# Is Lithium Going Downhill



## Russco (Dec 23, 2008)

With the recent low temperatures in Florida, Dimitri has found some out-of-whack Llthium cells. And Brian (of Volt Blocher fame) from California has also experienced bad lithium cells. Now Brian has his red Honda EV for sale in "The Trading Post." 

Is lithium not all it's meant to be? 

Makes me sorta glad I've stuck with old fashioned flooded lead acid.


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## Tesseract (Sep 27, 2008)

Russco said:


> ...
> Is lithium not all it's meant to be?


Dunno... Are tools from Harbor Freight all they are meant to be? (That is to say, the Li cells we buy come from China.. 'nuff said.)



Russco said:


> Makes me sorta glad I've stuck with old fashioned flooded lead acid.


Well, your flooded PbA batteries are rather mature technology. I bet they weren't nearly so impressive back in the 60's... The 1860's, that is...


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## Dave Koller (Nov 15, 2008)

See the new U.S. battery? Be sure to look at the internal view of the RE-L16XC 

http://www.usbattery.com/usb_solar_p1.html

http://www.usbattery.com/usb_solar_renewable_energy_p2.html


Lead acid has come a looooong way


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## Tesseract (Sep 27, 2008)

Dave Koller said:


> ...
> Lead acid has come a looooong way


Precisely my point - it has 150 years of product development behind it!


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## DC Braveheart (Oct 12, 2008)

Russco said:


> With the recent low temperatures in Florida, Dimitri has found some out-of-whack Llthium cells. And Brian (of Volt Blocher fame) from California has also experienced bad lithium cells. Now Brian has his red Honda EV for sale in "The Trading Post."
> 
> Is lithium not all it's meant to be?
> 
> Makes me sorta glad I've stuck with old fashioned flooded lead acid.


Brian's blog says "After putting 10k miles on this one I feel comfortable selling it since I know it's been a good conversion and is reliable." ... so why do you think his selling the S2KEV means he is down on the LiFePo4 cells? I know he had some issues ... but I thought that was because he accidentally shorted a cell or two - or did I miss something?


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## dimitri (May 16, 2008)

All the issues with LFP are due to customers having to discover everything by trial and error, since specs are sketchy and often not very accurate or misleading. That along with products being continuously refined and improved. For example, they state 3C continuous discharge, which should mean truly 3C dump for 20 minutes and still work for 1000's of cycles. Well, I am now convinced this to be a total bullcrap. I would love to see anyone do this every day and not kill the cells within a year.

As I look back over a year of LFP usage, so much was learned by trial, if I was to start today, I would certainly make my pack much more resilient, by using larger cells and more of them in series.

So, bottom line, nothing wrong with Lithium, we just need to learn how to use it. Afterall, you don't see people putting UPS batteries in EVs, you know what works and what doesn't. Same with LFP, live and learn.


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## dimitri (May 16, 2008)

Also, forgot to mention temp issues, thanks to global warming, errrr... climate change  , we now have freezing season in Tampa, so I will be insulating batteries for my next conversions


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## JRP3 (Mar 7, 2008)

It also sounds as if Dimitri has some bad cells, maybe older stock as well and not the newer Aleees powder and yttrium chemistry.


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## dimitri (May 16, 2008)

JRP3 said:


> It also sounds as if Dimitri has some bad cells, maybe older stock as well and not the newer Aleees powder and yttrium chemistry.


Yes, both Brian and I bought from Elite Power and got some possibly older stock cells, and all of them before Aleees and Yttrium were introduced. I really hope better results will come from newer cells after at least a year of daily use across all temp ranges.

So, JRP3, get off your butt, finish your EV and start posting data


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## JRP3 (Mar 7, 2008)

Still too damn cold here with more on the way  I have to get this thing inside.


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## BMI/LiFeTech (Aug 12, 2009)

dimitri said:


> Also, forgot to mention temp issues, thanks to global warming, errrr... climate change  , we now have freezing season in Tampa, so I will be insulating batteries for my next conversions


We have been testing our LiFeTech LiFePO4 battery packs at sub zero temperatures (minus 20 deg C) and thankfully they have passed all tests.
You can see the frost on the sides of the battery as it is taken out of the freezer in readiness for the lab testing to begin.


