# a123rc-test



## Rational (Nov 26, 2011)

sokon said:


> Dear all,
> I just took some risk and ordered 34 a123 20Ah cells for 1400$ from a123rc and payed by bank transfer. I`d like to share the outcome of this venture... I hope the best^^


So finally somebody can measure cell to cell variation in Ah capacity for cells at this rating. This tolerance limit info can be used in declaring a battery good or bad.


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## sokon (Sep 15, 2011)

It will be a pleasure for me to provide you with my data, you just have to tell me how to measure everything and what equippement that I need. (I am more the theory guy^^)


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## Rational (Nov 26, 2011)

Probably best to rent an adjustable constant current sink/load so you can measure capacity, I guess at whatever rate you're going to be draining them.

Next best is a variable resistor load of at least 6 watts/cell. Then you or 'your helper' get to periodically vary the resistance for 20 hours or less to simulate constant current loading, more frequently at the end.
I once made a small version of one of these
http://en.wikipedia.org/wiki/Liquid_rheostat
and with 3v there is virtually no shock danger.

Or use a vehicle and an amps/volts monitoring circuit on each cell.

You have a link to the maker's specs and curves? For that many bucks they owe you several pages and maybe some Application Notes. And since you're a serious buyer I'd hope they gave you a better-than-average batch of cells.


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## sokon (Sep 15, 2011)

thanks for your reply,

some years ago I worked at a robotics lab (unfortunately for my EV project, I was the theory guy there). I still know the people there and we are on friendly terms. There is a lot of equippment lying around which I am sure I could borrow if I ask, I only have to know how it looks and how to use it..


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## sokon (Sep 15, 2011)

Update: a123rc has confirmed my payment.


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## DIYguy (Sep 18, 2008)

sokon said:


> Dear all,
> I just took some risk and ordered 34 a123 20Ah cells for 1400$ from a123rc and payed by bank transfer. I`d like to share the outcome of this venture... I hope the best^^


You shouldn't have any trouble with A123RC. I have bought from them before with no issues.


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## Rational (Nov 26, 2011)

sokon said:


> thanks for your reply,


You're welcome. Good luck with your batteries.


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## IamIan (Mar 29, 2009)

Rational said:


> Probably best to rent an adjustable constant current sink/load so you can measure capacity, I guess at whatever rate you're going to be draining them.
> 
> Next best is a variable resistor load of at least 6 watts/cell. Then you or 'your helper' get to periodically vary the resistance for 20 hours or less to simulate constant current loading, more frequently at the end.
> I once made a small version of one of these
> ...


A PowerLab8 might be easier ... it will do all the adjusting for you ... and log everything for you ... It can do both charge and discharge... or programmable cycle testing.

There are other units as well ... of course from other companies ... depending on the test specs desired and budget.


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## Batter (Nov 11, 2011)

sokon said:


> Dear all,
> I just took some risk and ordered 34 a123 20Ah cells for 1400$ from a123rc and payed by bank transfer. I`d like to share the outcome of this venture... I hope the best^^


You really took a risk 'cause you payed it by bank transfer.Good luck, but you said that you bought them from A123rc.Anyway after you receive the cells keep me informed. Thank you !


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## Batter (Nov 11, 2011)

sokon said:


> Dear all,
> I just took some risk and ordered 34 a123 20Ah cells for 1400$ from a123rc and payed by bank transfer. I`d like to share the outcome of this venture... I hope the best^^


 34 a123 20Ah just cost $1400, free shipping?
If so , I think there is not much to expect high quality cells with this price.Small errors may exist. As you know the good quality A123 batteries are expensive. Good luck! But the battery from A123 is good.


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## sokon (Sep 15, 2011)

> 34 a123 20Ah just cost $1400, free shipping?


yep, that is why I just had to try it^^




> I think there is not much to expect high quality cells with this price


well, I do expect what a123rc claims to deliver and that is 34x 20Ah a123 cells. I dont think that 40$ is an unrealistic price (we will see by the outcome of this venture^^).
After all, I think that a123 is using this channels to sell of some of their cells without taking any risk or responsability.


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## sokon (Sep 15, 2011)

UPDATE: Received tracking number. ETA = 20. December 2011


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## Batter (Nov 11, 2011)

sokon said:


> yep, that is why I just had to try it^^
> 
> 
> 
> ...


 OK, keep me informed. In my mind, the small errors of these cells are understandable.As you know,the genuine A123 cells are very expensive.


