# A123 M1-B Tests



## dougingraham (Jul 26, 2011)

They don't seem to have much sag at all with a 2C discharge. Probably be a pretty decent cell if they had been available at an affordable price. Be a lot easier to assemble packs with these than with the smaller cells. I am thinking a motorcycle pack.

Thanks for posting. Got any photos?


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## tomofreno (Mar 3, 2009)

Thanks major. The cells in the first sample seem to match very well. Any idea of the cell temperature range during the test?


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## major (Apr 4, 2008)

dougingraham said:


> Thanks for posting. Got any photos?


I'll bring my camera tomorrow.

Tomo,

No temperature measurements, but my calibrated fingers detected no rise at all. Interesting package for these cells in that there is provision for fluid cooling on one end. They must have been intended for a hybrid application.

And on sample #2 where I stopped the test when cell #4 deviated 500 mV it is now back to balance within 6 mV during charge at 3.333 V/c and still charging off my 6 amp power supply.


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## agniusm (Apr 30, 2012)

Sounds like they are made of 8AH A123 cells, AHR32157M1-B:








Capacity: 7-8Ah
Nominal Voltage: 3.3V
Cell Dimensions: 32mm*157mm 
Weight: 252g
I was quoted at ~15USD per cell a month or so back.


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## Genius Pooh (Dec 23, 2011)

agniusm said:


> Capacity: 7-8Ah
> Nominal Voltage: 3.3V
> Cell Dimensions: 32mm*157mm
> Weight: 252g
> I was quoted at ~15USD per cell a month or so back.


why this cell is heavier and more expensive than older one..

20 ah cell now selling at Ebay 29$ 

Am I wrong?


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## Genius Pooh (Dec 23, 2011)

major said:


> I
> I used my constant current load tester and CellLog8s to gather data.


Can you tell me what is your tester?

I will buy one.. I curious what you have  ( I think It's quiet expensive.. but I want to know at least )


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## major (Apr 4, 2008)

Genius Pooh said:


> Can you tell me what is your tester?


Homemade 










Resistor load bank.










Power electronic regulator.


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## major (Apr 4, 2008)

dougingraham said:


> Got any photos?


Here ya go


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## Ziggythewiz (May 16, 2010)

major said:


> Resistor load bank.


How many amps can you pull with that beast?


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## major (Apr 4, 2008)

Ziggythewiz said:


> How many amps can you pull with that beast?


The resistors are good for maybe 40 or 50 kW. Can be configured many ways in series/parallel. My converter/regulator (big buck converter) is good to 400V, 400A, not both together with those resistors, at least not for long. IIRC, the most I've pulled is about 300A at 200V.


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## Karter2 (Nov 17, 2011)

Does anyone have a "spec" sheet for these cells ?
Specifically what the rated continuous and burst amps or "C" rate is ?

Most A123 is 30C rated, but i cant find anything for these.
How about a 200A discharge test on one cell Major ??


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## major (Apr 4, 2008)

Karter2 said:


> How about a 200A discharge test on one cell Major ??


I'm not sure I can get 200 A on a single cell. I can do up to 125 A at that low of voltage using another load. I'll see what I can swing next week. Or maybe my converter will work with just the inductor and no resistors to get that high of current with just a 2 or 3 volt source.

In the mean time, I ran a second test on sample #2 after I recharged it and top balanced it.










As you can see, compared to Test #1 on Sample #2 in the first post, I got another 5 Ah and cell #4 is back with the pack.


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## kennybobby (Aug 10, 2012)

*that is quite impressive*

Do you have a block diagram or simple schematic of your homemade test rack--curious minds want to know...


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## major (Apr 4, 2008)

*Re: that is quite impressive*



kennybobby said:


> Do you have a block diagram or simple schematic of your homemade test rack--curious minds want to know...


Not really. It is just your classic buck converter with an adjustable current limit and a rack of 24 locomotive braking resistors which can be configured in various series and parallel combinations. From memory, I think each resistor is about 100 to 200 mΩ and like 1 to 2 kW continuous rated. I've got 4 healthy fans on the bottom of the rack blowing up.

I put the converter together with odd parts salvaged from failed equipment and those change time from time. Right now it has a PowerEx 600A module for the main switch and uses a Semikron 500A module for the FWD. Throw in some caps, power supplies, DCCT and gate driver board and there you go. I have the modules mounted on a heat sink with a fan on top. 

The resistors are edge wound elements and provided enough inductance. I got concerned when I configured for low voltage and added an inductor just this past year. It really reduced the load ripple and those resistors don't sing like they use to 

I built it about 10 years ago. I don't use it every day. Had a few mishaps. You can see some blackened marks on the photo.


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## h0tr0d (Mar 26, 2012)

Awesome!

reliable suppliers of those cells?

thanks


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## major (Apr 4, 2008)

h0tr0d said:


> reliable suppliers of those cells?


Don't think so  What you see from me are old samples from a few years ago. I'm just playing with them. Speaking of which, I tried to get 200A on a single cell by bypassing the load resistors and just using the inductor on the output of the chopper. But it only went to 100A. The voltage across the inductor was 0.5V. That 600A, 1200V IGBT has too much voltage drop.

