# LiFePO4 Best Practices for New Cells?



## Tesseract (Sep 27, 2008)

Overlander23 said:


> Ok, so say I've got a whole load of brand new TS LiFePO4 cells fresh off the boat (I don't yet, but will soon).
> 
> What are the best practices at this point?


Good question... The problem here is that they are so new to the EV world there doesn't seem to be any consensus on "best practices". Lead-acid has been around for more than 100 years and people still argue about this sort of stuff!




Overlander23 said:


> Charge them individually (would take forever)?


Ideally, you wire them all in parallel and give them a good, but not complete, charge (to, say, 3.6V). Obviously not terribly practical. 

Another method is to discharge them individually to a consistent and accurate voltage of, say, 3.0V. Now they are all at an equal SoC and when wired in series will have the same endpoint voltage during discharge (jrickard's preference).

And then there is simply wiring them up in series with balancers across each cell and charging until the first one hits high voltage cutoff (HVC). I suppose this is the preference of most other people, though the jury definitely seems to be out.

Personally, I'm not sure which method I like, but as long as the cell-to-cell variation is minimum - under 5Ah for 160Ah cells - then it probably doesn't matter which is used. If there is more variation than that then I would lean towards balancing at the bottom. If their capacities are are all the same then I would lean more towards balancing at the top.




Overlander23 said:


> Test individual cell voltages for consistency and immediately string them in series... and then charge?


Possibly not useful, since you don't know how much charge they were given in the first place... This is why you need to either discharge them individually, or charge them individually, or in series but with balancers, initially to get them "on the same page", so to speak.




Overlander23 said:


> What about securing to the battery posts? Lock washers? Loctite? Noalox?


Ok, my take on this may be somewhat controversial, but here goes... one post on the TS batteries appears to be aluminum while the other appears to be copper or a high Cu bronze, and the supplied bus bars are made of copper, so no matter what there is going to be meeting of dissimilar metals and so you should apply NoAlOx grease to the joint.

That said, you have to keep in mind that NoAlOx is mostly grease and therefore mostly an insulator. It has to be thoroughly squeezed out of a joint for good electrical contact to be made (it provides protection by leaving behind zinc particles while the exuded grease prevents oxygen from getting into the joint). This is all well and good when you are filling a crimp lug with the stuff then crimping the crap out of it with a hydraulic press, etc., but from a strictly intuitive perspective I am skeptical that you can generate enough clamping force on the TS cell's terminals - especially the aluminum ones - to force the grease out well enough to allow good contact. On the other hand, you need to use it because there is contact between copper and aluminum, and that is about as bad as you can get for galvanic corrosion to occur. The lesser of two evils is to apply NoAlOx, definitely.

Finally, I am partial to the use of either Belleville washers, or internal tooth lockwashers, to actually lock the bolts, and not split-ring. Split ring is better in high-torque applications; the latter two types of lockwasher are better when clamping to a soft material, like a aluminum. Obviously, you also need to choose stainless steel or bronze hardware here.




Overlander23 said:


> How do you break in a new set of LiFePO4s without specialized equipment... if its possible?


Short answer: you can't.


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## JRP3 (Mar 7, 2008)

The cells should come with stainless bolts, flat washers, and split washers. I'd suggest you make sure you get noalox on the threads as well or you might get galling between the stainless bolt and aluminum thread.


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## DIYguy (Sep 18, 2008)

Tesseract said:


> Finally, I am partial to the use of either Belleville .........Obviously, you also need to choose stainless steel or bronze hardware here.


Yes! I'm a fan of SS Belleville washers for this application... and SS screws.... there are a few reasons... but will leave it at that.


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## etischer (Jun 16, 2008)

You might clean up the aluminum lugs and copper busbars with a scotch bright pad or steel wool to get a clean surface before applying Noalox. 

-edit- steel wool is probably a bad idea now that I think about it, could leave conductive strands of dust behind to fry BMS boards


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## JRP3 (Mar 7, 2008)

I was thinking it might be important to get between the layers and polish them as well since the connectors are 5 strips of copper piled together. I wonder if there is something you could dip them in to clean them?


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## tomofreno (Mar 3, 2009)

> I'd suggest you make sure you get noalox on the threads as well or you might get galling between the stainless bolt and aluminum thread.


 Stainless fasteners are used with aluminum to avoid galling (doesn't react with the aluminum). I don't think the grease is necessary, and may contribute to loosening of the fasteners over time. It seems only a very thin coating of noalox is necessary on the terminals, as that is all that is required to prevent oxygen diffusion to the surface, and it is an insulator. I just smeared a little into a clean rag and wiped the terminal and straps with it. The instructions on the bottle say to sand it into the conductor surface. I didn't like leaving a mix of sanded particles/goop on the surface to reduce contact area, so I sanded with 600 grit carborundom, wiped thoroughly with a clean dry rag, wiped with noalox wetted rag, and bolted.