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## paker (Jun 20, 2008)

Russco said:


> With the recent low temperatures in Florida, Dimitri has found some out-of-whack Llthium cells. And Brian (of Volt Blocher fame) from California has also experienced bad lithium cells. Now Brian has his red Honda EV for sale in "The Trading Post."
> 
> Is lithium not all it's meant to be?


Or could Jack Rickard be correct about battery management systems?


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## BMI/LiFeTech (Aug 12, 2009)

dimitri said:


> All the issues with LFP are due to customers having to discover everything by trial and error, since specs are sketchy and often not very accurate or misleading. That along with products being continuously refined and improved. For example, they state 3C continuous discharge, which should mean truly 3C dump for 20 minutes and still work for 1000's of cycles. Well, I am now convinced this to be a total bullcrap. I would love to see anyone do this every day and not kill the cells within a year.
> 
> As I look back over a year of LFP usage, so much was learned by trial, if I was to start today, I would certainly make my pack much more resilient, by using larger cells and more of them in series.
> 
> So, bottom line, nothing wrong with Lithium, we just need to learn how to use it. Afterall, you don't see people putting UPS batteries in EVs, you know what works and what doesn't. Same with LFP, live and learn.


Dimitri, your statements above only relate to poor quality cells made in China (such as Thundersky for example) whose manufacturing practices are poor and the final product goes through minimal quality control. This is the main reason why cells fail. 
Regarding your comments about cycle life, sure it is more than likely TS cells will fail prematurely but for very high quality LiFePO4 cells such as the LiFeTech cells we manufacture we stand by our claimed cycles life or else we would not be able to put a 3000 cycles / 3 years factory warranty (minimum) on our packs.


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## dimitri (May 16, 2008)

BMI/LiFeTech said:


> Dimitri, your statements above only relate to poor quality cells made in China (such as Thundersky for example) whose manufacturing practices are poor and the final product goes through minimal quality control. This is the main reason why cells fail.
> Regarding your comments about cycle life, sure it is more than likely TS cells will fail prematurely but for very high quality LiFePO4 cells such as the LiFeTech cells we manufacture we stand by our claimed cycles life or else we would not be able to put a 3000 cycles / 3 years factory warranty (minimum) on our packs.


Unfortunately Chinese cells are the only ones which are barely affordable for DIY market these days, so even 10% failure rate is somewhat acceptable IMHO. Looking back few years, when TS sold really crappy LC or LP cells to a bunch of people, what we have today is a huge improvement, so I think its going to get better and better.

Don't get me wrong, I think TS and SE cells are still much better alternative to Lead Acid, as long as you set your expectations correctly.

I will replace 3-4 cells later this year and will be a happy camper again


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## Tesseract (Sep 27, 2008)

BMI/LiFeTech said:


> ...for very high quality LiFePO4 cells such as the LiFeTech cells we manufacture we stand by our claimed cycles life or else we would not be able to put a 3000 cycles / 3 years factory warranty (minimum) on our packs.


Sounds great! Just a few questions for you:

1. Whether your cells are, indeed, superior to the equivalents made by TS or SE or not, the first question anyone is going to have is: *How much more do they cost?*

2. We can currently buy TS and SE cells from several dealers. At least one place has them in stock and "on the shelf" (Elite Power Solutions). *Where can we buy your cells?*

3. A 3000 cycle/3 year warranty sounds real good to me, assuming I don't have to send any defective cells back to Australia to make a warranty claim. *Who provides warranty service in the USA?*

4. Realize that the average person will not take your claims of superior performance, quality, longevity, whatever, at face value. You need to provide some form of proof - independent testing, reviews from known/trusted sources like fellow forum members, etc. - before ANYONE is going to treat your statements as anything more than advertising fluff. *Have you had your cells tested by an unbiased 3rd party or has any well-known member on a forum such as this one reviewed them?*

Now, I myself am a manufacturer of a product aimed at this community so I well know that you either "put up or shut-up". I am sure the DIY community would welcome another supplier of LFP cells - especially those suitable for full-size EVs (IMO, the market for small cylindrical cells, say 10Ah or less, is already saturated) - but please don't jump into every thread about batteries just to say how great your cells are... That's what we call "spam".


