringing all the 4-cell batt voltages up for easy access with a voltmeter. If there IS an imbalance, we go measure all the batt voltages, which takes about 180 seconds. 

IF a battery is out of line with the others, say more than a .3 or .4 volts, we pull the battery and take it to the bench. 

And there we determine if any cells are damaged, out of balance, etc. Often we can bleed some or charge some and get it pretty close. Then discharge the battery pretty low. Then charge it up to the full 4.25 per cell. Then discharge it again. If it seems to be staying inline, we'll consider putting it back in a car.

But that does bring up another subject. Batteries are changing pretty fast. Don't buy a PACK for a car, without buying SEVERAL extra "batteries" of 4 cells each. It is kind of a bit of a problem after a pack has cycled a few dozen times, to marry an individual battery back into the pack. You have to kind of carefully balance it with the others. I use a little hand held 250 watt 5 ohm to bleed small amounts, and have a larger resistor array for more serious stuff. And I use a regular little 12 volt smart charger to "add a little" to a battery.

But over time, the battery business is changing. We're already on order for some Blue Sky 100 AH that have a different SE chemistry and entirely different voltages. I have a LOT of TS laying about fortunately. But it occurs to me that if I was three years down the road, with a scant pack in my car working pretty well, and I did have a cell go bad (approximately inevitable), where would I THEN get a matching battery - even in chemistry and capacity, never mind same batch from the factory?? Putting a BlueSky SE in a pack with TS batteries is out of the question. And that is the transition we've made in a year.

So I would urge you to provision SEVERAL extra 4 cell batteries if you are doing one pack in a car. These batteries have the potential to last 7-10 years at some level of capacity. But inevitably you will have problems with some cells before others. And over that period of time, the current chemistry and manufacturer not only may not be available then, but almost assuredly won't be available then. To have to pull a perfectly good pack and replace ALL the batteries because you cannot find replacements for a single cell seems absurd.

Jack Rickard


----------



## david85 (Nov 12, 2007)

I have been looking at all the ideas about PCM integrated BMS and was wondering if it was really worth all the fuss. Since these batteries don't explode like LiCO2 batteries and are much more forgiving at the top and bottom voltage limits, I think its a little extreme to have an active management for each individual cell that is always working and micromanaging the battery pack.

The only thing my setup has is a low energy cell balancer built into the charger that comes on near the end of the recharge cycle, so there is one wire going to every connection, but after charging, the battery is on its own.

Pulling higher AH ratings out of the cells was something I observed as well in my limited testing. In my case I got about 5% extra, but from cycle life data that SE sent me (which I feel is plausible), the output can peak at 110% by the 50 cycle mark, then drop back down to about 100% by the 500 cycle mark, 90% by 1000-1500, and so on. Not bad IMO, not bad at all.

So you figure the shelf life is about 7-10 years? I think thats reasonable, since the older LiPos can sometimes last 10 years and LiFePO4 should be more stable.


----------



## Coulomb (Apr 22, 2009)

So I wonder what will happen with significant regen if the only balancing is in the (mains) charger. The battery will get most of its charge from the mains, but probably most of the extreme charge current and voltage from regeneration.


----------



## weber (Apr 22, 2009)

jrickard said:


> I've done quite a bit of testing of these batteries, and have about 5000 miles on the car using the THunderskys. ... <much wisdom> ...


Thank you so much for that post, Jack. A distillation of real experience like that is worth its weight in gold.


----------



## speculawyer (Feb 10, 2009)

weber said:


> Thank you so much for that post, Jack. A distillation of real experience like that is worth its weight in gold.


Yeah, I must say this thread has yielded great info lately. Keep up the good work.


----------



## rfengineers (Jun 2, 2008)

david85 said:


> I have been looking at all the ideas about PCM integrated BMS and was wondering if it was really worth all the fuss. Since these batteries don't explode like LiCO2 batteries and are much more forgiving at the top and bottom voltage limits, I think its a little extreme to have an active management for each individual cell that is always working and micromanaging the battery pack.


There is at least some risk. See http://www.batteryvehiclesociety.org.uk/forums/viewtopic.php?t=1825


----------



## Technologic (Jul 20, 2008)

rfengineers said:


> There is at least some risk. See http://www.batteryvehiclesociety.org.uk/forums/viewtopic.php?t=1825


I've seen them short circuit a single cell of Lifepo for over 10 min (the TS brand) and it not do anything but smoke.

Likely the fire originated from the heat itself due to something else.

However active management is not necessary to prevent it if it was a short... relays can be employed, fuses, etc.

I'd suggest that was one in a million shot, or the manufacturer lied about the chemistry ... and probably improper battery placement.


----------



## Guest (Jun 2, 2009)

>There is at least some risk. See http://www.batteryvehiclesociety.org...pic.php?t=1825<

This is an excellent idea. Read it carefully and read between the lines. This IS one of the cases I was referring to about burning a car to the ground. The guy had a "BMS" all right. Shunt balancers mounted on each cell.

I've played with these a lot. And if you are set on them, I'll tell you what to use. On eBay there is a whole bunch of RC helicopter guys using balancers from Hong Kong. Typically, they will "balance" six to eight cells. They do so at the 250 milliamp range. And they are sufficiently well designed that I don't THINK they will go thermal - largely because they are so small. Over the course of a week or two, they will help balance your cells, very slowly. They don't do any particular good while charging, but note that your car speeds a lot of time just sitting around.

I played around with a variety of shunts, most of which I destroyed. I designed and built several prototypes myself of a pretty nifty circuit that could actually shunt 7 or 8 amps and had a very precisely controllable turn on voltage. They could be produced for about $15 per cell. And they would allow you to totally balance your pack during charging.

The problem is the power. Semiconductors tend to change characteristics when faced with rising temperatures. They have a very bad habit of rating these MOSFETs and so forth at very high power levels that are almost entirely based on your ability to heat sink them "properly" which means massively. But there is a limit to how much heat sink you can put on top of a cell, and of course, the heat sink gets HOT. I could get these circuits to work MARVELOUSLY when operating under the expected conditions. And they probably would work.

But if I cranked things up a bit, admittedly to somewhat unrealistic levels, they went into thermal runaway and the current took off to the sky - eventually burning the MOSFET to cinders and really pretty spectacularly. 

My assumption is that if I can take a perfectly good one, and easily get it to burst into flames with a little overvoltage, what would happen if I had one that failed or wasn't good from the beginning. The failure mode is catastrophic.

I can current limit them using somewhat expensive high power resistors. But I've moved the problem. The heat isn't in the heat sink and semiconductor, now it is dissipated in the resistor. But it still gets hot.

Not unmanageably hot on the bench. But quite warm. The problem is, mounting them in a car, first I have 72 cells, that means 72 of them. Second, a car isn't a test bench. It rolls, true enough. But it also vibrates, shakes, rattles, groans, leaps tall speed bumps in a single bound, smashes into pot holes and curbs. Etc. Finding room and securelymounting such a circuit on 72 individual cells is a problem. 

Ok, well, let's just do it at the battery level. Uh-oh. Now I'm doing 4 or 5 amps at 14 volts - we're up to 50 watts when it's working well.

The basic problem is that you have a LOT of cells, and we're dealing with a LOT of power, and in shunting it resistively, that is cummulatively a LOT of heat. Of course, we're charging at night, ideally while sleeping or otherwise distracted by the pleasures of the flesh. Errr... while our car is unsupervised and quietly burning to the ground. Ultimately, the batteries are more reliable than the circuits, however simple, that we design to protect them. And if a $2 MOSFET turns cherry red and gives up the ghost, we have a great possibility of burning a $50K car to the ground. All because someone told us we HAD to have a "BMS" when using LiFePo4.

Regeneration. Currently don't do it as I'm running a DC series motor. We are in the throes of the Mini Cooper Clubman which will do it. I see a LOT Of angst about regeneration overcooking the batteries. I wish. I have some ideas about curing the problem, but unfortunately it is not a problem.

First, the kinetic energy that keeps your car rolling down the road is at its peak efficiency when used as kinetic energy to keep your car rolling down the road. In other words, don't key your regen to your accelerator. Normally, if you take your foot off the accelerator, you will be more efficient letting the car glide than you can ever achieve by putting it back into the battteries.

We will kick in regen as kind of a first detent on the brake pedal. About enough to make the lights come on but before we are actually applying pad to disk. This will let you kick in regen with a slight touch on the pedal, with further pressure required to actually brake. And if you adjust the regen to a level where this results in a pleasant and useful deceleration, it just doesn't make that much current or voltage. You can't take energy out of a pack to accelerate a car, and then convert forward motion BACK to electricity to put in the battery, without a lot of loss. And we tend to brake, using regen, much more gently than we tend to accelerate. The result is that overcharging batteries with regen I personally believe to be not only a myth, but more akin to a fantasy. You can recover a bit of energy with regen. But real world range extension I would look for 7-8%. It's just not going to be a problem. You would have to come out of the garage, and immediately down a 4 mile long 10% grade to be able to get into a position where overcharge would be a problem. If you drive a block and a half before the 4 mile downgrade, it won't be a problem.

Every way I turn on this, it winds up being the CHARGER that is the issue. We're now using a Brusa NLG-11 and it allows us to program as many as 7 stages of charge alternating between constant current and constant voltage. We basically add energy quickly for most of the charge, and then finish with a kind of gentle alternating charge where we bump the voltage a couple of volts, hold it there until the current declines to nothing, and then shut down for 10 minutes or so. Then repeat it. And after doing this a couple of times, we'll simply hold it precisely at our target voltage for an hour at the end.

And the MOST key element, is that we do NOT charge these batteries to the specified 4.25 volts. Indeed, the manufacturer notes that you can extend the life of the cells quite beyond the 3000 cycle limit simply by charging to 4.10 instead.

Real world? We're charging to 3.75 volts. Up to that point, the cells are really remarkably well balanced. After that point, they go completely squirelly with different voltages all over the place, with some zooming to 4.5 while others don't reach 3.95. 

So we just don't go there. We charge hard to about 3.6. And then we charge very gently and in a kind of alternating charge cycle up to 3.75 volts. From 3.75 to 4.25 on my pack, I figure I'm giving up 3 amp hours, or about a mile and a half range, to avoid all the problems. 