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## sokon (Sep 15, 2011)

Hello Batter,

What do you mean by "genuine"? I think it is hard to believe that somebody has set up a production line to manufacture cells that just look like 20Ah a123 cells. A scenario that imho is much more realistic is the they are cells that where produced by a123 (and thus are "genuine" as I understand the term) but for some reason did not go the official way to the customers. I see several reasons why such cells could end up in the "grey market"

1. They dont meet specs or where used for testing. They where sold as junk and then introduced to the market (e.g. cells with tabs cut off)

2. Some people that work in factories actually steal some cells and sell them (that seems a bit unrealistic).

3. A123 wants to sell cells but doesnt want to be liable if something goes wrong with them (e.g. fire, electric accidents, etc) when handled by non professionals. Further they dont want to risk the reputation of their chemistry as to be safe because some amateurs stress the cells over the limit or dont use bms etc. The problem is that if something goes wrong, that could harm some big business with oems.
A solution is to just sell the cells as junk for say 20$/piece (which would most likely still pay off for a123) and then anounce that cells that are bought over the net are dangerous/rejects and not for actual use.. 

Of course this is all SPECULATION. I dont believe anything of that IS true, I just consider it possible until somebody gives me a reason not to think that anymore..


best,
sokon


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## drgrieve (Apr 14, 2011)

I think what he was meaning is that the cells might have a slightly reduced capacity or more than normal resistance.

But then you may be lucky and they are perfect.

Proof will be in the testing.


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## rwaudio (May 22, 2008)

I purchased one 20ah cell from A123rc and it tested well, met all specs except for capacity as it was about 18.6ah. I have some (few hundred) 20ah a123 cells from a different source and although they were much cheaper they are slightly lower capacity. Average is more like 18ah, most have good IR but there are a few that will only make it into my 12v battery due to low capacity/ high IR. I'm a stereo guy so I still need a good 12v system and the rejects should work well for that purpose.


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## frodus (Apr 12, 2008)

how many amps was the capacity test? 20A?


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## phairno (Dec 16, 2011)

Batter said:


> OK, keep me informed. In my mind, the small errors of these cells are understandable.As you know,the genuine A123 cells are very expensive.


 Have you ever bought cells from A123rc? I'm a regular buyers from that site, the cells I received are good, so in your mind what is the genuine A123 batteries? Or just let's wait for the results.


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## frodus (Apr 12, 2008)

phairno said:


> Have you ever bought cells from A123rc? I'm a regular buyers from that site, the cells I received are good, so in your mind what is the genuine A123 batteries? Or just let's wait for the results.


Got any pictures of your cells in your projects? A blog?

Excuse my speticism, but you only have 2 posts and you could just as easily be A123rc.....posting under a different name.


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## phairno (Dec 16, 2011)

frodus said:


> Got any pictures of your cells in your projects? A blog?
> 
> Excuse my speticism, but you only have 2 posts and you could just as easily be A123rc.....posting under a different name.


It doesn't matter, I see many sockpuppet in forums.First I just became a member of this forum several days ago due to sokon's link in endless sphere, I really want to know what would happen to his cells from A123rc,
the following are the pictures of my cells, I built it by myself.


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## sokon (Sep 15, 2011)

UPDATE: It looks like christmas is on 20.12. for me this year 

cells arrived and the first voltage test looks good! Here are the readouts:

https://docs.google.com/spreadsheet/ccc?key=0AhtFYXutdAAHdEZiT0NtM1pqVHNMZ1Vrb19SWFdIOHc

capacity test will follow. (after thursday, until then I have to prep. a talk , but then it is diyev-time).


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## sokon (Sep 15, 2011)

So, I have a question. Since I bought the cells earlier than I had planned to, I dont have a charger yet. How much do I have to hurry to charge them in order not to let them over discharge (I hope that the self discharge rate is as low as this might be not something that I have to care for in the next couple of days).


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## frodus (Apr 12, 2008)

They'll hold their charge for a while, lifepo4 has low self discharge.... cells I charged 6 months ago show no signs of discharge (that I can tell).

How do you plan on testing capacity? Do you have a discharger?

Might consider getting a powerlab, it's got a charger and discharger built into one.


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## sokon (Sep 15, 2011)

> How do you plan on testing capacity? Do you have a discharger?


good question. I havent thought about it much yet, my naive approach would be to get (if I can find something like that) a voltmeter and amperimeter that can talk to my pc, then attach the battery to a resistor, that I chose so that @3V, the current is 20A (i.e. 150mOhm). After that I will let the pc integrate the voltage times current over time. I will manually stop the procedure (by disconnecting the battery) when the voltage readout is 2.5v or below.