So I will have to resort to contactors and resistors. Contactors should live at the low voltage and I can use open frame units where I can clean the buttons if they arc too much. The resistor may become a length of welding cable. The downside is the current will not be regulated (constant) for the duration of the test. But it should give me a decent look at HI-C


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## Ziggythewiz (May 16, 2010)

I've heard a wrench in a bucket of water makes a decent resistor


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## dougingraham (Jul 26, 2011)

major said:


> Speaking of which, I tried to get 200A on a single cell by bypassing the load resistors and just using the inductor on the output of the chopper. But it only went to 100A. The voltage across the inductor was 0.5V. That 600A, 1200V IGBT has too much voltage drop


For low voltage operation you can probably replace your 600A IGBT with 6 paralleled IRFP4004PBF. This would have a resistance of about 0.00028 ohms. At 600 amps this would give a voltage drop of 0.168 volts and about 100 watts of waste heat divided over 6 parts is about 17 watts per part. This would be running them at about half power. With these packages you could probably get by with a small heatsink and fan. At 200 amps you wouldn't even need a heatsink as the waste heat would be only 1.8 watts per package and they can dissipate that into free air. Downside is only good to about 30 volts in your application. You can probably use the same drive circuitry as the IGBTs.

These are TO-247 packages and there are lower resistance parts available in surface mount but the thru hole parts are easier to deal with in an application like this.


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## dougingraham (Jul 26, 2011)

h0tr0d said:


> Awesome!
> 
> reliable suppliers of those cells?
> 
> thanks


There used to be a datasheet for these on A123's website. I never saw them offered for sale or used in a product until now. I was comparing them to the equivalent Headways and they were at least on paper a bit better.

http://http://www.a123systems.com/32113-lithium-iron-phosphate-high-power-batteries.htm

This is the data sheet I was remembering. But it is not for the cells in this thread. A123 doesn't have this cell on the web site.

One can hope that since A123 was sold that these will start showing up for sale at a reasonable price. I think they would make a decent pack for casual racing.


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## major (Apr 4, 2008)

dougingraham said:


> For low voltage operation you can probably replace your 600A IGBT with 6 paralleled IRFP4004PBF. This would have a resistance of about 0.00028 ohms. At 600 amps this would give a voltage drop of 0.168 volts and about 100 watts of waste heat divided over 6 parts is about 17 watts per part. This would be running them at about half power. With these packages you could probably get by with a small heatsink and fan. At 200 amps you wouldn't even need a heatsink as the waste heat would be only 1.8 watts per package and they can dissipate that into free air. Downside is only good to about 30 volts in your application. You can probably use the same drive circuitry as the IGBTs.
> 
> These are TO-247 packages and there are lower resistance parts available in surface mount but the thru hole parts are easier to deal with in an application like this.


Thanks doug,

I knew that  But I am trying to get by with what I have in the lab without buying new parts. And a bunch of small package mosfets would be a bitch to wire into the old chopper. 

major


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## major (Apr 4, 2008)

Karter2 said:


> How about a 200A discharge test on one cell Major ??


O.K. So I put the two loose cells in series and onto the chopper with just the inductor on the output. I was able to get 200 Amps  I wasn't set up to record any data, but the cells stayed above 2 volts and I went about 15 seconds at a solid 200A. Chickened out and shut it down. IR thermometer showed cell body up at 117ºF.

The 6P6S battery is labeled 44.4 Ah, so that is 7.4 Ah per cell. 200A is then 27C. The 6P battery will do 1200A


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## Karter2 (Nov 17, 2011)

I assume that was "above 2 volts" per cell, ..not above 2 volts for both in series ?


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## Karter2 (Nov 17, 2011)

h0tr0d said:


> Awesome!
> 
> reliable suppliers of those cells?
> 
> thanks


 Reliable ?? dont know about that , but there are plenty of sources such as this..
http://www.a123rc.com/goods-474-Hig...Ion+Battery+LiFePO4+Battery+(A123+32157).html


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## h0tr0d (Mar 26, 2012)

what about these guys?
http://www.a123rc.com/goods-474-Hig...Ion+Battery+LiFePO4+Battery+(A123+32157).html

or OSN power...

What I need is a 30S 250A peak battery.
Any thoughts?


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## Ziggythewiz (May 16, 2010)

h0tr0d said:


> What I need is a 30S 250A peak battery.
> Any thoughts?


A 100 lbs pack of CA40s would do nicely.


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## major (Apr 4, 2008)

Karter2 said:


> I assume that was "above 2 volts" per cell, ..not above 2 volts for both in series ?


Yes, above 2 V/c. I'll likely try to hook up a data logger and repeat the test next week f.t.h.o.i.


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## Brute Force (Aug 28, 2010)

I was looking at these cells just over a year ago. At the time, A123 showed them on their web site, but had no specs available. Then the info on the A123 web site vanished. Mavizen (the only genuine A123 dealer) was unaware of the existence of this cell. The Chinese gray market was the only source for these and I was not brave enough the spend $$$ on a batch.


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## Karter2 (Nov 17, 2011)

h0tr0d said:


> What I need is a 30S 250A peak battery.
> Any thoughts?


How much capacity do you need..1kWhr or 50kWhr ..
...it makes a BIG difference to your options.


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## njloof (Nov 21, 2011)

Man, A123RC used to sell the AMP20 pouches... guess the supply has dried up.


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## GerhardRP (Nov 17, 2009)

major said:


> O.K. So I put the two loose cells in series and onto the chopper with just the inductor on the output. I was able to get 200 Amps  I wasn't set up to record any data, but the cells stayed above 2 volts and I went about 15 seconds at a solid 200A. Chickened out and shut it down. IR thermometer showed cell body up at 117ºF.
> 
> The 6P6S battery is labeled 44.4 Ah, so that is 7.4 Ah per cell. 200A is then 27C. The 6P battery will do 1200A


Did you look at the terminal temperatures. I seem to recall that the positive electrode gets hottest on discharge.
Gerhard


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## major (Apr 4, 2008)

GerhardRP said:


> Did you look at the terminal temperatures. I seem to recall that the positive electrode gets hottest on discharge.
> Gerhard


I moved the laser dot all around and the body appeared warmest. I'll look more carefully next time.