I discuss all this in a video at http://www.youtube.com/watch?v=TUzPzX9A4lw.

IN the car DRIVING, I'm watching a couple of items. First is my pack voltage. Small variations at the cell level show up as readily detectable changes when you multiply it by 36. So I start at 129 volts or so, and QUICKLY drop to 3.3 x 36 or about 118 (when stopped). Then it will very gradually and predictably decrease to 108 volts (3.0 x 36), before dropping off a cliff from 108 to 90. Somewhere in that 108 to 90 range, I need to make the garage or source of AC.

Second element is the little balance bargraph. As long as it is within a dot or two of center, my cells are balanced. If it starts to creep away from that, I need to stop and put a voltmeter to the batts to see what's going on. This is very infrequent. But it has happened. Particularly when in the 100 volt range.

I DO have the ability to monitor amp hours into and out of the pack both when driving and charging and similarly kWhrs. That is mostly secondary information. For example, I have 180 Ah of capacity that is REALLY up around 200 ah. So if I have taken out 150 Ah and I'm down around 108 volts that all makes sense.

But if I've taken out 90 Ah, and I'm down around 108 volts, that really doesn't jive. I need to take a closer look.

Metric Minds EVISION is really a good instrumentation system. It's a bit of an install project. And it does cost about $750. Despite my earlier railing about computers, it basically IS one. But it isn't running data lines all over the car. It has a CAN bus from the board to the display. All other connections are analog. And indeed it can get twitchy at times. But it mostly works and at full stop, it reads pretty well. I would have the display brighter. In full sunlight it is not readable.

Jack Rickard

http://evtv.me


----------



## Guest (Jun 2, 2009)

As long as I'm raving on about the problems with these batteries, for those new to the topic, I'm a HUGE fan of them. And again, the reasons are NOT what I thought they would be going in.

Yes, they are lighter. I've got 550 lbs in a car that if I tried to just put that many Trojan 12vs in would come to about 1500 lbs. And they have MORE capacity for that weight. I rather think they do NOT put out as much peak current. That may be the way I have it configured, but that's my sense.

The real benefits are all about life time and charging. We subliminally know a lot about batteries that is just not so with these batteries. Lead acid, Nicad, and Nimh all have some issues we are almost TOO familiar with. Things about completely charging them, and completely discharging them. Even basic lead acid batteries you do not want to charge them halfway and then go drive. Lead sulfation is very real and I've played a lot with the desulfators (they do work by the way). 

LiFePo4 are a bit different. You NEVER have to fully discharge them. And really, you never have to fully RECHARGE them. Not ever.

What this means is that I go to the store, and come home. I plug in the charger, even if I'm going to be there 20 minutes. It's just not that hard to do. Then I go to a friends house, stop by the car wash, and then out to the airport. I plug it in there and charge it as well. Then home, back on the charger.

These batteries like that long flat area in the middle of the curve. They DON'T like the overcharged end, and they don't like the over discharged end. But you don't EVER need to go there, to condition them, to equalize them, to balance them, to avoid sulfation, to recondition them to eliminate memory effect or ANY of that. They just like it in the middle. 

Life of 7 to 10 years? In reality of course I won't know for 7 or 10 years. They do have some calendar deterioration. But all the life cycle data are about how much capacity is lost over the life of the battery. The batteries will still WORK, but you won't have as much range. You are going to lose some by cycling. And you're going to lose some because of the trip of the planet around the sun. But I have more range than I need. By charging early and often, I think that is what we'll get.

Another little misunderstanding is that if you drive the car, and then charge it, you have "used up" "a cycle". No no no no.

In TESTING the batteries, by charging it completely, and discharging it completely, and doing that 1000 times, they can measure the decrease in capacity and show it to you on a graph. 

You do NOT lose nearly as much, by orders of magnitude, if you do not fully discharge the batteries. So if going from 100% to 20% charge is a cycle. Then 100% to 40% twice is not a cycle. Going from 100% to 40% about 10 times, MIGHT be equivalent to a cycle. And going from 100% to 60% about 100 times might be equivalent to "a cycle." Avoiding the two ends, overcharged, and overdischarged, is how you extend life.

And so the most important things to me about these batteries is that they are basically "life of the car", part of the expense of the vehicle, not the operating costs.

And second, they are actually much easier to live with. IF you can get a good charger ( a bit expensive I'm afraid) that you can plug in and walk away from knowing it will CHARGE the batteries without OVERCHARGING the batteries (or burning the car to the rims). If you do so, you just plug it in a lot. No water. No conditioning. No topping. No equalization. No fooling with it.

You're basically down to not running them down too far. It is my belief that this is what the automobile manufacturers are struggling with, and the preoccupation with hybrids and range extension. 

1. Nobody is going to buy a factory made electric car without a manufacturers warranty on the battery.

2. All batteries can be destroyed by overdischarging them, but particularly the LiFePo4 batteries, which are at this point expensive.

3. 10,000 motorists run out of gasoline per day NOW with ICE cars. The general public are idiots, and can't be trusted to not run out of gas. We already know this.

4. Everyone interested in an electric car is concerned about the range.

Simple. We put a gasoline engine in the car with a generator. If the battery voltage decreases to 3.0 volts per cell, we automatically start the gas engine and start charging the batteries. The driver can then get home without us having to buy them a battery pack. And we'll feed on their range fear by making this a FEATURE - more range.

I view hybrids as inheriting the drawbacks and complicating disadvantages of BOTH technologies in the same vehicle. But I would be very surprised to see much in the way of a plug-in electric production car that doesn't sport this feature, and for those reasons.

The alternative is simply to build a cutout in the controller, that disables the car when the static voltage reaches a certain minimum level. This is actually a WEE bit complicated, but can easily be done and is the proper solution. The problem is that if I miscalculate then, I can't just pour in a gallon. I have to have the car put on a flatbed towtruck and taken back to the house. Which would be annoying if I were two blocks away.

Jack Rickard


----------



## Technologic (Jul 20, 2008)

jrickard said:


> Simple. We put a gasoline engine in the car with a generator. If the battery voltage decreases to 3.0 volts per cell, we automatically start the gas engine and start charging the batteries. The driver can then get home without us having to buy them a battery pack. And we'll feed on their range fear by making this a FEATURE - more range.



I think the answer is just a less boxy, non-steel body... that'd fix the range problem... all for a cheap cheap price (battery costs of like $5000 tops for a 200 mile range if done right)

A solid BMS/charger system is way way cheaper than basically everything else.. at least if you're looking at a maximum 110v wall outlet and want to use all of it.

Talking like $300-400 tops for both ($100 BMS $200-300 charger)


----------



## 86Honda (Apr 15, 2009)

I keep hearing about cheap, relaible BMS. I'll definitely be needing such, as my LiFePO4s are on their way. Some of the links go to systems that aren't made to handle my 30 cells, and the maker won't answer my emails.

So where can I really go for a BMS that will do the job with lithiums and not break the bank?


----------



## Guest (Jun 2, 2009)

I agree, in looking somewhat out to the future, you are quite correct.

We are being sold a bill of goods on the cost of the electric car from the manufacturers. 

With just ordinary economies of scale, the price of the car should actually be lower. No exhaust. No radiator/cooling. No smog controls. No "fuel system" (a touchy point with me. Suburbans and Escalades have a fuel pump IN the gas tank. They ALL fail. And it is $1500 to have one replaced.). 

Etc.

But you are also correct in that the core proficiency of our current automotive manufacturers is the pressed steel body. If we want to be light, strong, and efficient, the current technology is of course carbon fiber.

I like the motor in wheel concept. Eliminate the entire drivetrain. PML Flightlink. 

I have been personally STUNNED by the current levels required above 65 mph. I had NO IDEA. So aerodynamiics is important. I don't want an electric car to look like an Aptera frankly. But aerodynamics is important.

But I probably am on a different page with regards to chargers. THE most expensive item in my car after the batteries, and so of course the most expensive single item, is the charger. They are not $100. And as I've described, other than some instrumentation, the charger IS the "BMS" in my system, if you insist on my having one. It's a Brusa NLG511. We are using a NLG513 in the Mini. 

They cost $3600 currently. The motor and controller COMBINED were about that. But that's where you need the technology. I could PROBABLY get a Manzanita PFC-30 to work at $2700, but I like the programmed charge cycles of the Brusa.

How it charges, how difficult it is to charge, how safe your car is while it is charging, etc. all center around the charger, not the rest of the components.
And of course, it is the limitation on charge time as well.

Most people are unaware of it, though it is spelled out on the data sheet, kinda/sorta in English, is that the batteries are NOT the holdup on the amount of time it takes to recharge. I can easily recharge my entire pack in 40 minutes with no harm, and if I'm willing to accept a little shorter battery cycle life, 20 minutes. 

You can recharge these LiFePo4s at up to 3C quite safely. For a 90Ah battery, that's 270 amps. I have them in parallel, so all I need is 540 amps at about 130v and I'm good to go in 20 minutes.

Now I laughingly noted in one video that there isn't any 540 amps anywhere. But it occurs to me that there is. I use 540 amps in the car at about 80 mph. Where does it come from? The batteries.

So if I had batteries, and a controller, and some 2/0 cable, I ought to be able to do this.

So picture a SECOND bank of batteries, a little larger than the one in your car. And you charge THAT slowly with a little charger in the garage. You could pull in, hook up, and in 20 minutes you're near enough fully charged.

This then could be the model for charging stations. Not massive chargers. massive battery banks, with admittedly also large chargers. But the car to charging station interface is about connecting batteries to batteries. Not swapping batteries. And not "charging" for 10 hours. This could be done NOW with current chemistry. No breakthroughs.

In operation for me, I just don't need the range or the quick recharge. But you could do it now, and really rather easily. Separate high current connector on the car. Old abandoned Lead acids in the garage. And any old charger. 

Hook it up. Use a PWM controller to turn it up. Check your voltage. Get a cup of coffee and take a pee. And turn it down. Disconnect and roll.

It will work NOW with the batteries you are using. Anybody could build one. Charge them with solar panels if you must.

Connectors? I would use two L6-30s and wire all four poles to the cable. Have one connector for positive, and one for negative. And hope it doesn't melt. Otherwise, just a couple of posts with wing nuts and standard lugs on the cables would work better, it would just be more to hook up.