Tom


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## JRP3 (Mar 7, 2008)

As a lifelong boater I'm going to have to disagree a bit. I've dealt with too many stainless steel fasteners frozen in aluminum. Galling is a bit different than straight corrosion. I think galling results from the physical interference of the two surfaces locking together, possibly when the surfaces are scraped during assembly. Since they are also dissimilar metals there is also the possibility of corrosion.


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## dimitri (May 16, 2008)

TS cells come with decent SS bolts, OK quality lock washers ( although I tend to agree with Tesseract that different type of locking would be better ) , but really crappy flat washers ( too thin and too small diameter to cover post area and create good pressure area between the link and the post). I would recommend at the minimum to get thicker and larger flat washers and use max safe torque when bolting it all down.

In my pack I already learned a lesson from not fully torqued bolt, it gets pretty warm after 3C discharge and easy to spot and fix.

I also used Noalox and it squeezes out pretty good, so using just a little should be sufficient.

I also recommend a good but not abrasive cleaning of each post since they get quite dirty and oxydized after being on a ship and in storage for a while.

Also, a good test is to measure voltage between terminal post and the other end of the copper link while charging at CC phase, if you find a few millivolts difference on some cells compared to others, you may have a dirty or loose connection.

Hope this helps.


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## dimitri (May 16, 2008)

OK, I finally got off my butt and measured the torque on my terminal bolts. Its 18 ft/lb , just like someone here suggested for this size of bolts.

When I first assembled my pack I was stupid enough to just use impact wrench, thinking it was sufficient, but when I found one bolt heating up on me I checked all of them by hand and found that many weren't tight enough. Now they are all 18 ft/lb and none get warm at all 

Hope this helps.

BTW, Thundersky manual just states to have bolts tight, but does not mention specific torque.


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## Overlander23 (Jun 15, 2009)

Going to order a bunch of Belleville washers... I'm pretty sure the TS160 cells have a 5/16" bolt diameter. Can anyone tell me the diameter of the mounting post (for the outside diameter of the washer)?


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## JRP3 (Mar 7, 2008)

Here's an interesting article on force vs torque, lubrication, and using belleville washers in electrical connections:
http://www.maintenanceworld.com/Articles/shackmann/thetrouble.html
another one:
http://ecmweb.com/mag/electric_belleville_washers_correctly/


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## Tesseract (Sep 27, 2008)

Good finds, JRP3...

Couple especially salient points from that first article... the author found that the (presumably recommended) torque values for SAE Grade 5 hardware producing good electrical connections. You can't torque aluminum threads to SAE Grade 5 standards, so...

Belleville washers to the rescue! Able to achieve as consistent a torque value/electrical resistance as using a direct torque indicator (presumably a torque wrench).

From the second article I'll just quote:



> Most often, you'll find Belleville washers in applications where you have to connect bare, soft aluminum to aluminum or copper, or where you have conditions of high current loading or cycling. These washers do wonders for accommodating thermal cycling, but they can't eliminate all the problems resulting from poor workmanship. You must prepare the joint properly (as with any connection), but the key is selecting the proper design and size of Belleville washer for the fasteners and conditions of your application.


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## tomofreno (Mar 3, 2009)

> I'm pretty sure the TS160 cells have a 5/16" bolt diameter. Can anyone tell me the diameter of the mounting post (for the outside diameter of the washer)?


 Yes, 5/16. 3/4".


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## dimitri (May 16, 2008)

Overlander23 said:


> Going to order a bunch of Belleville washers... I'm pretty sure the TS160 cells have a 5/16" bolt diameter. Can anyone tell me the diameter of the mounting post (for the outside diameter of the washer)?


Copper link is 22 mm wide and part of the post which makes contact is 20 mm diameter, so I would get a washer about 20 mm in outside diameter.

This is on my TS160 cells.....


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## tomofreno (Mar 3, 2009)

Thanks JRP3. So what force bellvilles are required for 15 lb-ft torque in aluminum? And if you lubricate the bolt threads does that make it more likely to loosen over time with thermal cycling?


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## tomofreno (Mar 3, 2009)

> So what force bellvilles are required for 15 lb-ft torque in aluminum?


 Answer is at the link below and the tables in the accompanying pdf:

http://www.torqueleader.com/general.asp?id=3#

Grainger has appropriate belleville for around $0.75 ea, and 1/8" thick ss washers with 3/4" O.D. for a little over $1.00 ea. So around $70.00 for 36 of each. Think its worth it JRP3?


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## JRP3 (Mar 7, 2008)

You already know the answer  Are people using the split washers properly torqued seeing problems? As Jack would say no reason to solve a problem that doesn't exist.