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## h0tr0d (Mar 26, 2012)

Karter2 said:


> How much capacity do you need..1kWhr or 50kWhr ..
> ...it makes a BIG difference to your options.


Forgot to mention that...

I'm in the market for the lightest, yet stable, ~100V battery capable of 250A peak, 100A continuous. 10 (Ten) lbs would be nice.
A 30S2P A123 32157 would be perfect...
Does anyone have a better idea?



> Man, A123RC used to sell the AMP20 pouches... guess the supply has dried up.


These are no longer in stock?
http://www.a123rc.com/goods-468-Excitingly+Powerful+A+123+20ah+PRISMATIC+CELLS.html

.


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## njloof (Nov 21, 2011)

Ah, guess I'm wrong! I could swear I paid closer to $40 back in the day...


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## GeoMetric (Aug 13, 2010)

h0tr0d said:


> Forgot to mention that...
> 
> I'm in the market for the lightest, yet stable, ~100V battery capable of 250A peak, 100A continuous. 10 (Ten) lbs would be nice.
> A 30S2P A123 32157 would be perfect...
> ...


K2 Energy Solutions.
http://www.k2battery.com

http://electricmotorsports.proboards.com/index.cgi?board=6576567&action=display&thread=14


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## h0tr0d (Mar 26, 2012)

GeoMetric said:


> K2 Energy Solutions.
> http://www.k2battery.com
> 
> http://electricmotorsports.proboards.com/index.cgi?board=6576567&action=display&thread=14


Thanks for the suggestion.
I'm a bit confused, the official k2 website states 50A per 2.6Ah cell, your link suggests 100A (40C)...

Anyone one here has tried K2?


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## Karter2 (Nov 17, 2011)

h0tr0d said:


> Forgot to mention that...
> 
> I'm in the market for the lightest, yet stable, ~100V battery capable of 250A peak, 100A continuous. 10 (Ten) lbs would be nice.
> A 30S2P A123 32157 would be perfect...
> ...


 ?? you still didnt tell us what capacity ( Ahr's or kWhrs ) you need ?

Those 20Ahr, A123 pouches are still available from several vendors on the net.
Some will assemble them into packs also.( EG..OSNPower)


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## GeoMetric (Aug 13, 2010)

Karter2 said:


> ?? you still didnt tell us what capacity ( Ahr's or kWhrs ) you need ?
> 
> Those 20Ahr, A123 pouches are still available from several vendors on the net.
> Some will assemble them into packs also.( EG..OSNPower)


Those Chinese reject A123 20AH pouch cells are time-bombs! They have leaked, caught fire, etc...in many applications.


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## GeoMetric (Aug 13, 2010)

h0tr0d said:


> Thanks for the suggestion.
> I'm a bit confused, the official k2 website states 50A per 2.6Ah cell, your link suggests 100A (40C)...
> 
> Anyone one here has tried K2?


They have been tested and proven, here is addition info:
*26650P*

When high power is essential, this battery delivers with a burst of *150A *from a single cell. 

*FEATURES:*



2.6Ah Real Capacity
<9mOhm
Over 40A of continuous discharge
 
http://www.k2battery.com/products-26650P.html

The cells produce similar burst rating as the A123 M1 cell, but deliver more energy. This info is also on the Elithion website. With all cells, the higher discharge the more sag. On this link it provides tested sag voltage at 150A and lower, I think you did not read all the charts. All published data is directly from the company engineer Jim Hodge, I can forward his emails with data if anyone is interested in K2 Energy cells.

http://electricmotorsports.proboards.com/index.cgi?board=6576567&action=display&thread=14&page=1


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## GeoMetric (Aug 13, 2010)

Single LFP26650P cells:

This cell is 26.2mm D x 65.2mm H and weights 82.5 grams.

Another great link for info:

https://batteryworkshop.msfc.nasa.gov/presentations/Mod_LFP_Batt_Large_Format_App_JHodge.pdf


Please contact us at (702) 478-3590 or email us at [email protected] for large quantity order pricing, for distribution and/or OEM opportunities, and for any custom battery solution that you may need.


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## h0tr0d (Mar 26, 2012)

Karter2 said:


> ?? you still didnt tell us what capacity ( Ahr's or kWhrs ) you need ?
> 
> Those 20Ahr, A123 pouches are still available from several vendors on the net.
> Some will assemble them into packs also.( EG..OSNPower)


I only need around 100Wh... energy is not really that important in my application.

Building a 30S with 20Ah pouches would be a bit bulky and way overkill in terms of energy.


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## GeoMetric (Aug 13, 2010)

Additional data on the K2 Energy 73AH power modules:

http://www.nemrs.net/k2energybatteries.html

Maximum Operating Conditions:

Continuous discharge 30 seconds 1200A
Pulse discharge 5 seconds 4200A

This data is only for the modules built with the 26650P cells. They do sell cells for lower discharge applications.


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## GeoMetric (Aug 13, 2010)

This info was emailed to me by the head engineer, it relates to the 26650P cell and what they produce when built into a 73AH modules. The company does sell and build custom smaller modules for different applications


 Facts I have confirmed with K2 Energy engineers:

When our batteries have plenty of state of charge in them, you won’t harm them by discharging at 1.6V (~3000Amps in our 73Ah module). As they get hot, it will reduce their cycle life…but it also helps with their discharge voltage level (being warmer raises the voltage).

For a 3000 A discharge, our 73Ah module will have a voltage of 1.6V. 2500A would put you at about 2.0V on one of our 73Ah modules.