Jack Rickard
http://evtv.me


----------



## dimitri (May 16, 2008)

Jack, with all due respect to you ( I read lots of your posts at the TS Yahoo list ) spending $3600 on a charger is INSANE, I don't care how good it is 

My $1000 Zivan NG3 does almost everything ( OK, it has 3 phases, not 7) just as well.

Also, properly designed shunt regulators with feedback bus to the charger and the controller for HVC and LVC do not pose any fire risk. You just need to calculate Wattage properly and use it with correct charger, capable of low current at the end of the charge. Yes, regulators get warm, very warm, but not even close to a fire hazard.

You are telling a good story, but you seem to contradict yourself sometimes...

LiFePo4 pack can be designed properly with matching charger and BMS and it doesn't have to cost same or more than the pack itself.

I am very satisfied with my 40 cell pack, have been running it very hard with overnight charges, all cells are balanced and behave very well. I use Paktrakr, which is awesome, yes, it glitches sometimes due to EMI, but its mostly reliable, and I use my own revision of Brian's Volt Blochers with HVC and LVC feedback bus, feeding back to controller and Zivan charger.

When it comes to battery management, some people tend to go too complex and some too simple, and the truth as usual is somewhere in between, IMHO.

Still, I truly appreciate the time you take to share your info, its very helpful if one can read between the lines


----------



## Technologic (Jul 20, 2008)

dimitri said:


> Jack, with all due respect to you ( I read lots of your posts at the TS Yahoo list ) spending $3600 on a charger is INSANE, I don't care how good it is


spending $1000 on a charger is insane... even if it monitored 75 cells actively too (which his $3600 charger almost certainly doesn't do)

I personally am a HUGE fan of a simple analog BMS for each cell like the goodrum/fetcher for $100 (for 24 cells), because you don't need jack over that utility... it even has a cut off at "empty"

Not to mention the perfect charger for that BMS is just a straight power supply... which as I'm sure everyone realizes 1600w power supplies cost like $40 in parts.


----------



## Guest (Jun 3, 2009)

Well, that's what makes the world go round. Different takes on the same data. 

I would urge you to keep an eye on those shunt regulators. I have tested the Volt Blochers specifically, and indeed have drained a cell dead to zero volts with one of them. I'm not certain why. They are very similar to my LM431 design and ought to work.

As long as the shunts work, they work fine. But if one of them fails, I can assure you they DO pose a fire hazard, whatever your thoughts on the subject, and I've already put out several fires. Small fires on the bench fortunately. That's the point. You're trusting your car to a few semiconductor components which give off enough heat for you to note it, when working properly. Given the environment, I don't buy it. 

As to the chargers, yes, the Brusa is quite expensive. And the Manzanita is quite expensive. And yes, I guess I could rig up a charger with some 50 amp full bridges I have sitting here, that indeed I ordered and have been eyeing for some days.

But note that you can get anything to work while your standing there watching it. The problem is that I need to be able to plug it in and walk away, or it doesn't work for me.

In truth, the only Zivan I have any experience with is the NG1. It was only "programmable" by sending it to the factory. I ordered a new one for a GEM specifying the parameters I wanted. After six weeks, I got an e-mail basically telling me I didn't know what I was talking about and that that would never work for SLAs or GELS. They hadn't even STARTED on it. They specifically noted they don't do LiFePo4s (if that is what I was thinking) So I cancelled the order.

If the NG3 can indeed be programmed for voltage and current, switches between constant voltage and constant current, and you get 3 stages, and terminates the process reliably, it would indeed be overkill. And I have had anomalies with the Brusa - it will magically decide the input voltage is about 350 vac and terminate and I've never quite tracked that down. Fortunately it is quite rare.

So I don't agree that $3600 for a charger is insane. But on the other hand, I don't have to carry a torch for them either. it's well made and has features I like, but I'd love a $600 version. If you can take that $40 worth of parts and make it do all that reliably, sign me up at $600. That ought to make you a pretty handsome profit.

What I don't understand about the Brusa is how it measures the battery voltages. And I would note that it doesn't do it precisely accurately. It typically reads a volt beyond what I've set before it switches to constant current. But the problem is that it is a little difficult to measure the voltage of a battery when you are applying a charge voltage to it. 

I can only guess they have some way of dropping the voltage momentarily until current flow drops to zero, and measuring it at that point, bringing it back up to continue charging. But if I WAS to put some bridges and caps together into a power supply, I could probably make it programmable with an Arduino or something similar as a microcontroller, but how do I measure voltage of the BATTERY accurately WHILE I'm charging it??? It's kind of difficult to ramp the voltage output down until the current zeros out, take the value, and then ramp it back up to the voltage we're supposed to be charging at, once per second or so. And the batteries move around, slowly, when you do so.

And this IS the time your cable drops, mentioned a page or two back, start to get into the game to mess you up.

So I don't have a good charger design in mind. And that leaves me pretty much with a Brusa or Manzanita, and currrently I favor the Brusa.

Sorry, Zivan isn't happening for me. I have taken an interest in DeltaQs, but so far haven't seen anything in useful voltages - say 130-200 volts.

So I'm still looking for solutions and receptive to any information you guys have. But the propensity to repeat myths and admonitions endlessly starts to look like the usual attempt to "type yourself smart" by repeating each others advice. And that doesn't work for me. If I can go into the back of the garage with a piece of wire and a five gallon bucket and repeat your experiment myself, much better. The way this started was NOT to criticize the guy for doing it, it was to try to understand what useful information was being gained. The process was admirable. I didn't understand the test objective.

And I think he was actively learning some things I've kind of previously discarded as unimportant ( a view ALWAYS subject to revision in the face of new evidence I would note). I not only reserve the right to my opinion, but to change it regularly, frenetically, and in the face of all reason.

I've got a great design for a flying capacitor "charge shuttle" that will balance these cells quite well. But with the PCBoard, the clock, the drivers, the mosfets, and the caps, it's about $400 in components to do four cells. Oh, and sufficiently abused, it indeed bursts into flames as well.

Jack Rickard


----------



## david85 (Nov 12, 2007)

Jack you are full of info, but you are wearing me out with your long posts lol.

I can't really find much wrong with what you posted though, I think I agree with everything you mentioned.

Perhaps monitoring of individual cells is a good idea so you know when to deal with problems before they get out of hand, but active responce BMS on each cell is probably not the best way to go anymore (if it was ever). If a cell is going to blow, a BMS can't save it and it will have to be repaced. I remember the chinese supplier for my LiFePO4 batteries also mentioned that they tried to use the 1 per cell approach to BMS and they proved unreliable. This in fact was the original standard borrowed over from LiPo battery technology, and its still used by companies like Kokam in that role.

The chargers I have now uses a BMS circuit built into the charger itself, and it seems to work great.

I second what you say about cells working better if you stay within certain limits for top and bottom of the cycle. In truth it has been known among RC model airplane flyers that even LiPo cells can stay in balance indefinately if you only kept them within the minimum and maximum voltage and NOT allow them to pump out insane amounts of current.

Even the old spiral cell LiCO2 cells can self balance if you are careful enough to use a good smart charger that will not overcharge them.

My 48 cell charger was about $1500USD (made in china). A bit bulky, but it seems to be overdesigned, so we'll see how well it holds up.


----------



## dimitri (May 16, 2008)

> I would urge you to keep an eye on those shunt regulators. I have tested the Volt Blochers specifically, and indeed have drained a cell dead to zero volts with one of them. I'm not certain why. They are very similar to my LM431 design and ought to work.
> 
> As long as the shunts work, they work fine. But if one of them fails, I can assure you they DO pose a fire hazard, whatever your thoughts on the subject, and I've already put out several fires. Small fires on the bench fortunately. That's the point. You're trusting your car to a few semiconductor components which give off enough heat for you to note it, when working properly. Given the environment, I don't buy it.


Only defective or improperly assembled module could drain the cell. Quality control is absolutely critical. I tested each one of my modules several times using regulated bench power supply, to make sure there are correct HVC and LVC points and expected shunt current, and lack thereof when voltage is normal. I also intend to perform regular inspections, by monitoring end of charge once in a while. I did it last night and observed all red LEDs come up within 5 minutes of each other while charger was only putting out 1.5 amps. Modules heat up to 120F, which is quite safe IMHO.


----------



## Technologic (Jul 20, 2008)

86Honda said:


> I keep hearing about cheap, relaible BMS. I'll definitely be needing such, as my LiFePO4s are on their way. Some of the links go to systems that aren't made to handle my 30 cells, and the maker won't answer my emails.
> 
> So where can I really go for a BMS that will do the job with lithiums and not break the bank?


I linked this before... you can simply use 2 of them 15 each or just add 6 from one of them onto the end of the 24... either will work (it's expandable for basically ever... and can be sent to 1 charger)

http://www.tppacks.com/products.asp?cat=26


----------



## dimitri (May 16, 2008)

Technologic said:


> I linked this before... you can simply use 2 of them 15 each or just add 6 from one of them onto the end of the 24... either will work (it's expandable for basically ever... and can be sent to 1 charger)
> 
> http://www.tppacks.com/products.asp?cat=26


 
While TPPacks is an excellent system for bikes and smaller packs, you need to understand its limitations when used with large prismatic cells. Most important is limited max charging current and limited shunting ability for balancing. 

Just make sure you calculate how long it would take to charge and balance your pack and what charger you will use with it. Only properly matched system will work well, if not, you have many risks on your hands.


----------



## Technologic (Jul 20, 2008)

dimitri said:


> While TPPacks is an excellent system for bikes and smaller packs, you need to understand its limitations when used with large prismatic cells. Most important is limited max charging current and limited shunting ability for balancing.
> 
> Just make sure you calculate how long it would take to charge and balance your pack and what charger you will use with it. Only properly matched system will work well, if not, you have many risks on your hands.


TPPacks has different shunt resistor possibilities for larger packs... and apparently all it takes is more time to charge a larger pack with the standard shunt resistor... however you can bump the shunt resistor up to a 1amp end of charge balancing if you cool it properly.

I don't see the risk in it... assuming you only drive when the pack is actually completely full (all lights on)... 

The alternatives ($2000+ BMS's?) can't do much more than the Goodrum/fetcher... even if they claim they can.

There's more than a few people (few dozen maybe?) using them in large strings of batteries (100+AH per string) or prismatics.