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## hardym (Apr 2, 2008)

On the initial topic:
TS cells come about half charged, but with a wide variation. According to a careful read of the manual, they need to be fully charged to 4.2 and held there for a while to be 'formatted' Suggest individual cell charging on a bench power supply.

Most balancing schemes will never be able to balance with the wide variation in initial charge.

Mark.


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## dimitri (May 16, 2008)

hardym said:


> According to a careful read of the manual, they need to be fully charged to 4.2 and held there for a while to be 'formatted'


Mark,

we discussed this some time ago, I went thru every line of TS manual and never found evidence for "formatting". I believe its just a poor translation from Chinese. Do you have any data supporting this theory?

Cells are fully charged and then test discharged at the factory, so if any "formatting" is needed it would be done there.


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## tomofreno (Mar 3, 2009)

> Most balancing schemes will never be able to balance with the wide variation in initial charge.


 My SE cells were all charged to 3.27 to 3.28V when I received them. The range is likely less than 0.01 due to rounding of my two decimal place dvm, so less than 0.3% range. My experience is that you will have to play around charging individual cells with a 3 -5A charger for 10 minutes or so at a time to get them closer than this, and it isn't of much value due to the small Ah difference.


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## JRP3 (Mar 7, 2008)

I agree with Dimitri and Tom. My SE cells came charged between 3.25 and 3.26.


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## Overlander23 (Jun 15, 2009)

What's the theory behind cells connected in parallel in regards to differing voltages? I know that voltage across the pack will equalize, but how fast will it do this? I'm guessing it has something to do with each cell's internal resistance?

I've got this idea of having the BMS system basically open the cells up to each other in parallel (through the BMS) to equalize voltages at, say, the LVC knee. No shunting required and a possible way of bottom balancing. If the process takes a long time, this would be done a little bit before every charge cycle... slowly equalizing the cells over time.

Possible?


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## 86Honda (Apr 15, 2009)

When I installed a new cell in the pack, the voltages did not match exactly, with the new cell being lower by about .2 V. It took two charge cycles and several days for it to balance enough to shunt at the same time as other cells.


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## Overlander23 (Jun 15, 2009)

But that's keeping the pack in series and equalizing via shunt charging, correct? 

My idea is to use the BMS to create a parallel pack when the pack is not under load (being used) or being charged... more or less. 

I'm one who believes that taking a pack to series LVC is a bad idea unless the LVC is pretty high. It seems all current BMS strategies are designed to protect the pack from the people. Don't come close over-discharging and over-charging and the pack should be fine... but if there were such a phenomenon as SOC drift between the cells of a series pack (not to be confused with IR and capacity differences), then a parallel equalization technique could be a pretty passive way of managing it.




86Honda said:


> When I installed a new cell in the pack, the voltages did not match exactly, with the new cell being lower by about .2 V. It took two charge cycles and several days for it to balance enough to shunt at the same time as other cells.


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## racunniff (Jan 14, 2009)

Overlander23 said:


> My idea is to use the BMS to create a parallel pack when the pack is not under load (being used) or being charged... more or less.


I've considered this, but you need lots of high-amperage relays/contactors - at least one per cell == $$$$$ - how do you plan to avoid this?

Also, where do you find a low-voltage charger that can put out the amps you would need to charge your very deep parallel pack in a reasonable amount of time? Build your own?


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## Overlander23 (Jun 15, 2009)

You'd still charge in series with a conventional charger. The only purpose of the BMS allowing the cells to connect in parallel would be to equalize their voltages when the pack is at rest. That would be small amounts of current, something the BMS wiring could handle with small relays or transistors.

IMO, if a cell drifts so far away from others in a pack that it would require significant amounts of energy exchange then it needs to be replaced. No amount of balancing will help it.

Keep in mind that this procedure is purely to line up all the cells' SOC at a particular level in a passively automatic way. It serves the same kind of purpose as shunt bleeding at the top of a charge, except could happen at the bottom of a charge where it's, arguably, more useful.

You could conceivably pick any voltage to equalize depending on when you decide to have the BMS go parallel.

Once the cells have been sitting in parallel for a bit, the BMS switches back to cell monitoring and the charger charges conventionally until the BMS senses the first cell to hit HVC which shuts the charger down.

The cells will all have differing amounts of power in them, but as the pack draws down under normal use the cells will all hit their equalization voltage at the same time... at the bottom of the pack, assuming that's where the BMS did the "equalization" stage.


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## dimitri (May 16, 2008)

Overlander23 said:


> That would be small amounts of current, something the BMS wiring could handle with small relays or transistors.


No, it would not work as you describe. You still need to interrupt serial connectors, which carry full load when driving, so you can't do that with small relays. Also, when you connect cells in parallel, there will be maximum current rush trying to equalize the voltage across all cells, this current will be significant and difficult to measure, but most likely to burn small relays.