A couple of graphs that should help. 2500 A out of a single 73Ah module translates to 89A per cell. At 50A, our power cells will sustain the ~2.4V level for roughly 2.25 minutes
Read more: http://electricmotorsports.proboard...action=display&thread=14&page=1#ixzz2LDX9uP6J
​


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## h0tr0d (Mar 26, 2012)

GeoMetric said:


> This info was emailed to me by the head engineer
> 
> A couple of graphs that should help. 2500 A out of a single 73Ah module translates to 89A per cell. At 50A, our power cells will sustain the ~2.4V level for roughly 2.25 minutes
> ​


Thank you for the inside info

Using K2 stuff, I would need 30S 5P right? [email protected] (22C) is a lot of voltage sag. A123 M1B's have lower internal resistance right?


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## Karter2 (Nov 17, 2011)

The lightest, cheapest, simplest, way for you to get 100 v and 100A would be the nanotec Lipo
4 of these 6s, 4Ahr, would weigh less than 3 kg, cost under $400 and give 500A burst.


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## Jozzer (Mar 29, 2009)

h0tr0d said:


> Thanks for the suggestion.
> I'm a bit confused, the official k2 website states 50A per 2.6Ah cell, your link suggests 100A (40C)...
> 
> Anyone one here has tried K2?


 Yes, I tested 150 a couple of years back, they were not as good as the A123 M1 cell - and IR wasn't very consistant out of the box..


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## GeoMetric (Aug 13, 2010)

Jozzer said:


> Yes, I tested 150 a couple of years back, they were not as good as the A123 M1 cell - and IR wasn't very consistant out of the box..


Jozzer, again you attack any person or company that competes with your sales of Turnigy cells. On the Elithion website it states:

*K2 Energy Solutions *



 The LFP26650P is a comparable to the A123 M1
 The LFP26650EV has more energy but even higher DC resistance
 The LFP165EVS and LFP300EVS are actually assemblies of small cylindrical cells in a prismatic case
 Ease of connections of prismatics
 Reliability and good thermal characteristics of small cylindricals
 
 They will weld cells for you in blocks
 They sell a 5P4S block, and a 26P1S brick, of either the LFP26650P or LFP26650EV cells
 When exposed to flames, nothing bad happens
http://liionbms.com/php/cells.php#K2_Energy


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## GeoMetric (Aug 13, 2010)

Karter2 said:


> The lightest, cheapest, simplest, way for you to get 100 v and 100A would be the nanotec Lipo
> 4 of these 6s, 4Ahr, would weigh less than 3 kg, cost under $400 and give 500A burst.


Definitely playing with fire using any series built R/C battery for use in motorcycle or EV vehicle. The wires are soldered to the tabs "weak spot" and using balance wires to create a BMS is very dangerous! Look at how many fires have started using R/C packs. I am sure I will now get attacked by Jozzer and his 5 alias names, stating he has used them for years etc....but the truth is in the facts!


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> Jozzer, again you attack any person or company that competes with your sales of Turnigy cells. On the Elithion website it states:
> 
> *K2 Energy Solutions *
> 
> ...


 I'm not attacking anyone - someone asked if anyone had tried them, so I gave my feedback. This is actually a thread about A123 - YOU were the one who hijacked it to offer a product from your sponsors (despite the fact you've not tried them yet!).


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> Definitely playing with fire using any series built R/C battery for use in motorcycle or EV vehicle. The wires are soldered to the tabs "weak spot" and using balance wires to create a BMS is very dangerous! Look at how many fires have started using R/C packs. I am sure I will now get attacked by Jozzer and his 5 alias names, stating he has used them for years etc....but the truth is in the facts!


 ROn - that IS an attack - I don't have ANY alias names at all. 
I think you owe me ANOTHER apology!


Steve


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## GeoMetric (Aug 13, 2010)

Jozzer said:


> I'm not attacking anyone - someone asked if anyone had tried them, so I gave my feedback. This is actually a thread about A123 - YOU were the one who hijacked it to offer a product from your sponsors (despite the fact you've not tried them yet!).


Yes, I'm sure you tested them. 
You seem to pop-up any time I post a battery product. 

I have had them tested with excellent results. There is a reason K2 Energy is still in business and A123 had to file bankruptcy. 

Can you give us all the Turnigy fail rate?


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## major (Apr 4, 2008)

Jozzer said:


> - someone asked if anyone had tried them, so I gave my feedback.


Thanks Jozz, as the guy who started this thread, I appreciate your input


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## Jozzer (Mar 29, 2009)

major said:


> Thanks Jozz, as the guy who started this thread, I appreciate your input


Hehe - I did wonder how this got turned into a K2 sales thread..


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> Yes, I'm sure you tested them.
> You seem to pop-up any time I post a battery product.
> 
> I have had them tested with excellent results. There is a reason K2 Energy is still in business and A123 had to file bankruptcy.
> ...


Calling me a liar Ron? Maybe I "pop up" because you keep starting threads saying that "XXX Cell" is the best in the world despite you having next to no experience with them.

I have shared freely all my results from Turnigy - the good and the bad - all here on this forum to find.
This is not the place however, this is an A123 thread...

Funny how whatever cell you are being sponsored with this year is the best one in the world and all the others will catch fire and kill everyone 

Back on topic - the M1 IS a very very good cell - despite being a good few years old now. I've still got lots in little project vehicles and they have proven some of the longest lasting and reliable battery's I've ever had (and I've tried a few - despite what Ron says!).

Edited to add - In fact, I've just remembered I have a 13Ah 12v (4s5p) pack of them as the Aux battery in my Mercedes Sprinter diesel van. I put them in 3 years ago as a temporary fix when the PB batt died, and they have been cranking the van over come rain or shine ever since!