----------



## dimitri (May 16, 2008)

Technologic said:


> There's more than a few people (few dozen maybe?) using them in large strings of batteries (100+AH per string) or prismatics.


Do you know what charger models these people use with it? What is their max charge current?

The schematic posted on TPPacks shows power transistor which passes all charging current mounted without any heat sink. That transistor ( STP160N75F ) is capable of 120Amp current, but it can produce up to 300 Watts of heat. How much current do you think its capable of without heat sink? How big of a charger can one connect to it before they see smoke coming out? With 100Ah+ pack size, one would need 15-20 amps current to charge all night long, anything less is too long.

The doc doesn't say a word about charger and current limits. How do you expect a regular person who is not an EE to buy this product and use it without starting a fire?

Again, I am not putting down TPPack, its an excellent DIY product for those who know what they are doing, but please do not market it as a complete BMS for general public. It needs a lot of modifications and marketing work to be used in large EVs, at which point it will not be so cheap anymore, so there is no free lunch here...


----------



## Technologic (Jul 20, 2008)

dimitri said:


> Do you know what charger models these people use with it? What is their max charge current?
> 
> The schematic posted on TPPacks shows power transistor which passes all charging current mounted without any heat sink. That transistor ( STP160N75F ) is capable of 120Amp current, but it can produce up to 300 Watts of heat. How much current do you think its capable of without heat sink? How big of a charger can one connect to it before they see smoke coming out? With 100Ah+ pack size, one would need 15-20 amps current to charge all night long, anything less is too long.


This was all covered in the thread over at endless sphere... the BMS has a top end of 30 amps ... per cell during charging.. (with no sinks)

20 amps would be a huuuuge pack (ie. a pack with what... 160AH/cell? or more?) and even at 160AH cells it'd still only take like 8 hours with a 20 amp charging current

You can use a 3.2 ohm resistor (1 amp balancing charge) if you use a proper heatsink/fan




> The doc doesn't say a word about charger and current limits. How do you expect a regular person who is not an EE to buy this product and use it without starting a fire?


What makes you think an EE is even needed? Anyone, if you didn't understand how it worked, would merely need to ask someone... it was even discussed here before in this same thread how the BMS functions. It's simple, efficient and can be somewhat adapted for different build models (with low cutoff being either 2.7v or 2.1v... or through proper additional components increased to 2.5v)



> Again, I am not putting down TPPack, its an excellent DIY product for those who know what they are doing, but please do not market it as a complete BMS for general public. It needs a lot of modifications and marketing work to be used in large EVs, at which point it will not be so cheap anymore, so there is no free lunch here...


Modifications maybe... marketing?????? why on earth would marketing be necessary to make it usable? You mean ease of use?

The modifications for a larger EV (ideal solution as your goal) wouldn't even double the price... though you would need new boards.
What suggestions do you think are necessary? 50amp charging currents and prepopulated boards?

Your average 110v outlet couldn't output more than 10-15 amps into MOST 100+v builds ... planning to do a 25kwh pack off 220v? if so just make something yourself... swap out the design and improve it slightly with better components (learning enough engineering to do that will be the least of your worries in such a build... good luck finding a proper regen motor/controller).

I'd have to relook at the design... but could you point out at least one flaw in it? Sure it's not active, but that isn't necessary either. You don't need a DSP monitoring and controlling everything to make a simple thing like Lifepo charging safe. The bypass balancing design they employ is simple and effective.


----------



## dimitri (May 16, 2008)

You basically covered everything for me already . To use TPPack BMS someone should:

- buy PCB and parts from separate suppliers
- get familiar with schematics and assembly
- learn how to use small soldering iron
- assemble everything and test it, for which you also need to buy a regulated bench power supply
- install spaghetty wiring going from PCB to each cell, in many EVs that means running 20+ thin wires from one end of the car to another
- hope that EMI won't screwup voltage reading on wires running across the car and trigger false LVC or HVC events
- find suitable charger that will work with it
- read lots of posts on various forums to make sure you are doing it right

I mean this is all very cool DIY project and I have done it myself and enjoyed every minute of it, but let's face it, its not for everyone. So when people ask for BMS options and you post the link to TPPacks, just make sure to include 8 point listed above, so people can gauge their skills and compare apples to apples.


----------



## Technologic (Jul 20, 2008)

dimitri said:


> You basically covered everything for me already . To use TPPack BMS someone should:
> 
> - buy PCB and parts from separate suppliers
> - get familiar with schematics and assembly
> ...


Well many of those are unfortunate side effects for ANY BMS system... especially the spaghetti wiring from each cell (which is... of course, always necessary for this type of REAL BMS).

any power supply will work (like the $240 1600 watt chargers I've mentioned before)...

Technically your car's charger is a bench supply already (at least if it's any good)  but you can always buy a cheap one on ebay for $40.

Now a soldering iron... I hope there's no EV DIYers needing to learn soldering  if so..... 

I'm interested in any actual legitimate alternatives, besides trusting in the chargers coming out of china... which is meeeeeh on the "trust" scale. Not to be a jerk, but I seriously don't know of any actual battery management systems + chargers less than $3000 for lifepo... and IMO that's enough reason to suggest the Goodrum


----------



## JRP3 (Mar 7, 2008)

Actually a full EV conversion can be done quite successfully with no soldering at all. I'm also leaning more towards Jacks approach, split the pack to monitor any discrepancy and not worry about cell level protection or monitoring. He makes good arguments, but he's also saying what I want to hear


----------



## Guest (Jun 3, 2009)

Ok. I'll be brief. Don't solder ANYTHING in your car. Another thing I've learned the hard way. It SEEMS like the GOOD way to do it, but remember the car shakes, rattles and rolls. 

Bottom line they break.

The cheap looking plastic connectors and crimps you see all over cars, - its not what you think. They are actually THE thing because they're flexible, they give, the wiring moves around and they stay connected. They LOOK cheap. They LOOK flimsy. 

The solder joint is flimsy. It cannot take the jostle. Wave soldered components are ok. But hand done solder joints or wires wrapped around terminals and soldered simply break off.

Jack Rickard


----------



## rfengineers (Jun 2, 2008)

jrickard said:


> Ok. I'll be brief. Don't solder ANYTHING in your car. Another thing I've learned the hard way. It SEEMS like the GOOD way to do it, but remember the car shakes, rattles and rolls.
> 
> Bottom line they break.
> 
> ...



And remember, NEVER speak in absolutes!

Jack, I am going to qualify your statement. Never solder anything in a car unless you know what you are doing and have the proper tools. If you have been professionally trained to solder devices used in military fighter jets (as I have) or for launch into space (as my wife has) then you MIGHT be the exception to this rule.

Thanks for reminding me why I don't offer my electronic devices as kits!


----------



## CroDriver (Jan 8, 2009)

Don't want to read to read the entire thread...

Could someone just say if the cell does what's claimed or not? 

(Yes, I'm lazy and it's pretty hard to me to read long texts in english...)

Thanks


----------



## Technologic (Jul 20, 2008)

jrickard said:


> Ok. I'll be brief. Don't solder ANYTHING in your car. Another thing I've learned the hard way. It SEEMS like the GOOD way to do it, but remember the car shakes, rattles and rolls.
> 
> Bottom line they break.
> 
> ...


I've soldered in car environments for yeeeeears... never can I remember a joint failing (especially one that is on a PCB).

At any rate I'm not suggesting the goodrum is the answer, but there's not a lot of options.


----------



## Technologic (Jul 20, 2008)

CroDriver said:


> Don't want to read to read the entire thread...
> 
> Could someone just say if the cell does what's claimed or not?
> 
> ...


it does a tad bit better than it's claim... at least up to my testing .

It seems to have a 85-90% usable range off a full charge (which I haven't been able to completely perform)


----------



## weber (Apr 22, 2009)

jrickard said:


> The batteries do sag under load and it is rather variable.
> ...
> The temperature actually doesn't matter. Yes, I'm familiar with what it does, but in the end, you'll come to the same conclusion. Track it and compare it all you want, in the end the curve is the curve.


Yes. We measured the rested voltage of a near fully charged TS cell at widely different temperatures and found no significant change. However temperature has an enormous effect on internal resistance, i.e. on how much they sag under load. With a sustained heavy load, at some point in time the voltage actually begins _rising_ due the cell's self-heating.


----------



## david85 (Nov 12, 2007)

The only time I ever saw automotive wiring fail is when it was not wrapped and secured properly. Inline connections can be re enforced with head shrink tubing that spreads the stress. Large amounts of wiring also needs to be wrapped together and secured to the car chassis to prevent vipration from doing any harm.

Having said that, I've worked on rattly diesel vehicles that shake more than any EV, and never saw any reason to fear solder joints.

Salt corrosion is also a major concern in my neck of the woods, so crimp connectors are simply a no-no for me.


----------



## Guest (Jun 4, 2009)

ack, I am going to qualify your statement. Never solder anything in a car unless you know what you are doing and have the proper tools. If you have been professionally trained to solder devices used in military fighter jets (as I have) or for launch into space (as my wife has) then you MIGHT be the exception to this rule.

Thanks for reminding me why I don't offer my electronic devices as kits!
__________________

Errr... ok. But yes, I learned to solder in the United States Navy, working on F4 fighter jets. And followed up with 12 years working for defense contractors.

Solder is relatively brittle and in all cases joining two and some times three dissimilar metals. I can tell you guys know best. 

I do agree I LOVE the heat shrink. We found some heavy duty milspec heat shrink with the adhesive that melts on eBay and it is just everywhere in the car.

No I haven't had much problem with PCBs and solder. But the wires going to them have been a problem. The plastic connectors and crimps work much better, and that's why you find them all over a modern automobile.

Jack Rickard


----------



## dimitri (May 16, 2008)

> I'm interested in any actual legitimate alternatives, besides trusting in the chargers coming out of china... which is meeeeeh on the "trust" scale. Not to be a jerk, but I seriously don't know of any actual battery management systems + chargers less than $3000 for lifepo... and IMO that's enough reason to suggest the Goodrum


I'll try to bring this back to topic 

Techno, I never intended to make you look like a jerk , I was simply trying to show that TPPacks is a DIY system, not an off shelf product, you get what you pay for. 