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## JRP3 (Mar 7, 2008)

Also coming to market now are 20ah prismatic A123 cells for $2.50 per ah. That's only twice the cost of TS and SE cells for an A123 cell. These are raw cells but this will put added price pressure on all cell makers.


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## dexion (Aug 22, 2009)

There is at least one place in the usa that you can get cells at 1.50 an ah with a 3 year warranty. And I have a good feeling they stand behind their warranty as well. But, do your research and see what meets your needs.


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## tomofreno (Mar 3, 2009)

> and thankfully they have passed all tests.


 That's nice. What were the test criteria?


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## jondoh (Sep 8, 2008)

Things go bad on on things that are supposed to be perfect -- like even your brand new gas car will probably have a recall or two before long.

The one TS cell that went bad I got replaced for nothing from EV Components.

I've had to replace most of the power tool batteries (under warranty) I've used in my ebike.

The fact is that batteries go bad for one reason or another. If you have support, you can deal with it.


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## Wirecutter (Jul 26, 2007)

This seems like as good a place for my little rant as any, so here goes...

Since getting the West Mountain CBA, I've been testing every little lithium battery I can get my grubbies on. When all my tests gave disappointing capacities, I started to read the specs even more carefully.

On more than one occasion, the spec will look like this: The battery is "rated" and sold as a 2600 mAh cell. Ordinarily, I'd take that to mean 2600 *minimum*, but that would be wrong. The spec will state (stipulating optimal conditions, of course) that the *minimum* is only 2500 mAh. The 2600 number is in the *nominal* column.

From what I've been able to tell, the larger format lithium polymer cells don't try this crap, but if you look at the smaller cylindrical cells, there's a bunch of smoke, mirrors, and outright lies in the specs. Of the last 20 *brand new* cells I've tested, *not one* has tested to the branded capacity. I've gotten up to 90%, but that's it.

Some background on my test conditions: All tests at room temp, about 23 C. All tests at 0.5C and below - usually I test 18650 2200mAh and 2600mAh cells at 1.0 amp. All tests are on cells that are charged at 0.25C rate or lower (500 mA). All tested cells are allowed to "rest" for at least 3 hours after either a charge or discharge. (on the advice of one of the forum members here.)

The biggest disappointment has been the 26650 LiMnNi cells I got from Battery Space. I put together a 4S pack with a HV/LV protection circuit. (Silly me - I welded tabs to it like you're supposed to when you make a real battery pack. Uh oh, can't RMA them!) The best I've seen from this pack has been around 3100 mAh, but the cells are all rated 4000 mAh with up to 2.5C max discharge. (but not both at the same time, of course)

So the moral is, caveat emptor. When I put an EV pack together, I'm testing every cell for capacity.
-M


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## yarross (Jan 7, 2009)

JRP3 said:


> Also coming to market now are 20ah prismatic A123 cells for $2.50 per ah. That's only twice the cost of TS and SE cells for an A123 cell.


Sounds interesting. Any source?


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## JRP3 (Mar 7, 2008)

Take a look over at endless sphere or PM me for details.


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## BMI/LiFeTech (Aug 12, 2009)

tomofreno said:


> That's nice. What were the test criteria?


We have been performing "arduous conditions testing" of our cells and battery packs. Some of our large customers have wanted us to perform certain tests. For example we just shipped a large qty of battery packs to China to power solar powered street lighting (photo attached showing part of one shipment). It says a great deal when the Chinese themselves will buy batteries from us for their own use in China (because they want very good quality) but won't touch their own product (Thundersky / Sky Energy etc). Of course they know their own factories better than anyone.