However, if there is an easier way to do that, I am (more than) happy to hear!


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## DaveAK (Jun 28, 2009)

sokon said:


> good question. I havent thought about it much yet, my naive approach would be to get (if I can find something like that) a voltmeter and amperimeter that can talk to my pc, then attach the battery to a resistor, that I chose so that @3V, the current is 20A (i.e. 150mOhm). After that I will let the pc integrate the voltage times current over time. I will manually stop the procedure (by disconnecting the battery) when the voltage readout is 2.5v or below.
> 
> However, if there is an easier way to do that, I am (more than) happy to hear!


Get a CBAIII from West Mountain Radio.

http://www.westmountainradio.com/product_info.php?products_id=cba3


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## sokon (Sep 15, 2011)

> Get a CBAIII from West Mountain Radio.


well, ok that solves all my probs at once  (altough it is a little expensive).
Thanks for the link.


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## frodus (Apr 12, 2008)

Dammit dave! beat me to it! haha

I second that. By the time you get a decent power resistor (something larger than 100W), a data logger, shunt resistor and software and set up a test bench, you'll likely spend more money and time than just buying a CBA-II. They're about $150 if I recall correctly. They do discharge only, but they do monitor charging.

That, or you could get a powerlab8, like I mentioned before. It's a charger and discharger. Both are USB connected and log a discharge. The powerlab8 can do cycle testing though, but it's quite a bit more expensive.

Another thing, when doing a manual discharge like that, you really want the LVC to happen automatically.... i.e. the load needs to be removed at or before 2.5V. It's a VERY steep curve for batteries, and just relying on your reflexes and not forgetting.... well, lets just say I've overdischarged a couple.

My equipment is a CBA-II and an add-on amplifier to do up to 150A. I recently sold the CBA because I have a computerized setup now. I would highly recommend either a CBA-II or CBA-III to someone just getting into batteries. It's a pretty safe and easy way to do capacity testing. It gives pretty accurate numbers for everything, and its simple to setup.


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## dladd (Jun 1, 2011)

frodus said:


> That, or you could get a powerlab8, like I mentioned before. It's a charger and discharger. Both are USB connected and log a discharge. The powerlab8 can do cycle testing though, but it's quite a bit more expensive.


fwiw, the powerlab 6 appears to be newly released, and for single cell purposes does the same thing as the powerlab 8 for under $200. If powered from a 12v battery, it will charge/discharge at 40a, do cycle tests, chart AH, and measure IR. Pretty slick! I've not used one so I'm just going from the literature on their website.


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## Nuts&Volts (Dec 20, 2011)

I picked up a PL8 combo. Used it to cycle a LiPo a few times and am now using it to balance charge a large LiPo pack. It works very well and seems super reliable. I plan to do some long term cycle testing with it hooked up to a PC. Just started learning the software, but overall it is a great tool with plenty of settings to mess with. I can literally create a charging preset by changing over 50 individual parameters.

So if you need some to test batteries with now and in the next ten years then the PL8 from FMA is a great choice. Cycling, capacity testing, internal resistance testing, balancing, and basic charging for batteries ranging from 1mAh to 60Ah are possible. 

Looking forward to seeing your results of these A123 batteries


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## DIYguy (Sep 18, 2008)

Nuts&Volts said:


> Cycling, capacity testing, internal resistance testing, balancing, and basic charging for batteries ranging from 1mAh to 60Ah are possible.


 Just for the record, it's not limited to 60ah batteries. You can do any size you want....


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## Nuts&Volts (Dec 20, 2011)

DIYguy said:


> Just for the record, it's not limited to 60ah batteries. You can do any size you want....


Thanks, I didnt want to claim more than I thought it could do. I wasn't sure what the max discharge current (in regen mode) of the unit. I also was assuming a least a 1C discharge. >60A seems like a lot for the PL8, but I haven't used it enough to know


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## DIYguy (Sep 18, 2008)

Oh ur right about the current. . It won't do 60 amps. 40 amps is max charge and discharge current. Capacity, or duration of charge is a different matter. 

You can generate a "Fuel table", which is basically a set of custom parameters, for most any battery.


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## sokon (Sep 15, 2011)

hi all,

thanks for the links.