You are right, unfortunately, that we don't have too many BMS choices, so every suggestion is valuable, just needs to be judged on the same level of features, capabilities, etc. not just pure cost of components.

I know that Brian is working on next revision of Volt Blochers with additional HVC and LVC functions, and Dave Kois is offering a BMS on his Web site, which is also new to the market and yet to be proven.

Meanwhile, I will try to put my money where my mouth is and offer my own implementation of BMS based on my experience with TS cells. See my post in Classifieds section.

I have no intention to compete with anyone else, and I have no means for mass production, I am just offering modules that I invested time and money into, and have surplus of PCBs that I ordered for myself. I have strict specs and requirements to ensure minimum risk and maximum safety.

And by all means, if you can assemble PCBs and want to save money, please buy TPPacks kit or Volt Blochers kit, those are great DIY choices.


----------



## TheAtomicAss (Feb 19, 2009)

jrickard said:


> So I would urge you to provision SEVERAL extra 4 cell batteries if you are doing one pack in a car. These batteries have the potential to last 7-10 years at some level of capacity. But inevitably you will have problems with some cells before others. And over that period of time, the current chemistry and manufacturer not only may not be available then, but almost assuredly won't be available then. To have to pull a perfectly good pack and replace ALL the batteries because you cannot find replacements for a single cell seems absurd.
> 
> Jack Rickard


Sounds like good advice... But if a single cell in a pack failed, I would think it would be good economy to simply remove the affected cell and live with a slightly lower-capacity pack. Assuming one wasn't too fond of the idea of keeping and maintaining multiple replacements.


----------



## yamez4u (Feb 10, 2009)

My thought on this was to buy 4 extra and use them as a single 12 volt battery for 12v loads. That way in the future if need be you would always have four spares you could raid from the 12v system.


----------



## JRP3 (Mar 7, 2008)

I had a similar thought though that makes for a pretty expensive and over sized 12 volt battery in my case. I'll probably just take my chances, hoping weak cells will show themselves within a year and get replacements for them if needed.


----------



## Nomad (May 8, 2009)

Technologic said:


> Your average 110v outlet couldn't output more than 10-15 amps into MOST 100+v builds ... planning to do a 25kwh pack off 220v? if so just make something yourself... swap out the design and improve it slightly with better components (learning enough engineering to do that will be the least of your worries in such a build... good luck finding a proper regen motor/controller).


Maybe I'm not understanding something here, but if a battery pack is AH*Total Voltage Then a 320v System using LiFePo4 @ 200AH would be a 64kW package and they offer Motors and controller for those setups.


----------



## yamez4u (Feb 10, 2009)

If you go VAC most setups want voltage in that range AC55 and AC90 both want 312 volt battery packs.(1)(2) 98 cells X $240 a piece would run you $23,520 If you could manage to get all those batteries in a car I'm guessing you would have close to 200 mile range. Some of the factory Ford Ranger guys are getting 100 mile range with 100AH packs. 

(1) http://www.bev.com.au/diy.htm
(2) http://www.evcomponents.com/ProductDetails.asp?ProductCode=AC55



Nomad said:


> Maybe I'm not understanding something here, but if a battery pack is AH*Total Voltage Then a 320v System using LiFePo4 @ 200AH would be a 64kW package and they offer Motors and controller for those setups.


----------



## Nomad (May 8, 2009)

yamez4u said:


> If you go VAC most setups want voltage in that range AC55 and AC90 both want 312 volt battery packs.(1)(2) 98 cells X $240 a piece would run you $23,520 If you could manage to get all those batteries in a car I'm guessing you would have close to 200 mile range. Some of the factory Ford Ranger guys are getting 100 mile range with 100AH packs.
> 
> (1) http://www.bev.com.au/diy.htm
> (2) http://www.evcomponents.com/ProductDetails.asp?ProductCode=AC55


Oh I know you can get them all into a car. Or a truck rather. Into a car you need to take it down to frame. And it's around $200 a piece. Not saying it isn't expensive, but the point was they make controllers with regen for setups like that.


----------



## Guest (Jun 22, 2009)

Well, a coupla things. We're doing AC with the Mini Coooper Clubman project using a MES-DEA controller and motor from metricmind.

Yes, most of the ac induction motor/inverter setups like higher voltages and we plan this one for 24 four cell "batteries" or 96 cells for 316 nominal volts. But power is power. If you double the voltage, you halve the current required to deliver the same power to the motor. 

So if you are accustomed to 144 volts and maybe 550 amps at the high end, at 288 volts that would look more like 275 amps. And so the 200 Ah cells would be overkill, and in this case quite capable of delivering much more current than our controller would.

96 200Ah cells would certainly be nice for range, as that would give us about 275 miles. But performance would suffer from the weight and it would pretty much fill up the car.

We are going to use the newer BlueSky SE batteries in a 100 ah form factor. 
These cells use the Aleees LFP NCO cathode material (nanococrystelline olivine) which allows a higher power to weight (about 157 mAh/g) as opposed to the Thundersky LFP at 130 mAh/g. And so these 100 Ah cells are about the same size and weight as the Thundersky 90Ah.

Total pack will then be about 34560 wHr or 138 miles max or 110 miles at 80% DOD. It should weigh 720 lbs or thereabouts and the cost will be a little over $11,000 for the battery pack.

I guess what I was offering before walking off into the weeds of all that detail, is that higher voltages lessen the requirement for current capability. We could easily have done this car with 60 Ah batteries and it would work fine. And the 200 Ah cells, beyond being just too much weight for the project, just wouldn't be used by the controller. At 300v, the controller would be unlikely to even peak at the 400 amp rating of the controller. 

We have the intro video up as well as the first video on brakes and wheels for the clubman. 

Jack Rickard
http://evtv.me


----------



## Nomad (May 8, 2009)

jrickard said:


> We are going to use the newer BlueSky SE batteries in a 100 ah form factor. These cells use the Aleees LFP NCO cathode material (nanococrystelline olivine) which allows a higher power to weight (about 157 mAh/g) as opposed to the Thundersky LFP at 130 mAh/g. And so these 100 Ah cells are about the same size and weight as the Thundersky 90Ah.


Same in cost?


jrickard said:


> Total pack will then be about 34560 wHr or 138 miles max or 110 miles at 80% DOD. It should weigh 720 lbs or thereabouts and the cost will be a little over $11,000 for the battery pack.


How did you figure out your range? This is something I've still strugled with and I've seen a million different ways to do it but the most common is take your mpg *3 (If your building a 33wK pak)


----------



## Guest (Jun 22, 2009)

Actually, I believe the last I paid for Thundersky 90 ah was about $135 per cell. These BlueSky's are coming in at about $110 plus some shipping which was a little vague. So yes, about the same cost.

Jack Rickard
http://evtv.me


----------



## ClintK (Apr 27, 2008)

Nomad said:


> Maybe I'm not understanding something here, but if a battery pack is AH*Total Voltage Then a 320v System using LiFePo4 @ 200AH would be a 64kW package and they offer Motors and controller for those setups.


Double check your units... 320v x 200AH is a 64kWH pack. Any motor that can handle 320v can handle that pack.

There are 64kW package Motors/Controllers which would drain that pack in 1 hour if run continuously at peak output.

I think most LiFePO4 cells can handle 3C meaning 3*Capacity which would be 600 Amps. Or 320v x 600 Amps which means that battery pack can deliver (in theory) 192kW of power continuously to a motor/controller.


----------



## Guest (Jun 22, 2009)

Nomad said:


> Same in cost?
> 
> 
> How did you figure out your range? This is something I've still strugled with and I've seen a million different ways to do it but the most common is take your mpg *3 (If your building a 33wK pak)


I'm not sure I follow your calculation. Range involves vehicle weight, aerodynamics, and rolling resistance, and your available power, or pack size.

In this case, I'm using a bit of a guess. We're pobably averaging about 225 to 230 watt hours per mile on the Speedster which is 2190 lbs finished. I think we are looking at about 3200 lbs finished on the Mini Cooper. But it has a more efficient drive train and transmission, very good mileage as an ICE car (37 highway) indicating good rolling resistance and aerodynamics, and so I'm guessing at an average of 250 wH per mile. With a 34kWh pack, and 80% DOD, that would indicate about 110 miles to 80%.

One VERY rough calculation I've used in the past, and been more or less in the ballpark, is to take your pack energy (you propose 33 kWh) and divide it by 8 kWh and assume that equals a gallon of gas. Multiply the number of pseudo gallons then by your average mpg. 33/8 = 4.125. The mini probably averages 31 mpg city/highway so 4.125 x 31 = a little over 127 miles max. 80% of that would be 102 miles. That would get us into the same range roughly.

I think we may do just a bit better perhaps. The Getrag transmission has THREE over drive gears in this thing. My experience is that once you get rolling these taller gear ratios work very well with electric motors and you can kind of idle along very nicely using very little energy.

AC motors can indeed rev quite high, but if you notice the curves the torque is always better in the 1500-2500 range. I have read some well intentioned posts regarding lugging your motor and heat, but they do not match my observations. But we do have about 250 cfm of air going right down the throat of the Netgain in the Speedster, and the AC will actually be liquid cooled.

Either way, my most comfortable ride seems to be at 1800-2000 rpm. And I think with this Getrag six speed, I'll be able to live there more.

Jack Rickard
http://evtv.me


----------



## Guest (Jun 22, 2009)

ClintK said:


> Double check your units... 320v x 200AH is a 64kWH pack. Any motor that can handle 320v can handle that pack.
> 
> There are 64kW package Motors/Controllers which would drain that pack in 1 hour if run continuously at peak output.
> 
> I think most LiFePO4 cells can handle 3C meaning 3*Capacity which would be 600 Amps. Or 320v x 600 Amps which means that battery pack can deliver (in theory) 192kW of power continuously to a motor/controller.


I think you are going to have a difficult time locating an AC motor/controller combination that can handle 192kW of continuous power. But if you found one, and you did run it continously at that rate, you'd be going at a speed of about 700 miles per hour, and would have a very impressive range in that hour.

We are using a 30kw package. That is the continous rating. It can peak, in theory, at about 400 amps and 300 volts for 120kw which is about 160 hp. But I wouldn't see it doing it for more than a 10 second acceleration, which should get the car to its maximum top speed.