Your idea, while a good theory, is unfortunately not practical in real life. You will need bunch of large contactors to switch from serial to parallel config and it will cost more than any reasonable BMS and likely be close to the cost of the battery itself.


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## Overlander23 (Jun 15, 2009)

Ackk... I forgot about the serial connection... oddly. Yeah, that would be a short circuit if used with parallel wiring. Nevermind. Oops. 



dimitri said:


> No, it would not work as you describe. You still need to interrupt serial connectors, which carry full load when driving, so you can't do that with small relays. Also, when you connect cells in parallel, there will be maximum current rush trying to equalize the voltage across all cells, this current will be significant and difficult to measure, but most likely to burn small relays.


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## Overlander23 (Jun 15, 2009)

I'm rehashing an old thread because I'm finally back in a position where I have to do something about finally building my traction pack.

So, "best practices" for build a traction pack from new LiFePO4 cells...

Of the methods mentioned in previous threads I'm leaning toward either stringing all the cells in parallel and charging to 3.6v... or charging each cell individually. 

I have time, so the former isn't necessarily impractical, and they're all sitting on the floor currently. But I have a question with the latter method.

If all my cells are currently reporting ~3.31 volts (with a cheap DVM that only reads to two decimal places) does that mean they're all at the same state of charge? I ask because of LiFePO4's flat discharge curve.

If I manually charge each cell to 3.4 (or 3.5, 3.6, pick a voltage) volts (as registered on a DVM), for instance, would they be theoretically balanced regarding capacity?

It looks like I'll need some tools to do this. I've got my EV's charger, but that's obviously set up for the whole pack.

I've also got a couple of RC LiPo chargers (an Orbit Microlader and an E-Flite charger) but these are designed for airplane packs. The Orbit, for instance, charges to 4.2v, non-adjustable. Methinks too high to finish a TS160. But I suppose it would work to put juice in until the cell reaches a manually monitored 3.6v. I can control the max output current.

Or I could get a bench power supply. Any ideas on a something reasonably priced?

Any other suggestions?


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## dimitri (May 16, 2008)

Overlander23 said:


> If all my cells are currently reporting ~3.31 volts (with a cheap DVM that only reads to two decimal places) does that mean they're all at the same state of charge? I ask because of LiFePO4's flat discharge curve.
> 
> If I manually charge each cell to 3.4 (or 3.5, 3.6, pick a voltage) volts (as registered on a DVM), for instance, would they be theoretically balanced regarding capacity?
> 
> ...


Search Ebay for "mastech power supply", plenty of choices, different prices. Don't get anything less than 3Amp though, it would take forever to charge your cells.

Your LiPo chargers can be used, but you have to watch the voltage like a hawk and not let it climb over 3.8V-4.0V.

Don't charge less than 3.5V since anything below 3.5V for TS cells is still in the flat area and not a good indication of SOC during charging. I would recommend to go to 3.8V to make sure all cells are lined up at the top.

Of course it will drop to 3.4V after a few hours, but knowing that each cell was at 3.8V at the end of charge ensures good top balance.

If all cells came from same manufacturing date ( you can tell by serial numbers, it has the production date encoded in the number DDMMYY or something like that ) and report same voltage, chances are they are in pretty good balance.

Hope this helps


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## JRP3 (Mar 7, 2008)

Depends. Are you going to use a BMS? Are you going to top balance? Have you considered bottom balancing? If they are all showing 3.31V they are probably pretty close but you won't really know till you hit the bottom or top of the curve.


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## Overlander23 (Jun 15, 2009)

Would it matter much if it was a switching vs linear power supply? I don't imagine it would for this purpose.

Further info. Still on the fence about a BMS. No one has built a commercial version that has the features I'd like, yet... or for a reasonable price (maybe it can't be done for a reasonable price).

For the time being, my Elcon is set to 3.75v and given my usage, I won't be going more than 50% SOC.

What I'd like is very close to what Dimitri has, just with the ability to monitor the individual cell voltages... cuz I'm a nerd like that. Trying to figure out whether a linked group of PIC/AVR MCUs (each handling a group of cells) would work... and then let a master processor handle LVC or HVC signaling and info display/logging. Maybe even add charge shuttling/balancing at some point since the hardware will be there.


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## JRP3 (Mar 7, 2008)

A lot of work for little to no benefit. Once upon a time I thought I'd care about individual cell voltages, but they don't matter much in the day to day operation of the vehicle if you stay within a reasonable range of your pack limits, which is a good idea anyway for long life.


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## Guest (Aug 21, 2010)

You can always build a multi voltage terminal to connect single power lines to each cell and have ground common. Keep it covered and when you want to check single cells just open the cover and check each connection for single or multiple for larger chunk checks. Have each marked for each battery and that way you don't have to go digging around in the car to check a specific battery. If you find one going south you will know where in the pack that battery is and you can go take it out and replace it. Checking each cell is not something you will do very often. Why bother to have an expensive to check that. Once per month or every few months maybe. After you figure out your not gaining anything then you just check maybe a couple times per year. You can check daily if you like but why?