I am about to buy either a CBAIII or a pwrlab6. As I will use them just for testing the cells I bought, I want to spend as little money as possible. In order to use the CBAIII, I additionally need a single cell charger (right?). Unfortunately for the pwrlab cost an additional 50$ for shipping which I think is rather expensive (after all I didnt want to spend worth 5cells just to test them). All in all I see it like that:

CBA: 150$+whatever a single cell charger costs+shipping
pwrlb6: 160$+50$shiping+pwr supply(maybe I can borrow one from a friends lab)

Is there anything I am missing.

If the pwrlab8 could also be used to charge the finished pack (34s1p), then this would justify the price and I might just buy it.

rgrds


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## DIYguy (Sep 18, 2008)

sokon said:


> Is there anything I am missing.
> 
> If the pwrlab8 could also be used to charge the finished pack (34s1p), then this would justify the price and I might just buy it.
> 
> rgrds


It's called a PL8 (or PL6) because it can do up to 8 (or 6) series connected cells. 
So, no, you can't do 34s-1P. You can do, however, virtually any number in parallel as long as you don't exceed the 8 (or 6) series derivitive.


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## frodus (Apr 12, 2008)

Exactly, not all at once. It could be used to charge a 34s1p pack, in groups of 6 or 8 to equalize all cells before you use it the first time.

After that, I'd use a bulk charger, or something programmed for 34 cells in series. This is not a bulk charger that you could use for voltage that high.


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## Nuts&Volts (Dec 20, 2011)

Where are you trying to order from that costs $50 to ship? i guess maybe you are located internationally..

Newegg/ProgressiveRC have it for $175 plus free shipping
http://www.newegg.com/Product/Produ...adio+Controlled-_-FMA+Direct-_-9SIA0UF0777006

OR you can get it here http://www.revolectrix.com/ and save 10% ( I think you need to phone in your order to get the discount).


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## sokon (Sep 15, 2011)

I was about to order from revolectrix.com


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## frodus (Apr 12, 2008)

shipping to where though?


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## sokon (Sep 15, 2011)

zürich, switzerland


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## rwaudio (May 22, 2008)

sokon said:


> zürich, switzerland


Are you ordering from the USA site or the international site? I just ordered the PL6 from the international site and shipping was $35 to Canada.


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## sokon (Sep 15, 2011)

UPDATE: First cell tested.

Capacity: 18115mAh @ 5A dischatge rate.

Notes: Cut off voltage was set to 3V. The battery was settling to 3.15V after the discharge with no load. So I think the 18115mAh are just fine!

IR: 15mOhm

Notes: I used a those: http://en.wikipedia.org/wiki/File:Aligator_clip_442.jpg
to attach the battery to the charger, due to small contact area, this might have some influence to the IR test?

General Notes: I used a Graupner ultra trio plus 16 (thst I can borrow from a friend ) to perform the test.

PS: Has anybody a spec sheet from a123 for these cells. It used to be available from the a123 website but it is not anymore


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## Nuts&Volts (Dec 20, 2011)

18.1Ah is pretty good with a 3V cutoff. But you are only testing at 5A (0.25C). 

A test at 1C and with a 2.5V cutoff would be easier to compare to other cell data...

Try this link http://www.a123systems.com/Collateral/Documents/English-US/A123 Systems AMP20 Data Sheet.pdf


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## steven4601 (Nov 11, 2010)

Hello,
Are you certain you have measured the resistance correctly...? 15mOhm is rather high for a 20Ah cell. To measure the resistance with an Icharger or derevative you'll need to use a 4 wire measurement. 2 thick wires that go to the charge connectors, and two (smaller wires) that go to your balancing port. With 4-wires it allows to see the voltage of the cell rather than the voltage drop over the charger (current carrying) wires.


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## sokon (Sep 15, 2011)

> Are you certain you have measured the resistance correctly...?


No, indeed I think that the IR number that the charger provides is rather useless. 
1. there are only two cables.
2. the clips with which the charger is attached to the battery has minimal contact surface (might make for some resistance by itself).

If you can tell me a method to measure IR without a charger, I would apply it and submit the results.

Best,
sokon


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## LithiumaniacsEVRacing (Oct 9, 2010)

sokon said:


> Hello Batter,
> 
> What do you mean by "genuine"? I think it is hard to believe that somebody has set up a production line to manufacture cells that just look like 20Ah a123 cells. A scenario that imho is much more realistic is the they are cells that where produced by a123 (and thus are "genuine" as I understand the term) but for some reason did not go the official way to the customers. I see several reasons why such cells could end up in the "grey market"
> 
> ...