Will a 100 Ah battery put out 4C? I guess we'll see. But if it peaks at 300 amps, I think we'll be rolling pretty well with that. I want snappy performance but I doubt we'll appear at NEDRA.

Jack Rickard
http://evtv.me


----------



## Nomad (May 8, 2009)

ClintK said:


> Double check your units... 320v x 200AH is a 64kWH pack. Any motor that can handle 320v can handle that pack.
> 
> There are 64kW package Motors/Controllers which would drain that pack in 1 hour if run continuously at peak output.
> 
> I think most LiFePO4 cells can handle 3C meaning 3*Capacity which would be 600 Amps. Or 320v x 600 Amps which means that battery pack can deliver (in theory) 192kW of power continuously to a motor/controller.


I always forget that damn h


----------



## Nomad (May 8, 2009)

jrickard said:


> I think you are going to have a difficult time locating an AC motor/controller combination that can handle 192kW of continuous power. But if you found one, and you did run it continously at that rate, you'd be going at a speed of about 700 miles per hour, and would have a very impressive range in that hour.


They are there... I'm looking at a 200kW Continuous with a 430kW Peak. Comming in at a ripe 700lbs..

But the 75kW system can burst up to 200kW Pulling 700a 320v weighting only 300lbs 

I think I'm starting to understand all this stuff now.. Before I was getting kW and kWh all mixed up in my head. But it's starting to come together. Thx for the corrections.


----------



## Nomad (May 8, 2009)

jrickard said:


> Actually, I believe the last I paid for Thundersky 90 ah was about $135 per cell. These BlueSky's are coming in at about $110 plus some shipping which was a little vague. So yes, about the same cost.
> 
> Jack Rickard
> http://evtv.me


I'm sorry man, I got lost again.. 

The 100AH 3.2v Batts are coming in at 3.2kg's with 100AH's SO... 
mAh/g = 100,000/3200 ~ 31.25?? I must have missed something major here.


----------



## Nomad (May 8, 2009)

jrickard said:


> I'm not sure I follow your calculation. Range involves vehicle weight, aerodynamics, and rolling resistance, and your available power, or pack size.


33kWh in a gallon of gas.
EV is 3.5 times more eff.
so pak/gas*3.5*(Pervious MPG)

Just made sense, but I could be way off. I'll take a look at your fourmula and see if it works out on others.

Well... no thats right... I'm getting 133.36 range for your setup. @ 80DoD it's 106ish.


----------



## Guest (Jun 22, 2009)

Nomad said:


> I'm sorry man, I got lost again..
> 
> The 100AH 3.2v Batts are coming in at 3.2kg's with 100AH's SO...
> mAh/g = 100,000/3200 ~ 31.25?? I must have missed something major here.


I shouldn't have thrown that out there. I've been reading too much about batteries. It just shows the relative power density of LFP and LFP-NCO.

Basically, the LFPNCO are up to a theoretical power density of 157 mAh per gram. That's not the whole BATTERY, it is just the LFP NCO cathode material compared to the LFP cathode material.

The bulk of the weight of the battery is in the aluminum foil cathode current collector, and the copper foil anode current collector. But the chemistry of the battery itself is in the Lithiium Iron Phosphate cathode (a thin layer of material on both sides of the aluminum foil), and the carbon/graphite anode material (think layer on both sides of the copper foil). 

So higher power density on the cathode material itself. But not the way to calculate the power of a battery by its weight.

Jack Rickard
http://evtv.me


----------



## Guest (Jun 22, 2009)

Nomad said:


> They are there... I'm looking at a 200kW Continuous with a 430kW Peak. Comming in at a ripe 700lbs..
> 
> But the 75kW system can burst up to 200kW Pulling 700a 320v weighting only 300lbs
> 
> I think I'm starting to understand all this stuff now.. Before I was getting kW and kWh all mixed up in my head. But it's starting to come together. Thx for the corrections.


What system are you looking at? Do you have a link?

Jack Rickard
http://evtv.me


----------



## Nomad (May 8, 2009)

jrickard said:


> What system are you looking at? Do you have a link?
> 
> Jack Rickard
> http://evtv.me


It's an AC Motor

http://www.china-electricmotor.com/ArticleShow.asp?ArticleID=154


----------



## Nomad (May 8, 2009)

jrickard said:


> I shouldn't have thrown that out there. I've been reading too much about batteries. It just shows the relative power density of LFP and LFP-NCO.
> 
> Basically, the LFPNCO are up to a theoretical power density of 157 mAh per gram. That's not the whole BATTERY, it is just the LFP NCO cathode material compared to the LFP cathode material.
> 
> ...


HAHA.. you know after reading that I'm having a duh moment.. Why include the the casing for the batteries when calculating that. Where did you find those kind of details?


----------



## JRP3 (Mar 7, 2008)

Nomad said:


> But the 75kW system can burst up to 200kW Pulling 700a 320v weighting only 300lbs


Only 300lbs Just to compare, the ACPropulsion peaks at 150kW and weighs 110 lbs, Tesla Roadster peaks over 220kW and weighs 75lbs. Not that you can get either of those, but the power to weight ratio you are looking at isn't great, and from the link you gave it looks like the 75kW system peaks at 160kW, not 200.


----------



## Nomad (May 8, 2009)

JRP3 said:


> Only 300lbs Just to compare, the ACPropulsion peaks at 150kW and weighs 110 lbs, Tesla Roadster peaks over 220kW and weighs 75lbs. Not that you can get either of those, but the power to weight ratio you are looking at isn't great, and from the link you gave it looks like the 75kW system peaks at 160kW, not 200.


If you have something better with a buy in now option I'm listing.

And the Tesla is Rated at 185 kW but at 75 lbs thats great.
http://www.teslamotors.com/performance/tech_specs.php


----------



## JRP3 (Mar 7, 2008)

Nomad said:


> If you have something better with a buy in now option I'm listing.


Wish I could help you.


> And the Tesla is Rated at 185 kW but at 75 lbs thats great.
> http://www.teslamotors.com/performance/tech_specs.php


You are correct, my mistake. There were some incorrect European numbers floating around claiming 225 kW for a while.


----------



## Nomad (May 8, 2009)

JRP3 said:


> Wish I could help you.
> 
> You are correct, my mistake. There were some incorrect European numbers floating around claiming 225 kW for a while.


From what I've seen they used alummium sp? for the casing.

It could be argued that most of the motors could be refitted to be lighter, but you need them to have some weight behind them right? I mean.. 75 lbs twisting 2000lbs car just doesn't sound right.


----------



## JRP3 (Mar 7, 2008)

I don't know, it seems to work pretty well for Tesla 
There are aluminum versions of industrial motors, I don't know the construction of the ones you linked to. One of the problems with many industrial motors is they usually are not concerned with weight, just durability when running continuously under load for hours or days on end.


----------



## Nomad (May 8, 2009)

JRP3 said:


> I don't know, it seems to work pretty well for Tesla
> There are aluminum versions of industrial motors, I don't know the construction of the ones you linked to. One of the problems with many industrial motors is they usually are not concerned with weight, just durability when running continuously under load for hours or days on end.


Yay for Cast Iron. 

But thats news for us. Still I bet I could shave 100lbs off by "letting it breath" some. 

I bet Tesla has that motor bolted down with 30 plus bolts as well.. I guess I should really ask the whitezombie guy how be puts down that much torque w/o breaking something.


----------



## JRP3 (Mar 7, 2008)

Nomad said:


> I bet Tesla has that motor bolted down with 30 plus bolts as well..


Or not


----------



## yamez4u (Feb 10, 2009)

What did you pay for the "MES-DEA controller and motor from metricmind." what kw is the setup?


----------



## Technologic (Jul 20, 2008)

yamez4u said:


> What did you pay for the "MES-DEA controller and motor from metricmind." what kw is the setup?


You probably don't even want to know...

Think 5 figures.


----------



## Sweet (Jun 23, 2009)

Nomad said:


> It's an AC Motor
> 
> http://www.china-electricmotor.com/ArticleShow.asp?ArticleID=154


 http://www.china-electricmotor.com/Products.asp?BigClassName=Vehicle motor


----------



## JRP3 (Mar 7, 2008)

Nice, 50kw continuous, 160 max, 110lbs. Torque seems a bit low though. Price?


----------



## Guest (Jun 23, 2009)

yamez4u said:


> What did you pay for the "MES-DEA controller and motor from metricmind." what kw is the setup?


We got the MES DEA 200-250 motor and the TIMS 600 controller. I believe it was a little over $12,000 for the pair. The motor is nominally 30 kw. The controller will do 400 amps peak at 400 volts or about 160kw. Both are water cooled.

Like everything we've seen from the German/Swiss area, these are beautiful pieces of equipment. My only concern is spares. Hopefully we won't need any. We did receive a DC-DC converter DOA from them at one point. But it was replaced within about 3 weeks.

The AC induction world is indeed more expensive. We have talked with AC propulsion. They wanted us to buy 5 at $25,000, which I did agree to do. But then they seemed a little confused about how we would program the battery charging parameters for our LiFePo4 cells, and I did not get a great feeling about their "technical support" capabilities. So we went away.

I think the MES-DEA system is quite a bit more affordable. But more importantly, we want to do a step by step video series on how to convert a Mini Cooper Clubman to electric drive, no compromises. It is of little value, if we use components no one can buy anyway.

Jack Rickard
http://evtv.me


----------



## JRP3 (Mar 7, 2008)

ACP seems quite wary of selling to the general public, probably because they don't want to deal with support issues, just sell the product and move on. For $25K a piece you'd think they could afford to talk to you a bit.
The MES-DEA sounds better than I thought it would be, though $12k is still not cheap. What's the torque like on it?


----------



## Guest (Jun 23, 2009)

JRP3 said:


> ACP seems quite wary of selling to the general public, probably because they don't want to deal with support issues, just sell the product and move on. For $25K a piece you'd think they could afford to talk to you a bit.
> The MES-DEA sounds better than I thought it would be, though $12k is still not cheap. What's the torque like on it?