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## dimitri (May 16, 2008)

JRP3 said:


> A lot of work for little to no benefit. Once upon a time I thought I'd care about individual cell voltages, but they don't matter much in the day to day operation of the vehicle if you stay within a reasonable range of your pack limits, which is a good idea anyway for long life.


I think this is very common with LFP users. Everyone comes into it with desire to baby sit them since they are so damn expensive, then after a while you care less and less about cell voltage, and eventually you even stop caring about pack voltage, as long as cells are in the healthy operating range of course. Where exactly within that range they are at any given time, I don't care at all. All I need is to know the cells are in OK state and AH meter showing SOC, the rest is pretty useless info.


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## dimitri (May 16, 2008)

Overlander23 said:


> Would it matter much if it was a switching vs linear power supply? I don't imagine it would for this purpose.


Absolutely not. These cells will suck every living electron from any supply and ask for more. Don't matter how you feed it.


> Further info. Still on the fence about a BMS. No one has built a commercial version that has the features I'd like, yet... or for a reasonable price (maybe it can't be done for a reasonable price).
> 
> For the time being, my Elcon is set to 3.75v and given my usage, I won't be going more than 50% SOC.
> 
> What I'd like is very close to what Dimitri has, just with the ability to monitor the individual cell voltages... cuz I'm a nerd like that. Trying to figure out whether a linked group of PIC/AVR MCUs (each handling a group of cells) would work... and then let a master processor handle LVC or HVC signaling and info display/logging. Maybe even add charge shuttling/balancing at some point since the hardware will be there.


Guys at Australian EV forum have been developing a BMS like that. Its been a while since I looked at that thread after certain someone crapped all over it. Here is the link 

My biggest concern with digital BMSs sending data over serial links is EMI resistance. BMS has to be reliable before anything else.


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## Overlander23 (Jun 15, 2009)

What I've ended up doing is wiring all 64 of my TS160 cells in parallel. I purchased a Mastech HY1520EX (which will do 20 amps at up to 15V) and am currently using constant voltage at 3.7v to charge all the cells. But the setup is maxing out at around 7.5 amps, and I know that I do more.

So, I understand the CC/CV concept. While the cells are all about 1/2 charged (I'm guessing) at 3.31v, I imagine I can pump the full 20 amps the PS is capable of into the cells... until I get to, say, 3.5 or 3.6v, but to do this, the charge voltage needs to go up.

Is there a limit to how much voltage I can pump into the cells during the CC phase? 

Should I just run the voltage high enough to hit 20 amps, and monitor the cells until they hit 3.5v... and then finish off with CV at 3.7v or 3.8?


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## Overlander23 (Jun 15, 2009)

Looks like the Mastech won't output a constant 20 amps at a voltage setting of 4.2v or under. The supply just goes into CV mode. I'm thinking I shouldn't go above 4.2v, since this is what Thundersky indicate the maximum charge voltage is for LFP cells.

At 4.2v the Mastech is outputting 15 amps in CV mode. Getting the supply to go into CC mode would require increasing the voltage level. Then again, these Mastech's are a bit confusing. Anyone with any Mastech experience?

This is gonna take awhile...


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## JRP3 (Mar 7, 2008)

You've basically got a 10,000 + ah battery with all those cells in parallel so yeah it's going to take a while. You can set the voltage as high as you want as long as you turn it down before the cells get near full. Crank it up while you're around to monitor it and turn it down to 4.0 to be safe when you're away. TS new top voltage is 4.0 by the way.


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## Overlander23 (Jun 15, 2009)

Indeed... If the cells are half full, that's at least 11 days of charging at the full 20 amps. 

Maybe it makes more sense to wire them all in series, use my Elcon to get 85-90% of the way there (while monitoring cells, of course)... and then re-wire in parallel to finish it off.



JRP3 said:


> You've basically got a 10,000 + ah battery with all those cells in parallel so yeah it's going to take a while.


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## JRP3 (Mar 7, 2008)

Yes that makes more sense.


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## dimitri (May 16, 2008)

Overlander23 said:


> Looks like the Mastech won't output a constant 20 amps at a voltage setting of 4.2v or under. The supply just goes into CV mode. I'm thinking I shouldn't go above 4.2v, since this is what Thundersky indicate the maximum charge voltage is for LFP cells.
> 
> At 4.2v the Mastech is outputting 15 amps in CV mode. Getting the supply to go into CC mode would require increasing the voltage level. Then again, these Mastech's are a bit confusing. Anyone with any Mastech experience?
> 
> This is gonna take awhile...