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## GeoMetric (Aug 13, 2010)

h0tr0d said:


> Forgot to mention that...
> 
> I'm in the market for the lightest, yet stable, ~100V battery capable of 250A peak, 100A continuous. 10 (Ten) lbs would be nice.
> A 30S2P A123 32157 would be perfect...
> ...


This is why I posted the K2 Energy products. They are similar to A123 cells and easy to purchase. You can also build them in parallel blocks which allows the use of a proper BMS.


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## Jozzer (Mar 29, 2009)

http://www.diyelectriccar.com/forums/showthread.php/a123-vs-k2-energy-52433.html

Post #6 - you'll see I said exactly the same thing way before I opened shop - and that it was NOT an attack upon you.


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## h0tr0d (Mar 26, 2012)

Thank all for the tips.

Just received a quote 90 cells A123 32157 with screw terminal @ 19$/cell

Thoughts?



LiFePO4 is the "winner" for me, safety reasons regarding puncture...


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## Karter2 (Nov 17, 2011)

h0tr0d said:


> Just received a quote 90 cells A123 32157 with screw terminal @ 19$/cell
> 
> Thoughts?...


 Im thinking $1700 and 50lb pack. !


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## GeoMetric (Aug 13, 2010)

h0tr0d said:


> Thank all for the tips.
> 
> Just received a quote 90 cells A123 32157 with screw terminal @ 19$/cell
> 
> ...


You must be very careful, the ONLY distributor to the public for A123 cells is/was Mavizen. All other outlets to buy A123 are fake or damaged goods. Here is their link:

http://www.mavizen.com/


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## h0tr0d (Mar 26, 2012)

GeoMetric said:


> You must be very careful, the ONLY distributor to the public for A123 cells is/was Mavizen. All other outlets to buy A123 are fake or damaged goods. Here is their link:
> 
> http://www.mavizen.com/


ONLY official! @ endless-sphere.com a lot of people bought good quality a123 20ah and other cells... 
a lot of rip-offs also.

OSN has a good reputation on that forum if I read correctly.



> Im thinking $1700 and 50lb pack. !


You and me... I asked for 70 cells (30S2P + 10 extra just in case...)
Your Nano-tech suggestion was, for a very long time, my first choice but the calendar life, puncture safety and flames and puffing for no reason put me off... 
Just because I'm selling the vehicle afterwards! If it was for me to ride, hell yeah!!! 

*Whats the internal resistance of A123 32157 cells? 2~3mohms?*

*GeoMetric can you measure that?*


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## Brute Force (Aug 28, 2010)

When you place an order these, just keep in mind that A123 does not even acknowledge the existence of the 32157 cells. That said, I'm still very curious about them.


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## Jozzer (Mar 29, 2009)

h0tr0d said:


> ONLY official! @ endless-sphere.com a lot of people bought good quality a123 20ah and other cells...
> a lot of rip-offs also.
> 
> OSN has a good reputation on that forum if I read correctly.
> ...


 DIYGuy on this forum has bought and tested these cells I believe, drop him a PM for more REAL info (he's very helpful).
Not all the grey market A123's are counterfeight/dud cells, some seem perfectly good. I'd be wary of buying the 20AH pouch cells however, we KNOW some of those are bad..


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## agniusm (Apr 30, 2012)

I want to jump in to this discussion about A123 cells. I like 32113 cell as it's most powerful of A123 range but.. I done some primitive maths regarding weight and AMP20M1HD is the lightest of them all.
32157 would come at around 630g for 20AH
32113 at 840g. for 20AH
36650 at 560g. for 20AH
when 20AH AMP20M1HD is at 480g.
From my point of view latest is the best one regarding weight and power.
i played about with them, have a pack in my scooter and 600km down, no problems yet. Here is my approach on termination:








30S1P:









I am purchasing 25 32113 from ONS soon for another scooter project so it will be interesting to see how they perform.
I am also a bit skeptical on 32157 as there is no official info from A123 about them


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## ga2500ev (Apr 20, 2008)

> when 20AH AMP20M1HD is at 480g...


Sorry for the detour, but I have to ask:

Is there any reliable, moderately priced (below $30 USD shipped), source for these cells? It seems like every source that I've seen is either uber-expensive (like $49/cell at abc123rc.com excluding shipping IIRC) or ultra-unreliable (VictPower cast offs with cut or perforated tabs). I've yet to see a happy middle ground.

I look forward to hearing more about cell testing...

ga2500ev


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## agniusm (Apr 30, 2012)

I am ordering soon from ONS power. I did in the past for 10 cells. All good. I haven't heard of bad cells coming from them except one chap bought USA made cells and got Korean ones but they seem to be fine. When buying from them need to specify that you want full tabs, USA made cells, no wrinkles. At the moment they go for 30-32 a piece. On larger quantities possible to get a better deal plus shipping. I would not go to Victpowe. Had 18 dead Korean cells coming from them. Sorted in the end but bad experience all over the place with them.
32113 going for 10-12USD pcs; 32157 - 15-16USD pcs.