Some of the tests which we have been performing on our cells and packs are-
1) Cell learing and grading
2) Heat Source Analysis
3) Charging / discharing performance testing.
4) Battery EDS testing
5) Salt spray testing
6) Thermal shock testing
7) Battery vibration testing
8) High current discharge testing

I tried to attach the factory QC document showing photos of all these tests in our factory but unfortunately I am unable to do so. This forum won't allow me to attach a PDF document which is almost 3MB.

Each and every one of our battery packs which we supply our customers goes through stringent QC testing and when you open each battery box included is the actual factory test results for that particular battery.
I will take a photo of of a typical test result of one of these packs and post it here shortly.

We don't sell "crap" and of course due to our manufacturing practices, our investment of several million dollars in sophisticated cell and battery testing equipment this adds to the cost of the final product. Also all this testing of every battery is quite labour intensive.
We are mainly in the market with competetors like A123 Systems and our products are similar in price however we provide a complete packaged solution.
Our X2E series batteries are rated at 10C continous dicharge while our X1P series are rated at 30C continuos dicharge (35C peak). These are genuine figures and no exaggeration. I am not about to risk my good reputation in the industry by telling lies. My good name means everything to me.


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## BMI/LiFeTech (Aug 12, 2009)

jondoh said:


> Things go bad on on things that are supposed to be perfect -- like even your brand new gas car will probably have a recall or two before long.
> 
> The one TS cell that went bad I got replaced for nothing from EV Components.
> 
> ...


But it shouldn't be like that. You should be confident that every cell/battery you buy is A-grade with no faults. There is no excuse for receiving defective product even if it is only (one or two cells).
If factory quality control procedures were in place there would be no concern.
It is this acceptance by a consumer of accepting poor quality product which allows manufacturers to be sloppy.
The only battery you ever receive which could be faulty is the one which FedEx / UPS etc. drop as it is being shipped to you.
At the time it leaves the factory gates it should be in perfect condition and up to claimed specifications.


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## BMI/LiFeTech (Aug 12, 2009)

Tesseract said:


> Sounds great! Just a few questions for you:
> 
> 1. Whether your cells are, indeed, superior to the equivalents made by TS or SE or not, the first question anyone is going to have is: *How much more do they cost?*
> 
> ...


1)We are in the market with competetors like A123 Systems and our products are similarly priced however we provide a complete packaged solution (all battery management and data generation for use by external controls is inbuilt into the pack)

2)Our batteries are not available "off the shelf" since each pack is custom assembled and individually factory tested upon order. This helps with quality control and traceability. Also our batteries may or may not require programming of ID addresses for external PC monitoring. Therefore we make each battery to suit the customers requirements for their given application. Batteries are shipped direct from the factory to the customer to keep shipping costs to a minimum.

3)I am sorry to hear you have the "Thundersky mentality" (whereby you expect to have some faulty cells). Our product is not like this and you should expect to have NIL failures (more than 3 million USD in battery grading and testing equipment is our backup for this claim).
In the highly unlikely event of a warranty claim the battery in most cases gets sent back to the factory for a replacement. 
I am talking to one of our US customers (an EV conversion company from Oklahoma) who may become an agent for us in the USA and keep some of our products in stock as well as provide some technical service.

I am actually providing 5 years waranty to certain customers including a project to build some electric patrol boats.
The issue which is hard to deal with in the DIY market is knowing the level of competance of the customer. This is one reason why some companies such as A123, SAFT, etc. won't get into the end user market. I don't mind providing a long waranty if I know the customer is technically competant. It is very difficult when a customer makes a warranty claim when they have damaged the battery by either lack of knowledge of sheer stupidity (don't get me started, you won't believe some of the thinks I have seen customers do and try to claim warranty). 

4)Our batteries are already in use in EV's from many different countries. We power the worl'ds fastest production e-bike manufactured in Europe (Austria). We have been more focussed on the electric boating market recently but I am sure you will hear more about use soon (see attached boating magazine article).
Our cells have been tested by independant US labs as well as our own exhaustive factory testing. Feel free to email me and I will be glad to send you the test reports/discharge curves, etc.

Several members over on the ES forum (including from the USA and Canada) have used our batteries for e-bike applications and will attest to their superior performance. I would be happy to put you in touch with these members directly if you wish.