Voltage should be the same as the battery, no matter how much you crank the supply, until it reaches full current. If your supply voltage goes higher than battery voltage, then your wires from supply to the battery are too thin and develop a voltage drop, get thicker wires, better connections.

You should set your supply to 4.2V at open circuit, current set to max, then connect to the battery. At that point supply voltage will drop to the battery voltage ( if wires are good ) and it will pump as much as it can.

Since you set 4.2V open voltage, you don't have to worry about overcharge, although in your case it would take sooooo long that you can't miss it. Even the upper knee when it goes from 3.4V to 3.7V will take hours probably.

BTW, they are not half charged from the factory, they are often 70%-80% charged, all depends on how long they were on the shelf after they left the factory.


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## F16bmathis (Jun 6, 2008)

Can I have a long answer? I'm purchasing TS160's and need to know what to do. My Manzanita will go as low as 12V, so I could wire the batts as 24 12V's, and I do have a small power supply, I think it'll go lower than 12V... gotta check.

Its amazing how low TS dealers will go when they find yo are buying from someone else. I've had offers from $10,000 (get them in 2-3 days) to as low as $8300, some with terminals and hardware, some without, and some with a month and a half wait.


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## JRP3 (Mar 7, 2008)

What are you looking to do, top or bottom balance, with or without BMS? If top balancing you should wire them in series and monitor them as they charge since the Manzanita will need to be adjusted. Once they start to climb in voltage you'll have to do something to bleed off charge or add charge to individual cells.
Where are you getting your cells from and at what price?


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## F16bmathis (Jun 6, 2008)

I guess top balance, but I just read about that here. BMS will most likely be from Hipower. Has a touchscreen display shows amps, voltage, individual batt voltages and such. Looks good. Other choise may just be the Mini BMS, but I cant seem to figure out exactly what is needed- 45 boards, then one main board, or... But then I've got to keep my analog meters.

My power supply only goes down to 12V. Same with the Manzanita. I have one 160ah TS to play with.

188.8 Ea ($8460)from Hipower (energetech.com) with all hardware in 6-8 weeks, then add shipping or $208 Ea ($9360)from Elite Power solutions with all hardware immediately, free shipping... Have not decided yet. With all I need to do to get the lead acids out, then I'm understanding I have to make really good battery boxes for the TS's, might take some time anyways.

The boxes will be made of aluminum (I have alum welding capability, and I'm actually getting good at it), but I cant seem to make anything without having the exact dimensions, basically weld around the actual batteries - no I won't really do that and weld the batteries!, just use the actual batts as form, remove them and weld. Aluminum boxes is O.K.? Have not heard of anything negative about them.


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## dtbaker (Jan 5, 2008)

F16bmathis said:


> 188.8 Ea ($8460)from Hipower (energetech.com) with all hardware in 6-8 weeks, then add shipping or $208 Ea ($9360)from Elite Power solutions with all hardware immediately, free shipping...


EvolveElectrics.com has TS in stock in the US right now, and I just took delivery of a set, so can vouch for delivery.



F16bmathis said:


> The boxes will be made of aluminum ...Aluminum boxes is O.K.? Have not heard of anything negative about them.


I went with welded plastic (polypro can be heat-welded) to reduce thermal issues in the winter, and to eliminate possible zapping from accidentally grounded HV cables/terminal. I made outside skeleton from 1x1 steel, and lined w/ 1/4 polypro, then welded the inside corners to stiffen and keep battery acid off steel. The polypro is pretty easy to work with.... check the battery rack construction section and gallery on my website if you want.


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## F16bmathis (Jun 6, 2008)

How did you pay? They want me to wire transfer the cash, but I'm more of a Pay-Pal safety net kind of guy.

I thought ThunderSky's had to be incased tightly to stop expansion. I'll go check you battery box.


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## dtbaker (Jan 5, 2008)

F16bmathis said:


> How did you pay? They want me to wire transfer the cash, but I'm more of a Pay-Pal safety net kind of guy.


EVolveElectrics.com can take credit cards, but tack on the 3.9% if you do. After lengthy discussions and threats of siccing my wife on him if he screwed me like James Morrison ( EVComponents/LithiumDepot) did, I decided to send a personal check. Made me very nervous, but transaction happened on time and he did not cash check until the day the batteries shipped.



F16bmathis said:


> I thought ThunderSky's had to be incased tightly to stop expansion. I'll go check you battery box.


they *should* have endplates to prevent swelling... I plan to either strap chunks of cells together, or fabricate 'blocks' to fit the batteries tightly in the middle of the space. My racks were designed for 8v floodies, so I will have to modify to rack the TS. My comment against AL is just that in the winter it would suck heat out of the batteries and hurt performance significantly; and present a 'possible' path for grounding that you might want to avoid.

check my gallery around this area:
http://www.envirokarma.org/ev/gallery/090125_rrack02.foam.htm
or the thumbnails here:
http://www.envirokarma.org/ev/gallery/index5.htm


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## JRP3 (Mar 7, 2008)

F16bmathis said:


> I guess top balance, but I just read about that here. BMS will most likely be from Hipower. Has a touchscreen display shows amps, voltage, individual batt voltages and such. Looks good. Other choise may just be the Mini BMS, but I cant seem to figure out exactly what is needed- 45 boards, then one main board, or... But then I've got to keep my analog meters.