Here's the chart on the motor.
http://www.metricmind.com/images/mes_200-250_starting_torque.jpg

AC Propulsion is hard to talk to initially. They were very nice once we got in contact with them. They claimed the $25k price and 5 unit minimum was so they could provide very good support. The system is very attractive in that the charger and DC-DC converter are built into the 3 phase AC controller. So before sending the check, I wanted to know what was involved in programming the device, and specifically with regards to charging profiles for the batteries. I actually avoid the balancing issues and BMS approaches most of you all are struggling with, but do use some fairly procedural charging profiles with the Brusa charger. And I charge them in a rather specific manner.

The response was that they made a battery module and that we had to use Lithium Ion batteries for it to work. I replied that that wasn't precisely my question HOW do we PROGRAM the charging profiles, assuming this is possible at all. The answer was a little vague. They also have a BMS that apparently you have to install in the car to allow such programming, but the guy was very vague on what it actually did.

In fairness, we were talking to the salesman. The head of the company kept wanting MORE information on what we were doing with it, and I could see that there wasn't enough information in the world for him to be satisfied. And so the conversation was a little too one-way for me. We couldn't really get any technical information on a $125K system, but they wanted to know what we were doing with five of them, when the only reason we were ordering five was because they required it.

I have to tell you, I came away with the impression that the guy who designed it did an incredible job, and the guys who were running the company were a bunch of hesitant, indecisive morons who were deathly afraid of missing their moment in the EV sun. Natural outcome of that in every case I've ever seen, you miss your moment. And I think they will.

If I could buy one at $25 K and it was programmable as the Brusa charger and MES-DEA controller are, I would have done so. I can't. And I can't even find out the capabilities of the device before sending them a check. But if I can't, then the next guy trying to do a Mini Cooper can't either. So why would I go to the trouble to describe how you do this, when you can't get the parts to do it anyway.

I think one of the crippling things in EVland is ALL the marvelous things that are being worked on, but you can't have them yet, or you can't have them at all because we want to sell them to GM. And of course, GM wants to prevent anyone from obtaining any parts but from Mr. Goodwrench, who hasn't paid any of their suppliers in six months.

The Chinese seem to be making products that they want to sell - to any willing buyer with the cash. I just haven't seen a viable AC motor and 3 phase controller from them as yet. A guy on eBay advertised some, and indeed i sent him some money. I never received the device, and had to go through the credit card company to get the money back. He claimed some Chinese source, but I never found out who/what/where.

The three phase controller/ac motor problem isn't that hard. They've used them on appliances for decades. There are several pretty advanced microprocessor chips already done with very advanced algorithms for producing the waveforms. Mostly low powered power sections, but you could couple it to IGBT modules and basically get one working pretty easily. 

But no one has really done it. I would love to see a 150-200kw peak system available from someone where you could easily get spares and support from. There really isn't any reason for the stuff to be $12,000. It would be more expensive than series DC and single channel PWM controllers obviously. 

Yes, I have looked at the Azure Dynamics stuff and no I don't think I'll try one. I saw one poor guy try to sell his, which he'd never installed in anything and it had never been used, and the "Azure babe" jumped in with a totally obnoxious Nazi jackboot message about all they would do to you if you dared buy it, and if you had ANy interest in it, send them lots of cash fast, because they REALLY needed it.

So it's not just that AC is expensive. It's not really available that I can find.
On the upside, the MES-DEA stuff, which is hard to get information on, really does look great.

But I would be much more comfortable with a simple, and widely available GE ac induction motor. And some kind of programmable controller to drive it at 150kw. 

The IDEAL system would indeed combine the charger and controller and DC-DC converter into one package. The charger and controller actually perform very similar functions, very nearly in reverse. But it's a design project quite beyond my skills I fear.

Jack Rickard
http://evtv.me


----------



## Guest (Jun 23, 2009)

JRP3 said:


> ACP seems quite wary of selling to the general public, probably because they don't want to deal with support issues, just sell the product and move on. For $25K a piece you'd think they could afford to talk to you a bit.
> The MES-DEA sounds better than I thought it would be, though $12k is still not cheap. What's the torque like on it?


The chart shows 240 Nm at a little over 300 amps. This is 177 foot pounds. We think we are in an ideal range with this motor. The Mini Cooper Clubman produces exactly 177 foot pounds of torque at 1600 rpm from its ICE engine. Using the BlueSky 100 Ah batteries, we are precisely at 3C at about 300 amps. The controller can produce 400 amps and use voltages up to 400 volts. At 300 amps and 316 volts we should be VERY safely within that envelope. 

So I think these batteries, and this motor/controller, will almost exactly reproduce the power of the original ICE engine in the Clubman, but of course available across a much broader RPM range. 

The result should be a superb match, and better performance from the AC drive train than the ICE, without seriously overpowering the car. I am NOT a fan of putting ever larger engines in a car just because they are available. It may work for NEDRA, but I think it harms the handling characteristics of most cars.

Jack Rickard
http://evtv.me


----------



## david85 (Nov 12, 2007)

Azure is delisting its stock because its so low and the cost to carry it won't even cover the stock value anymore. I don't know what Azure is up to anymore, but I do know that they haven't done anything to upgrade their motors since buying out solectria years ago. I feel their days are numbered unless they are able to get bailout money.

Enova systems is a similar company in the states, but their motors are much better for power to weight ratio and have higher efficiency. Never got any replies from them.

I did try to contact Beth Silverman, and she referred me to CAN EV here in vancouver island, who then never returned my inquiry. Classic treatment that you can expect from most canadian and american suppliers which is why I'm jumping ship and looking off shore for my motor.

I did find a 100kw motor/controller package for $7200USD with the motor weighing about 45Kg and the controller a little under half that. Claimed efficiency was 96% and peak RPM 6000. Only reason I couldn't use it was the operating voltage was 320, and my battery was 144. They were able to set me up with a 144V motor, but had to cut the power way down.

Its a night and day difference trying to do business with an up and coming chinese supplier compared to some one in the western hemisphere. You get the impression, that they are actually happy that you are interested in their product. Some one like ACP and Azure always seem to be giving you the run around. The exception to that rule seems to be Metric Mind, but the prices are prohibitive and technically, Victor is only a distributor not a manufacturer.


----------



## yamez4u (Feb 10, 2009)

Care to give us a link or source? "I did find a 100kw motor/controller package for $7200USD"


----------



## Technologic (Jul 20, 2008)

david85 said:


> Its a night and day difference trying to do business with an up and coming chinese supplier compared to some one in the western hemisphere. You get the impression, that they are actually happy that you are interested in their product. Some one like ACP and Azure always seem to be giving you the run around. The exception to that rule seems to be Metric Mind, but the prices are prohibitive and technically, Victor is only a distributor not a manufacturer.


That's only because ACP wants gov money and doesn't mind going out of business in a few years if those contracts fall through


----------



## JRP3 (Mar 7, 2008)

david85 said:


> Enova systems is a similar company in the states, but their motors are much better for power to weight ratio and have higher efficiency. Never got any replies from them.


I had a similar experience, though after a few months I think I actually did get a reply of some sort. Obviously it didn't leave much of an impression. Wasn't evcomponents going to start carrying Enova systems?



> Its a night and day difference trying to do business with an up and coming chinese supplier compared to some one in the western hemisphere. You get the impression, that they are actually happy that you are interested in their product.


I will say that HPG, hi performance golfcars, was quite helpful and willing to sell their AC31 system, though it's a bit small for most people because of the limitations of the Curtis controller. I do hope they have some luck getting a larger controller built, as well as their larger motor.


----------



## sunworksco (Sep 8, 2008)

What any ev builder has to do is visit ACP's office and pay for the drivetrain and they will help you program the pc.They told me once the build was ready that I could bring it in and they would look it over and make any recommendations for improvements.They get a lot of cheapskates and shade-tree engineers calling constantly and have to qualify each request.I have spoken to everyone there and gotten very good information on the phone,but they are not a DIY center for EVs.This is what this forum is used for.


----------



## david85 (Nov 12, 2007)

JRP3 said:


> I had a similar experience, though after a few months I think I actually did get a reply of some sort. Obviously it didn't leave much of an impression. Wasn't evcomponents going to start carrying Enova systems?


I would be very surprised in that were true since this company prides itself as an OEM. Bottom feeting DIY's like us are not usually good publicity for them. Would be great if they did make their motors more available though.



JRP3 said:


> I will say that HPG, hi performance golfcars, was quite helpful and willing to sell their AC31 system, though it's a bit small for most people because of the limitations of the Curtis controller. I do hope they have some luck getting a larger controller built, as well as their larger motor.


Golf cart motors are not really the same class even if they are getting bigger and more powerful. The motor you picked for your car is probably the best of the best in terms of cost, performance and light weight while still being available. I am still wondering how it would run on higher voltage....


----------



## david85 (Nov 12, 2007)

yamez4u said:


> Care to give us a link or source? "I did find a 100kw motor/controller package for $7200USD"


http://www.tsxdl.cn/eshow.asp?Shop_ID=250


----------



## JRP3 (Mar 7, 2008)

david85 said:


> I would be very surprised in that were true since this company prides itself as an OEM. Bottom feeting DIY's like us are not usually good publicity for them. Would be great if they did make their motors more available though.


You're probably right, as I remember now evcomponents were trying to get a hold of some used Enova systems.




> Golf cart motors are not really the same class even if they are getting bigger and more powerful. The motor you picked for your car is probably the best of the best in terms of cost, performance and light weight while still being available. I am still wondering how it would run on higher voltage....


I think they are trying to pursue the vehicle market and are trying to find higher voltage controllers. The AC31 is an 80lb 9inch motor that can probably take a lot more voltage.


----------



## JRP3 (Mar 7, 2008)

sunworksco said:


> What any ev builder has to do is visit ACP's office and pay for the drivetrain and they will help you program the pc.They told me once the build was ready that I could bring it in and they would look it over and make any recommendations for improvements.


Obviously only practical for people who live near by them. So you have one of their systems?


> I have spoken to everyone there and gotten very good information on the phone,but they are not a DIY center for EVs.


Neither are other companies who seem to have no problem selling their motors to the DIY crowd. Fact is they have turned down a number of serious offers to buy their systems. The only person I know to get one is Jeff from evbones who is using it in an Attack kit car.
http://www.attackforums.com/showthread.php?t=2419
His thoughts on the problems of using cells other than the ones it was designed for:


> The ACP LVMS hardware was designed for use with commodity lithium cobalt chemistry, and does not include a hardware means of balancing individual cell clusters. It relied solely on the residual impedance in the cobalt cells after nearing full to transfer energy to the other series wired clusters. This is not effective with the A123 cells, as the cells impedance rises dramatically when full, and not capable of passing energy to other cells in the series string. They just overvoltage themselves.