It sounds like you feel threatened by a quality product being available.


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## JRP3 (Mar 7, 2008)

Well if a product is available but not affordable it's not actually a valid option. Very often a lesser quality product is good enough. TS or SE cells even with a 10% failure rate are still far cheaper than other options and make projects possible that otherwise would not be. I'd like to build a vehicle with an ACP drive train and A123 or Phostech cells, but I can't afford it, by a long shot.


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## jorhyne (Aug 20, 2008)

Here is a link to lifebatt retail prices: http://www.lifebatt.com/retail_sheet.html

The truth is that as long as that lifebatt prices are nearly 5 times the cost of raw thundersky cells ($910 for a 12v 40AH battery? really!?) then the average DIYer will not buy them. No one is going to argue that Thunderskys are higher quality but lifebatt still has the same problem that lithium had two years ago, its freaking expensive! And yes I know your product includes a BMS and has CAN abilities and all that but it is still out of the price range of most of us.


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## sjc (Oct 28, 2008)

JRP3 said:


> Still too damn cold here with more on the way  I have to get this thing inside.


Ha! Come 40 miles north, you whinger!

32" of snow so far this month...in 9 days.

Drove through Ithaca on the way up from Findley Lake on the 3rd, trying to dodge the big snowfall on the Thruway. Didn't see you out in your E-ATV...but then I don't know where you live!

sc
--


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## Grant_NZ (May 28, 2008)

In reference to LifeTech, I’m a little confused in regards LiFePo pack sizing. If I have a motor that needs 144volts, I’d need 45 batteries (144/32=45) and if I want distance Id go for higher amp hours. Therefore 200Ah would do nicely (coz money grows on trees) however and finally my question why would I purchase a144v 15Ah pack?


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## BMI/LiFeTech (Aug 12, 2009)

jorhyne said:


> Here is a link to lifebatt retail prices: http://www.lifebatt.com/retail_sheet.html
> 
> The truth is that as long as that lifebatt prices are nearly 5 times the cost of raw thundersky cells ($910 for a 12v 40AH battery? really!?) then the average DIYer will not buy them. No one is going to argue that Thunderskys are higher quality but lifebatt still has the same problem that lithium had two years ago, its freaking expensive! And yes I know your product includes a BMS and has CAN abilities and all that but it is still out of the price range of most of us.


I am not sure where you got that Lifebatt price list from but it is no longer current since none of the batteries on that list are made any longer. The entire HPS series was superceeded about four months ago and replaced by the improved X1P, X1E and X2E series. The X2P series is expected to be available soon.
I perfectly understand the situation as far as cost goes. It is a very expensive product to manufacture. It would be nice if there was some way to bring the cost down so it became more affordable for the masses.
If you saw the automated robotics and machinery in a factory which manufactures the cells you would better understand the complexity and the difference in technology required to manufacture a LiFePO4 battery compared to a lead acid battery.
Hopefully there will be some reduction in price in the coming years but who knows how long that may be.


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## BMI/LiFeTech (Aug 12, 2009)

JRP3 said:


> Well if a product is available but not affordable it's not actually a valid option. Very often a lesser quality product is good enough. TS or SE cells even with a 10% failure rate are still far cheaper than other options and make projects possible that otherwise would not be. I'd like to build a vehicle with an ACP drive train and A123 or Phostech cells, but I can't afford it, by a long shot.


Yes, JRP3 I understand what you are saying.
All I would say is that most people just look at the initial cost (which is what scares them-understandably). They don't look at the bigger picture ie, the actual cost of the battery calculated as dollars per charge over its expected working life.
Were you aware that even the premium performance and most expensive batteries like A123 and LiFeTech Phostech cells work out to be around 70% of the cost of lead acid when all factors are taken into consideration over the entire life of the pack? This is calculated using an electric motor as a load so is a perfectly relevant example to use for EV use.