One board for each cell and then one head unit for the entire pack.



> The boxes will be made of aluminum (I have alum welding capability, and I'm actually getting good at it), but I cant seem to make anything without having the exact dimensions, basically weld around the actual batteries - no I won't really do that and weld the batteries!, just use the actual batts as form, remove them and weld. Aluminum boxes is O.K.? Have not heard of anything negative about them.


You'd probably want to wrap insulation around them for the winter.


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## Russco (Dec 23, 2008)

dtbaker said:


> EvolveElectrics.com has TS in stock in the US right now, and I just took delivery of a set, so can vouch for delivery.


Did your Thundersky batteries ship from Burlingame, California? Were the date codes all the same? Were they strapped together in bundles for your application?


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## dtbaker (Jan 5, 2008)

Russco said:


> Did your Thundersky batteries ship from Burlingame, California? Were the date codes all the same? Were they strapped together in bundles for your application?


EvolveElectrics.com retails for http://www.alliancerenewableenergy.com who prefer to wholesale and sell large lots and NOT take credit cards. I decided I'd rather buy thru EVolve, paid the same $1.30/ah but wanted the margin to go to the little guy.

batteries are UN strapped, and bus bars are $4.50 each.


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## F16bmathis (Jun 6, 2008)

I haven't ordered them yet. In a day or three, but by friday...


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## F16bmathis (Jun 6, 2008)

JRP3 said:


> One board for each cell and then one head unit for the entire pack.
> 
> 
> You'd probably want to wrap insulation around them for the winter.


Thanks for the info, I'll insulate, and consider the mini bms


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## F16bmathis (Jun 6, 2008)

dtbaker said:


> EvolveElectrics.com retails for http://www.alliancerenewableenergy.com who prefer to wholesale and sell large lots and NOT take credit cards. I decided I'd rather buy thru EVolve, paid the same $1.30/ah but wanted the margin to go to the little guy.
> 
> batteries are UN strapped, and bus bars are $4.50 each.


Evolve has a good price, but charges for shipping, straps are extra at $4.50 ea and does not have any in stock at this time. 
Elite Power Solutions is slightly more expensive, has them in stock, has all the jumpers, bolts and washers with them, and does not charge for shipping, so overall a better price I think. Not sure about straps.


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## dtbaker (Jan 5, 2008)

F16bmathis said:


> Evolve has a good price, but charges for shipping, straps are extra at $4.50 ea and does not have any in stock at this time.
> Elite Power Solutions is slightly more expensive, has them in stock, has all the jumpers, bolts and washers with them, and does not charge for shipping, so overall a better price I think. Not sure about straps.


wow, so EVolveElectrics sold their whole shipment in two weeks.... Alliance might still have some, but you have to pay by check. Before buying from Elite or anyone else, I would post to this group to see if anyone has taken delivery from them recently, and ask where their batteries come from; you really want to make sure they are not getting them from James (EVComponents/LithiumDepot).

no matter who you buy from, consider posting followup on your experience here so other buyers can get a feel for the Vendors....


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## Overlander23 (Jun 15, 2009)

Back to the topic of cell voltages...

I've done a couple of things. I measured all my brand new cells, as they came from the factory, at rest and found that all 64 were pretty much reading 3.31 volts.

I strung them all together in parallel, realized it would take a ridiculously long period of time to charge a 10240 AH pack at 3.8 volts... so I restrung with buss bars as a series pack so that I can use my Elcon (algorithm is set to a 3.6v knee and a 3.8v finish, I may get this changed).

While monitoring cells (with the Elcon in CC mode) I start noticing, after awhile, that certain cell voltages are rising faster than others. Not terribly surprising.

When the highest cell went to 3.8, I disconnected the charger. All the other cells were reading about 3.5, at the time. I pulled the cell out of the loop and continued to charge until the next highest cell went to 3.8.

At this point I shut everything down and started to charge blocks of four cells in series with my 15v/20A Mastech supply. Again, certain cells would pop forward to 3.8 faster than others.

I'm sort of at the beginning of this part. Now the individual cells of the four-cell blocks get hit to 3.8 in CV mode.

Question is, at what current are things "close enough". In other words, it will take forever to actually get the cell to 3.8v under CV as the current keeps lowering to nothing. If I've got the Mastech set 3.8v, would it be reasonable to stop when the current drops to C/20,40,60,80,160??? Keep in mind, these are TS160s.