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## GeoMetric (Aug 13, 2010)

Buying a battery really depends on your application, if you want a low cost pack built with failed black market cells, then the Chinese A123 rejects are your best choice. You might get some with minor defects or some with a catastrophic failures, I would not recommend. There are many on this board and the Endless Sphere forum that have had to rebuild their pack because they played Russian roulette. Explaining this to some is like talking to a brick wall, so be it. In regards to lipo cells from China, 99% are hand built with no vacuum chamber, that is why the failure rate is over 3%. The only cells I would recommend if I were paying would be:

*A123 (Mavizen Only)
K2 Energy Solutions
CALB
Dow Kokam
LG Chem
GAIA
Saft
EIG
GBS*

If you want to play Russian roulette, here is the game link:
http://www.alibaba.com


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## agniusm (Apr 30, 2012)

GeoMetric said:


> if you want a low cost pack built with failed black market cells, then the Chinese A123 rejects are your best choice. You might get some with minor defects or some with a catastrophic failures, I would not recommend.


This was proven wrong many times with IR, discharge, capacity tests, cycle tests etc.
I dont say they'r all good but mavizen 99USD a piece if purchased up to 100pcs is a load of crap. 
Get real, there is practical proof for that!! Say rejects, perhaps back door at best. I would not be surprised if A123 them selves are behind all back door business shaking off liability.


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## Genius Pooh (Dec 23, 2011)

agniusm said:


> I am ordering soon from ONS power. I did in the past for 10 cells. All good. I haven't heard of bad cells coming from them except one chap bought USA made cells and got Korean ones but they seem to be fine. When buying from them need to specify that you want full tabs, USA made cells, no wrinkles. At the moment they go for 30-32 a piece. On larger quantities possible to get a better deal plus shipping. I would not go to Victpowe. Had 18 dead Korean cells coming from them. Sorted in the end but bad experience all over the place with them.
> 32113 going for 10-12USD pcs; 32157 - 15-16USD pcs.


Do you know about best price for 20ah pouch?

mine is ebay's price 25$ as volume or outside of ebay


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## Genius Pooh (Dec 23, 2011)

GeoMetric said:


> They have been tested and proven, here is addition info:
> *26650P*
> 
> When high power is essential, this battery delivers with a burst of *150A *from a single cell.
> ...



Can you tell me price? 

It's my major point


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## h0tr0d (Mar 26, 2012)

GeoMetric said:


> Buying a battery really depends on your application, if you want a low cost pack built with failed black market cells, then the Chinese A123 rejects are your best choice. You might get some with minor defects or some with a catastrophic failures, I would not recommend. There are many on this board and the Endless Sphere forum that have had to rebuild their pack because they played Russian roulette. Explaining this to some is like talking to a brick wall, so be it. In regards to lipo cells from China, 99% are hand built with no vacuum chamber, that is why the failure rate is over 3%. The only cells I would recommend if I were paying would be:
> 
> *A123 (Mavizen Only)*
> *K2 Energy Solutions*
> ...


Where to buy Saft cells?

Can you post some links to sellers of those cells?

Thanks


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## h0tr0d (Mar 26, 2012)

agniusm said:


> I am ordering soon from ONS power. *32157 - 15-16USD pcs*.


For how many cells if I may ask. Shipping included?


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## major (Apr 4, 2008)

This thread was about testing the cells, but WTH 

So I've been screwing around with my load bank and went to straight contactor/resistor. Won't be any current regulation. And the resistor is actually 15 inches of 4/0 welding cable. But I have some other cable in the loop to connect the cell and an instrument shunt. I don't have my instruments set up to record data yet. Just testing with a voltmeter and clamp ammeter.

On a single A123 32157 cell I saw over 300A, like 340, only for a few seconds. Voltage was over 2.0. Like I said, just set-up, not real hard data...........yet


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## h0tr0d (Mar 26, 2012)

major said:


> This thread was about testing the cells, but WTH
> 
> So I've been screwing around with my load bank and went to straight contactor/resistor. Won't be any current regulation. And the resistor is actually 15 inches of 4/0 welding cable. But I have some other cable in the loop to connect the cell and an instrument shunt. I don't have my instruments set up to record data yet. Just testing with a voltmeter and clamp ammeter.
> 
> On a single A123 32157 cell I saw over 300A, like 340, only for a few seconds. Voltage was over 2.0. Like I said, just set-up, not real hard data...........yet


Sorry Major, you are right. Too much off topic.

*5 mohm resistance then?*

*(3.65-2V)/340A= ~5*


.


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## major (Apr 4, 2008)

h0tr0d said:


> Sorry Major, you are right. Too much off topic.
> 
> *5 mohm resistance then?*
> 
> *(3.65-2V)/340A= ~5*


Nah, it was no 3.65, more like 3.3 something. And was higher than 2.0 at the start. Don't use that data. I'll post up more when I get computer hooked up to the test.

edit: Fresh off the charger....see the next post.


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## major (Apr 4, 2008)

Here is a recorded test.










My current transformer maxed out at 375A (10V for its output), so the initial peak current is a bit higher. Also note that cell voltage drops to just about one half which indicates this is at peak power out of this cell. I think it ran for about 35 seconds. Nice long pulse  The little sucker was pretty warm. About 160ºF. And it seemed consistent across the cell body. Terminals were actually cooler, about 100º.

edit: I figure this is about a 47C rate.


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## Karter2 (Nov 17, 2011)

Thanks for taking the time & trouble to generate and post that info.
Impressive results, i assume you stopped the test due to cell temperature ?.. since it seems it was still pumping out the amps !


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## major (Apr 4, 2008)

Karter2 said:


> Impressive results, i assume you stopped the test due to cell temperature ?


Yeah, I hate it when they have to evacuate the building on my account  I didn't have this one in a hood or Liposack or nuthin'. Just laying on a wood bench with a steel trash can next to it just in case. But when I saw temperature reach 150ºF, I figured I made my point.


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## Jozzer (Mar 29, 2009)

major said:


> Yeah, I hate it when they have to evacuate the building on my account  I didn't have this one in a hood or Liposack or nuthin'. Just laying on a wood bench with a steel trash can next to it just in case. But when I saw temperature reach 150ºF, I figured I made my point.