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## BMI/LiFeTech (Aug 12, 2009)

Grant_NZ said:


> In reference to LifeTech, I’m a little confused in regards LiFePo pack sizing. If I have a motor that needs 144volts, I’d need 45 batteries (144/32=45) and if I want distance Id go for higher amp hours. Therefore 200Ah would do nicely (coz money grows on trees) however and finally my question why would I purchase a144v 15Ah pack?


It appears you are a bit confused about how our packs work.
Each 144V battery pack is either 10Ah or 15Ah depending on the battery series.
Sure the battery has data connectors for connecting to your computer for doing all sorts of fancy stuff but for the purpose of a simple reply just think of it as a 144V lead acid battery ie, there is 144V at the battery terminals. Of course you don't see the stuff inside which makes this all happen (cells, copper cell links, cell holders, fuseable links, termperature sensors and multiple VMS circuit boards). 

So LiFeTech battery methodology is very different to Thundersky methodology. Each Thundersky cell is 3.2V so you connect cells in series to obtain the required operating voltage. Since cells are in series the battery is only as good as the weakest cell (weakest link in the chain). If one cell fails you have considerable problems.
With LiFeTech batteries each pack is 144V so you simply hook them up in parallel to obtain the required total battery capacity (and therefore driving range per charge). Often a customer will buy a few packs to start with (what their budget will allow) and when they have saved up some more money, perhaps a year or so later, they simply buy more packs and connect them in parallel to increase driving range. 
So if one pack was to have a problem (never happened to date) it is easy to remove and doesn't cause as big a problem as cells connected in series since you still have 144V available and the only thing which is reduced slightly is the total capacity.

I am not sure where in NZ you are located but I just shipped some packs to Christchurch to power an electric boat. If you are in Christchurch I am sure the boatbuilder wouldn't mind showing you the batteries so you understand how they work.


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## Tesseract (Sep 27, 2008)

BMI/LiFeTech said:


> It appears you are a bit confused about how our packs work.
> Each 144V battery pack is either 10Ah or 15Ah depending on the battery series.
> ...
> So LiFeTech battery methodology is very different to Thundersky methodology. Each Thundersky cell is 3.2V so you connect cells in series to obtain the required operating voltage. Since cells are in series the battery is only as good as the weakest cell (weakest link in the chain). If one cell fails you have considerable problems.


Unless you have access to a secret periodic table of elements with much higher Pauling electronegativities than we have here on Earth, then you need to put a bunch of 3.2V cells in series to get to 144V just like anybody else would.

So, your batteries are only as strong as their weakest cell, too. In fact, EVERYBODY'S battery packs are only as strong as their weakest cell.

Now, if you really wanted to flatten out the differences between cells - force them to self-equalize, more or less - then you would need to put every single cell in parallel with it's equipotential brothers. This is a subtle, but important, difference from the way you are doing it.


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## Tesseract (Sep 27, 2008)

BMI/LiFeTech said:


> ...
> It sounds like you feel threatened by a quality product being available.


  


(Perhaps you should click on the link in my signature to see why I think your comment is hilarious).


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## Jimdear2 (Oct 12, 2008)

I think I see where BMI/LiFeTech battery is coming from. They sell assembled batteries. A sealed case contains all of the 20 AH cells needed to make what they call a 20AH 144 volt battery.

Want more capacity, buy another cased set of cells and parallel it. Want lesser or a different voltage, the internal cell count is changed.

I assume (watch that, word it can make an ass of u and me) that each cased battery has has the individule cells rigorously tested and matched and contains the necessary BMS to protect the cells.

Not a bad idea as long as their quality control is at the standard they claim AND their warrenty will replace a complete cased battery if one internal cell goes bad. 

A plus to this construction, is it sure would save a lot of battery and rack assembly time. A minus you are stuck with their battery case dimensions and unless they offer custom caseing or have a large number of different format cases for the same capacities, fitting them will be like useing the old lead acid batts. 

Do the offer custom casing, colors and materials, if so I can see a big plus for one off's

It looks like their casing dimensions are based around large purpose built systems where placement is secondary or the system is built around the battery dimension. No hiding a couple of cells in a convienient corner, or shaping a pack to fit an irregular shape. 
*Question* will their battery live if placed on it's side.