As an example, I've got an individual cell set to 3.8v in CV mode that is reading 3.577v at the cell terminal while drawing 4.2 amps. Its voltage is slowly increasing and the current is slowly decreasing.

I'm going for consistency here... I'll keep an eye on the characteristics of another cell. Maybe I should just cut off the process when each cell reaches the same voltage and current draw. Say, 3.6v @3.1A 

Now that take a closer look at my Elcon's charging curve (algorithm 310), it looks like the final CV stage, right to 3.8V is at C/100. So that would be 1.6A. Hmmm...


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## glaurung (Nov 11, 2009)

I tried to charge my 68x200 pack in series, but noticed same thing.
It took six days of charging them to 4.1v parallel, but now it is done.I will now drive a few times and then bottom balance all, i should be ready for safe driving after that.
Harri


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## dimitri (May 16, 2008)

You can consider any cell that has passed the knee ( 3.6V-3.8V ) as full, regardless of the current ( this is true with currents under 0.5C ).

You are doing it the right way and you are discovering that SOC is all over the map, which is perfectly normal for new cells.

As long as you are watching closely and setting aside all cells that have reached 3.8V, you will end up with all top balanced cells when you are done. 

The current only determines how long the process will take. The more current the better, but you must watch the voltage like a hawk if you push more current into a group of cells, because one of them will likely shoot up before others.

This is why its much easier to do with BMS modules installed, since you have the visual on all cells at once and don't run around with DMV like crazy


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## dtbaker (Jan 5, 2008)

dimitri said:


> This is why its much easier to do with BMS modules installed, since you have the visual on all cells at once and don't run around with DMV like crazy


or wire in parallel, set to 3.7v, and just let it take however many days until it drops down to an amp....


d


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## JRP3 (Mar 7, 2008)

glaurung said:


> I tried to charge my 68x200 pack in series, but noticed same thing.
> It took six days of charging them to 4.1v parallel, but now it is done.I will now drive a few times and then bottom balance all, i should be ready for safe driving after that.
> Harri


Why would you go to all the effort of top balancing the pack and then reverse all that work by bottom balancing?


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## glaurung (Nov 11, 2009)

According to GWL-Power cells are supposed to be charged to 4.2 before first use. I adjusted my charger and meter showed 4.1something and i used that.
Only trouble was putting cells to two rows on table and bolting them together.Somehow bottom balancing appeals to me.


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## dtbaker (Jan 5, 2008)

I don't think I would take'm up to 4.1 either.... 3.7 maybe.


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## dtbaker (Jan 5, 2008)

glaurung said:


> Somehow bottom balancing appeals to me.


so.... how do you catch them at the top of the charge cycle? Does your BMS shut down your charger when the FIRST cell hits your high-voltage trigger?


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## JRP3 (Mar 7, 2008)

glaurung said:


> According to GWL-Power cells are supposed to be charged to 4.2 before first use.


I think they are mistaken. As I've pointed out many times, cells are fully charged and discharged at the factory during testing to check capacity. Since they've already been taken to their cutoff voltage at the factory, what is to be gained by doing so again?


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## dtbaker (Jan 5, 2008)

JRP3 said:


> Since they've already been taken to their cutoff voltage at the factory, what is to be gained by doing so again?


I totally agree... seems best to balance at where you expect you charger to shut'em off; which is probably 3.65, or maybe 3.7 ?


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## JRP3 (Mar 7, 2008)

If he's bottom balancing then there is no point in top balancing at all.


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## honn1002 (Nov 26, 2008)

JRP3 said:


> If he's bottom balancing then there is no point in top balancing at all.


I didn't perform any balancing when I received my batteries. One of the cells had a little low voltage reading, so I charged it up to match with the rest before I charged the whole pack. So far I've put over one thousand miles on the batteries. 

I use celllogs to monitor and control low and high voltages. Initially I set my cells HVC at 3.6V to turn off the charger. Lately I set the cells HVC at 3.5V and after finished charging as the charger is automatically shut off, I found out that I still get all the amps used back to the pack. For example my pack capacitor is 180Ah. I used 120Ah, I have 60Ah left on the pack. When I recharge over night, in the morning the charger is off and the EV display shows 180Ah at max capacity. I keep my cells HVC at 3.5V seems to work fine so far.


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## glaurung (Nov 11, 2009)

It is advised to do the first charge as instructed and after that only to 3.7-4.0
http://gwl-power.tumblr.com/post/576978080/faq-initial-charging-information-the-above-is
Looks like a manufacturer instruction label to me.


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## JRP3 (Mar 7, 2008)

Thundersky has already lowered their max voltage to 4.0V. Additionally since the cells were already full charged at the factory what is the point of doing it again, when we know avoiding a full charge is better for the cells?


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