 Nice test Major. They really are amazing cells. Like to see the same test applied to a K2..


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## Genius Pooh (Dec 23, 2011)

major said:


> Here is a recorded test.
> 
> 
> 
> ...



Great one.. I worry it's life cycle.. Is this cell can endure more than 200 cycle at 20-30c rate?

Is this too much hope?


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## Jozzer (Mar 29, 2009)

Genius Pooh said:


> Great one.. I worry it's life cycle.. Is this cell can endure more than 200 cycle at 20-30c rate?
> 
> Is this too much hope?


I used these for a couple of years in an ebike that pulled 80A - I had a 1p 100v pack, and would blast full throttle all the way to work (1/4 mile away) every day, recharge at work (at 5C), then do the same on the way home - so 2 cycles a day, 5 days a week for 2 years (or more). At the end of the 2 years I upgraded to LiPo, but the A123's still delivered over 2Ah each, and could still deliver full power with no more sag than when new - in fact it seemed that IR went down with abuse rather than up!
So, 5 days a week (more like 7 in reality!), twice a day for 2 years = 1000 cycles!

Edited to add - I've still got these cells - they have been sitting on the shelf since 2010 and still read 3.3v and give close to 2Ah..


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## h0tr0d (Mar 26, 2012)

Some calcs from Major's test:

At approx 46C discharge (!!!)
[email protected]= 4.13 mohm
[email protected]= 5.76 mohm
[email protected]= 4.86 mohm

Not bad at all!!!

*Major could you repeat the test @ 260A? *
That's 35C, the datasheet maximum of these cells.

Thanks


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## Yabert (Feb 7, 2010)

HotRod, it's more like that:

3.2v - 1.55 = 1.65/375 = 4.4 mohm
3.2v - 1.75 = 1.45/360 = 4 mohm
3.2v - 1.9 = 1.3/330 = 4mohm


or in fact, around 3-4 mohm after verifying the Major graph's.


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## h0tr0d (Mar 26, 2012)

Yabert said:


> HotRod, it's more like that:
> 
> 3.2v - 1.55 = 1.65/375 = 4.4 mohm
> 3.2v - 1.75 = 1.45/360 = 4 mohm
> 3.2v - 1.9 = 1.3/330 = 4mohm


I used 3.65V (Start voltage in test) - 2.1V = 1.55V @ 375A

To me, it makes a lot more sense than using the theoretical value of 3.2V...


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## Yabert (Feb 7, 2010)

h0tr0d said:


> To me, it makes a lot more sense than using the theoretical value of 3.2V...


But not for the rest of the planet beacause full charge cell drop at 3.3v-3.40v after few hours disconnected of the charger....
And often at 3.2v-3.3v under light load.

Just a example:
You cruise with your hot rod at low speed and all your cells will be around 3.2v (because they don't are fresh of the charger). To show off, you floor the accelerator and the tires smoke a lot.... during this time your cells hit 2v. The internel impedance will be 3.2v - 1.2v / XXXX Amps.


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## major (Apr 4, 2008)

h0tr0d said:


> Some calcs from Major's test:
> 
> At approx 46C discharge (!!!)
> [email protected]= 4.13 mohm
> ...


To calculate the internal resistance you need to use the difference in voltage from two different current values. So, at approx 106 seconds there is a step (almost) change in voltage as the current goes from 360A to zero. The cell voltage goes from 1.9V to 3.13V. A difference of 1.23V. 1.23V / 360A = 0.0034Ω = 3.4mΩ.

Sample rate is 4 Hz on my test and the plot is not smoothed further. 

As far as running tests at constant current, I cannot because I had to remove my regulator to get the low resistance for the low cell voltage/high current tests. This also makes it difficult to zoom in on particular current values at which to run a test. It involves changing cable lengths basically. I might rerun the A123 test if I have a slightly higher R load set up.

First I need to up the CT to run some higher current test on a slightly larger cell


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## major (Apr 4, 2008)

h0tr0d said:


> I used 3.65V (Start voltage in test) - 2.1V = 1.55V @ 375A


The 375A value is false due to limitation of my current sensor. Actual current was higher than 375 but I could not record it.

Always use actual values; never spec sheets when calculating this 

Also, the internal resistance is temperature dependent so using a point at the end of my test is a little optimistic.


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## Yabert (Feb 7, 2010)

major said:


> Also, the internal resistance is temperature dependent so using a point at the end of my test is a little optimistic.


Hahaha!! True, running the pack at 150°F (65°C) isn't quite practical!!

By the way, thank for the tests Major.


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## h0tr0d (Mar 26, 2012)

Yabert said:


> But not for the rest of the planet beacause full charge cell drop at 3.3v-3.40v after few hours disconnected of the charger....
> And often at 3.2v-3.3v under light load.
> 
> Just a example:
> You cruise with your hot rod at low speed and all your cells will be around 3.2v (because they don't are fresh of the charger). To show off, you floor the accelerator and the tires smoke a lot.... during this time your cells hit 2v. The internel impedance will be 3.2v - 1.2v / XXXX Amps.


I'm analysing a factual test not your hypothetical example.
Using the initial 3.65V might be excessive, I'll give you that, but at least the 3.4V measured at the end of the test (although 3.5V, "mean" value during *this test*, would be more appropriate...).

So, using 3.5V:
3.73 mohm
5.3 mohm
4.4 mohm 
Mean = 4.5 mohm (not bad...)


For my application, a 30S2P Headway 38120P high power, would probably be good enough and cheaper.