On ACP selling to the public:


> Sadly, it has become clearly obvious that AC Propulsion has no interest in supplying their AC-150 systems to the one-off or the do it yourself crowd. Although some believe they can simply order a system from ACP, this is not the case.


----------



## Powered By DC (Jan 3, 2009)

We did get our hands on several Enova 90kw inverters, some are brand new with the protective plasstic covers on them still. We have masters, slaves, dual, and hybrid inverters. We also have 3 of the 18kw chargers and some other misc Enova stuff. I have been in contact with Enjova and they are willing to sell us the motors for these inverters. They have said however that they dont want to offer technical assistance same as every other company. If you are interested in one of these setups email me and we can talk about it.

Dave Kois
EV Components, LLC
http://www.evcomponents.com
253-988-5020
Skype dkoisii


----------



## sunworksco (Sep 8, 2008)

I sent the ACP weblink to the Attack kitcar U.S. importer.Is Jeff the importer?


----------



## JRP3 (Mar 7, 2008)

I don't think so but I don't know for sure.


----------



## Nomad (May 8, 2009)

JRP3 said:


> Or not
> Snipped the pic


GOD DAMN THAT IS SEXY...


----------



## Nomad (May 8, 2009)

david85 said:


> http://www.tsxdl.cn/eshow.asp?Shop_ID=250


Thanks for that link. Did you ever get a motor by motor, controller by controller price quote?


----------



## david85 (Nov 12, 2007)

Nomad said:


> Thanks for that link. Did you ever get a motor by motor, controller by controller price quote?


No, the price was for the combined package. Guessing the controller is close to $5000, and the motor and misc parts are the rest. The 100kw motor weighs 50kg. Also note the constant rated power is 50kw, not too shabby.

I think there was also a 60kw constant, 120kw peak motor but I'm not sure.


----------



## peggus (Feb 18, 2008)

david85 said:


> No, the price was for the combined package. Guessing the controller is close to $5000, and the motor and misc parts are the rest. The 100kw motor weighs 50kg. Also note the constant rated power is 50kw, not too shabby.
> 
> I think there was also a 60kw constant, 120kw peak motor but I'm not sure.



Note that they list stall power as 100kW, this is very strange since shaft power at stall can only be 0W and nothing else. Thus they must be referring to the power going into the motor as being 100kW, which puts the 50kW continuous power into question, is it electrical power or shaft power? 

The efficiency numbers look good but those are no doubt peak numbers.

This is at best a 50kW motor, the starting torque is only slightly better than a ADC/warp 9" motor with a curtis controller.


----------



## david85 (Nov 12, 2007)

peggus said:


> Note that they list stall power as 100kW, this is very strange since shaft power at stall can only be 0W and nothing else. Thus they must be referring to the power going into the motor as being 100kW, which puts the 50kW continuous power into question, is it electrical power or shaft power?
> 
> The efficiency numbers look good but those are no doubt peak numbers.
> 
> This is at best a 50kW motor, the starting torque is only slightly better than a ADC/warp 9" motor with a curtis controller.


Keep in mind this website is originally chinese and translated over to english. Much of the explanations and written content doesn't transfer over very well, indeed if you were to navigate the website and look at the chinese version, there are more motor models listed and more detailed specs. The company is only starting to export this year and are still getting things worked out so don't expect perfection just yet.

Efficiency is always listed as peak, there should be no surprise there. However as a general rule BLDC motors tend to have more consistent efficiency curves that stay in the low 90s most of the time.


----------



## yamez4u (Feb 10, 2009)

Well to be exact the peak 198A X 320v = 63.3KW and 98A X 320v = 31KW continuous, It is basically a direct competitor to the Azured Dynamics AC55. At about the same price point too. The AC90 will give you 100kw peak 414A X 312V=129kw to be exact.


----------



## Coulomb (Apr 22, 2009)

yamez4u said:


> Well to be exact the peak 198A X 320v = 63.3KW and 98A X 320v = 31KW continuous...


Um, are those currents DC current on the input side? I thought the motor current would be per phase, so there would be a factor of sqrt(3) in there somewhere, if the output was a sine wave... but it's trapezoid or almost square or something, so there may be other factors?

Also, these would be electrical power, and motor power is usually quoted in mechanical power output. So presumably 7% or so should be clipped off those figures, if you want "to be exact".


----------



## Guest (Aug 11, 2009)

yamez4u said:


> What did you pay for the "MES-DEA controller and motor from metricmind." what kw is the setup?


I think it was a little over $12,000. The motor was rated for 30kW. This is not only a squishy area, but I have some serious reservations about the ratings game played by AC Propulsion and Tesla. I guess at this point I don't believe the 150 kw or the 185 kw number.

The TIMS 600 controller will do 400 volts and 400 amps max. In theory 160 kW. Both the controller and motor are water cooled Water is about 10x better at conducting heat than air. Both AC Propulsion and TEsla use air to cool the motor and controller. The entire issue of power in an electric motor is about heat dissipation.

A Tesla recently did about 3 laps on a track in a very public fashion and dropped down to about 15 mph to limp back to the pits. Tesla's response was that the drive train was optimized for daily driving and wasn't set up for racing. An odd response for a guy selling a $132,000 sports car. But it's about the cooling system.

We are going to use the Mini Cooper full radiator, a pump that will do about 35 liters per minute, and basically cool both units far beyond what is normally called for. Overkill is always appropriate. I don't intend to race it, but I wouldn't want to have to explain why it wouldn't if someone did.

The bottom line is that power is what simultaneous current and voltage you can put out of the converter, and not blow up the motor. If you have a 150kw system that severely limits itself at 85C (after dumping 85kw) do you really have a 150kw system? Look at both motors? 75 lbs? I am having trouble believing it can do what they say it can do. Sorry.

It doesn't entirely matter. The Tesla is undoubtedly a sexy car and can go fast enough for any reasonable use. How much speeding ticket can you pay for?


Jack Rickard
http://evtv.me


----------



## JRP3 (Mar 7, 2008)

The Tesla may not be able to run at peak output over and over, but it's peak performance numbers seem to support their peak output ratings. Certainly better cooling will help, and I believe Tesla is working on liquid cooling for the future. It's also possible that the Tesla had to "limp" back because the battery pack was heating up and the computer cut back output.


----------



## EVComponents (Apr 20, 2009)

JRP3 said:


> The Tesla may not be able to run at peak output over and over, but it's peak performance numbers seem to support their peak output ratings. Certainly better cooling will help, and I believe Tesla is working on liquid cooling for the future. It's also possible that the Tesla had to "limp" back because the battery pack was heating up and the computer cut back output.


The 2010 Tesla Roadster has extra fans on the motor and PEM. 
We have noticed the difference on my new 2010 Tesla Roadster. Whereas others (previous model year) driving with me were getting overheat warnings (50% torque limited mode) at the track, mine was still operating in normal driving mode.

I am a very "enthusiastic" driver when I am out and about in my Tesla.

See videos for details...

http://peakoilgarage.com/

James


----------



## Bowser330 (Jun 15, 2008)

jrickard said:


> I think it was a little over $12,000. The motor was rated for 30kW....
> 
> The TIMS 600 controller will do 400 volts and 400 amps max. In theory 160 kW....
> 
> ...


Performance graph for the MES-DEA 200-250...

http://www.metricmind.com/images/mes_200-250_efficiency.jpg

On the Inverter page it says that the TIM-600 should peak at 100kw, but it also adds that the TIM900 can peak at 200kw

http://www.metricmind.com/inverter.htm

Prices for MES-DEA components...
But no prices for the TIM-900....hmm..if the TIM600 costs 6K$, could the TIM900 cost 8K$??

http://www.metricmind.com/prices.htm

That would be a 200kw peak setup for about 15K$...


----------



## Guest (Aug 12, 2009)

Bowser330 said:


> Performance graph for the MES-DEA 200-250...
> 
> http://www.metricmind.com/images/mes_200-250_efficiency.jpg
> 
> ...


----------



## Bowser330 (Jun 15, 2008)

jrickard said:


> Bowser330 said:
> 
> 
> > Performance graph for the MES-DEA 200-250...
> ...


----------



## Guest (Aug 13, 2009)

Bowser330 said:


> jrickard said:
> 
> 
> > Ok, very good point...the graphs I posted were at lower voltage and not the max for the inverter....it also doesnt show above 200A, so its very much like the 72V graphs from Netgain...very misleading...my bad..
> ...


----------



## Jan (Oct 5, 2009)

Hi Jack,

Do you still think the mes dea drive has more peak power than listed?


----------



## Guest (Dec 12, 2009)

Jan said:


> Hi Jack,
> 
> Do you still think the mes dea drive has more peak power than listed?


I've seen nothing to change my thinking. But I don't have the drive train in the car yet to do actual current and voltage measurements.

I still think it has more power than the AC Propulsion unit. And I really like the liquid cooling. I'm trying to design a chill plate for the Curtis 1238 at the moment that would let me liquid cool that.

I'm repeatedly finding heat to be the limiting factor on all this. The better you can get rid of it, the better it goes.

Jack Rickard


----------



## Bowser330 (Jun 15, 2008)

I know its been said but maybe you could recover some energy from that waste heat?


----------



## JRP3 (Mar 7, 2008)

Unless your setup is really inefficient there won't be enough heat generated to make it worth the effort.


----------



## Jan (Oct 5, 2009)

jrickard said:


> I've seen nothing to change my thinking. But I don't have the drive train in the car yet to do actual current and voltage measurements.


Thanks Jack.

Found your friday show last night on the net. Man, you talk a lot. I'm not surprised that mes dea isn't installed yet.  

I really love your factory. And the art decco filling station. And the porsche. You have it all.

What I also like about the mes dea is the enclosed design. Looks to me a lot better for automotive applications. 

And fact that it isn't so much more expensive in Europe then comperable DC motors. I just recently found a supplier in Europe. Thought I had to buy it at Metricmind with twice the shipping costs. So, it's on top of my list. 

And if the peak performance is a bit higher, a lot higher, than there is no discussion anymore.


----------