Their construction is not a good idea if they let questionable cells get into their batteries because it doesn't look like they are repairable in the field and the factory is a LOOOOOONG way away.

So Some Good Points and some Bad Points (for EV construction)

The premise behind their battery construction is such that their quality control MUST be high or they will be out of business very soon.

The major scare on these batteries is their cost. Maybe a big battery company can get a major bank interested in loans to purchase these batteries (many of which cost as much as a small car.) If that happened maybe we would see these batteries blossom out into solar/wind/hydro home and vacation home use. Then there is the RV and marine areas.


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## JRP3 (Mar 7, 2008)

BMI/LiFeTech said:


> Yes, JRP3 I understand what you are saying.
> All I would say is that most people just look at the initial cost (which is what scares them-understandably). They don't look at the bigger picture ie, the actual cost of the battery calculated as dollars per charge over its expected working life.
> Were you aware that even the premium performance and most expensive batteries like A123 and LiFeTech Phostech cells work out to be around 70% of the cost of lead acid when all factors are taken into consideration over the entire life of the pack? This is calculated using an electric motor as a load so is a perfectly relevant example to use for EV use.


We aren't comparing to lead acid we are comparing to TS and SE lithium. Since they are so much cheaper than what you offer they could have half the cycle life of your cells plus a 10% failure rate and still be a better deal in the long run.
I don't know the actual manufacturing differences between your cells and TS/SE but I'd guess they are both automated processes. I would imagine as the processes get more refined you would be able to spend less on testing and QC as the cells should come out closer to spec every time. One problem with a higher number of smaller cells is you have more chances for problems to arise and more things to check and keep track of.


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## BMI/LiFeTech (Aug 12, 2009)

Tesseract said:


> Unless you have access to a secret periodic table of elements with much higher Pauling electronegativities than we have here on Earth, then you need to put a bunch of 3.2V cells in series to get to 144V just like anybody else would.
> 
> So, your batteries are only as strong as their weakest cell, too. In fact, EVERYBODY'S battery packs are only as strong as their weakest cell.
> 
> Now, if you really wanted to flatten out the differences between cells - force them to self-equalize, more or less - then you would need to put every single cell in parallel with it's equipotential brothers. This is a subtle, but important, difference from the way you are doing it.


You clearly missed the point. I was merely pointing out that a LiFeTech battery is a professionally packaged product (you don't see any cells, wiring or circuit boards) compared to TS where you have to fit cells in series. The LiFeTech XPS cells are closely matched/impedance tested during the grading process so they all have the same charging/discharging performance. Even if the pack was made up of only cells without any cell balancing electronics you could cycle a battery several hundred times before you would start to see an imbalance in cells. 
Our 12V engine start batteries for ICE vehicles do not perform any cell balancing and the cells stay well in balance.


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## ellweber (Jun 3, 2009)

BMI/LiFeTech said:


> You clearly missed the point. I was merely pointing out that a LiFeTech battery is a professionally packaged product (you don't see any cells, wiring or circuit boards) compared to TS where you have to fit cells in series. The LiFeTech XPS cells are closely matched/impedance tested during the grading process so they all have the same charging/discharging performance. Even if the pack was made up of only cells without any cell balancing electronics you could cycle a battery several hundred times before you would start to see an imbalance in cells.
> Our 12V engine start batteries for ICE vehicles do not perform any cell balancing and the cells stay well in balance.



If you spent half as much time providing detail about your product's performance and pricing as you spend on writing useless "MARKETING/SALES" fluff you might actually generate some real business!


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## jorhyne (Aug 20, 2008)

ellweber said:


> If you spent half as much time providing detail about your product's performance and pricing as you spend on writing useless "MARKETING/SALES" fluff you might actually generate some real business!


Haha I couldn't agree more. You really don't need to post all over forums singing the virtues of your products. Us DIYers are a pretty curious bunch, if there is a product out there that is relevant to our interests, we will probably discover it, and are even more likely to share it with the community. 

When was the last time you saw Thundersky out defending and advertising its products through overly wordy posts?


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