I've searched a bit but can't seem to find recent discharge test for HeadWays here, can anyone point me to them?


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## Genius Pooh (Dec 23, 2011)

Jozzer said:


> I used these for a couple of years in an ebike that pulled 80A - I had a 1p 100v pack, and would blast full throttle all the way to work (1/4 mile away) every day, recharge at work (at 5C), then do the same on the way home - so 2 cycles a day, 5 days a week for 2 years (or more). At the end of the 2 years I upgraded to LiPo, but the A123's still delivered over 2Ah each, and could still deliver full power with no more sag than when new - in fact it seemed that IR went down with abuse rather than up!
> So, 5 days a week (more like 7 in reality!), twice a day for 2 years = 1000 cycles!
> 
> Edited to add - I've still got these cells - they have been sitting on the shelf since 2010 and still read 3.3v and give close to 2Ah..


Thanks I must book mark your answer thanks so much!


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## JRP3 (Mar 7, 2008)

Jozzer said:


> This is actually a thread about A123 - YOU were the one who hijacked it to offer a product from your sponsors (despite the fact you've not tried them yet!).


Some things never change


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## kennybobby (Aug 10, 2012)

And this so-called and obsessed over "internal resistance" is important to know for what and why?


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## major (Apr 4, 2008)

kennybobby said:


> And this so-called and obsessed over "internal resistance" is important to know for what and why?


The internal resistance of the battery determines the peak power, sag, efficiency and heat.


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## GerhardRP (Nov 17, 2009)

major said:


> Here is a recorded test.
> <cut image>
> My current transformer maxed out at 375A (10V for its output), so the initial peak current is a bit higher. Also note that cell voltage drops to just about one half which indicates this is at peak power out of this cell. I think it ran for about 35 seconds. Nice long pulse  The little sucker was pretty warm. About 160ºF. And it seemed consistent across the cell body. Terminals were actually cooler, about 100º.
> 
> edit: I figure this is about a 47C rate.


Hi Major, nice work.
It is interesting to me that the current draw and time are about the same that would have resulted in my proposed standard test: http://www.diyelectriccar.com/forums/showthread.php/grp-battery-test-procedure-83565.html
Briefly, two charged cells are placed in series with a parallel pair of discharged cells in the reverse direction. This results in a circuit with nominally one cell's voltage driving current through a resistance 2.5 times the internal resistance of one cell.
I=3.3V/(2.5*.0034 Ohms) = 388 Amps
The measured temperature rise, [assuming a 70F start] is 50C as I suggested. Only difference is monitoring the body, not terminals.
Gerhard


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## major (Apr 4, 2008)

GerhardRP said:


> Hi Major, nice work.
> It is interesting to me that the current draw and time are about the same that would have resulted in my proposed standard test: http://www.diyelectriccar.com/forums/showthread.php/grp-battery-test-procedure-83565.html
> Briefly, two charged cells are placed in series with a parallel pair of discharged cells in the reverse direction. This results in a circuit with nominally one cell's voltage driving current through a resistance 2.5 times the internal resistance of one cell.
> I=3.3V/(2.5*.0034 Ohms) = 388 Amps
> ...


I saw that RP, just don't understand it  The two series charged cells' voltage would add (3.3 + 3.3 = 6.6) and then have the discharged cell voltage as load (2.5) so resulting voltage for current calc is 4.1V at the start but decreases as the SOC changes over time. 

So I don't see a resulting figure of merit which is useful as the cell voltage w.r.t SOC is so different for various cell makes.

The other problem I see is keeping 3 or 4 cells healthy and in the proper SOC for these tests. It is hard enough with a single cell or battery of multiple cells.

I am old school and like the constant current tests but have to settle for constant resistance test when working with these low V high I cases.


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## GerhardRP (Nov 17, 2009)

major said:


> I saw that RP, just don't understand it  The two series charged cells' voltage would add (3.3 + 3.3 = 6.6) and then have the discharged cell voltage as load (2.5) so resulting voltage for current calc is 4.1V at the start but decreases as the SOC changes over time.


Actually, I bring the discharged cells up 10 % to get them on the flat part of the Open circuit voltage vs. SOC curve. The charged ones are also brought down 10% to get away from surface charges, etc. Modern cells have nearly constant OCV there.


major said:


> So I don't see a resulting figure of merit which is useful as the cell voltage w.r.t SOC is so different for various cell makes.


What we get is a standard pulse current that is only slightly smaller that the maximum power point current and also the time that the cell can deliver that current and stay at a safe temperature. The standardized procedure allows inter-comparison of cells.


major said:


> The other problem I see is keeping 3 or 4 cells healthy and in the proper SOC for these tests. It is hard enough with a single cell or battery of multiple cells.
> 
> I am old school and like the constant current tests but have to settle for constant resistance test when working with these low V high I cases.


Well, I am trading the care and feeding of high power current sources and power dumps for four batteries and simple instrumentation that belongs in every EV-DIY garage. Besides. you don't have to know anything about the cells before you start.
Gerhard


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## major (Apr 4, 2008)

GerhardRP said:


> Modern cells have nearly constant OCV there.


Not true, sorry. Maybe for A123 or some others. But I see more than a few LiPoly type cells having goodly slopes w.r.t. SOC. And some of those are on Davide's cart. 

The cells I am presently testing have this slope so I'll continue with my constant resistance tests. And I only have 2 of the A123 single cells, so can't run your test with those.


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## h0tr0d (Mar 26, 2012)

agniusm said:


> I am ordering soon from ONS power.
> 32157 - 15-16USD pcs.


That 15-16USD price per cell is for many cells? Cindy is asking a bit more at the moment...


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