I know for a FACT that these cells are rejects from A123, they were produced in South Korea for A123, but were removed from inventory because of defects. Since the split of A123 from RC123, they Korean company is now selling the rejects left in stock. Good Luck!


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## LithiumaniacsEVRacing (Oct 9, 2010)

frodus said:


> Got any pictures of your cells in your projects? A blog?
> 
> Excuse my speticism, but you only have 2 posts and you could just as easily be A123rc.....posting under a different name.


I agree, it is obvious A123rc is here trying to sell leftover rejected stock.


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## rwaudio (May 22, 2008)

LithiumaniacsEVRacing said:


> I agree, it is obvious A123rc is here trying to sell leftover rejected stock.


Hi Ron,

To add to your point, I doubt A123RC was ever directly connected to A123systems. It's simply a chinese company using A123's name to sell batteries. They got their hands on some cells and away they went.

I bought some of the 18650's from A123RC and they are not A123's, they do perform quite well and will do 30-40C peaks easily but based on heat I would peg the continuous current closer to 20 or 25C. (maybe I'm not pushing them hard enough, they do get hot)

I also bought a 20ah cell from them and it had the "made in Korea" badge and worked very well, came in just over 19ah and easily put out 400A with expected sag and heating. (I couldn't test any higher)

I'm not sure why you are so interested in pointing out that these cells are rejects, I think we all know that they have questionable origins and should be considered grey market cells of unknown origin. You have no proof that they truly rejects, (I'm not saying they aren't) but A123 does have a manufacturing plant in Korea, that is public knowledge. 

Are you worried about these cells stealing sales from your authentic high C racing cells? If so I think you are mistaken, your cells are Li-Po and I don't think very many people are willing to put Li-Po in a street car (I personally wouldn't). That said, people who are serious about racing want something that works, so I doubt a serious racer would go for these questionable A123 cells (unless they are on a seriously tight budget and then I doubt they would be in the market for your cells either)

If I were you I would consider the availability of these cells a silent blessing. They are similar enough to your cells and widely available for normal cars and bikes that you may be able to benefit from a new connection method or pack design that would make it easier for your customers to actually use your cells.

If you want to go after the mainstream market then have your battery company come up with a LiFePO4 cell that can do a 15 or 20C continuous and 30C peak in a 15-30ah pouch at a fair price. (higher than these grey market a123's but lower than your racing cells).

Just my thoughts, and Ron please take this as constructive input I'm not trying to bash you in any way, just trying to help.


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## LithiumaniacsEVRacing (Oct 9, 2010)

rwaudio said:


> Hi Ron,
> 
> To add to your point, I doubt A123RC was ever directly connected to A123systems. It's simply a chinese company using A123's name to sell batteries. They got their hands on some cells and away they went.
> 
> ...


RW,

I take no offense to your post at all, I welcome it. I have some info (because I have battery connections in China and South Korea). The cells you guys are buying from A123rc are not Chinese copies, they are inventory left behind by A123 USA. When A123 USA was partnered with A123rc of South Korea they shared inventory. While producing their pouch cells, they had a less than 1% failure rate, but the failed cells remained in the hands of A123rc. Now because A123rc has no connection to A123 USA, they are unloading every cell they have, good or bad. Once all cells are sold, I am sure A123rc will change name and move on. Now this info relates to the pouch cell only. South Korea cannot sell A123 cells built by a Chinese company, and have the marking of A123, they would get sued. 

Now, if your source to buy A123 pouch cells is NOT A123rc, then they are most likely Chinese copies. The problem with rejects or copies is you will not know how bad the cell is until many many cycles later.

These cells are in a different market than our racing Haiyin cells, so I am not worried about losing business, our customers need smaller more powerful cells. The larger AH cells carry more density, great for EV conversions.

GLTA!


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## sokon (Sep 15, 2011)

> The problem with rejects or copies is you will not know how bad the cell is until many many cycles later.


this makes it sound as if it is more of a problem the later u notice that ur cell is bad. In fact it is right the other way around: It is less of a problem the later u notice^^



> I know for a FACT that these cells are rejects from A123, they were produced in South Korea for A123,...


most (not all) of them have "made in usa" printed on them..


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## sokon (Sep 15, 2011)

Final update: 

1. all cells have been tested for capacity. Average capacity is 19.214Ah. For details please check https://docs.google.com/spreadsheet/ccc?key=0AhtFYXutdAAHdEZiT0NtM1pqVHNMZ1Vrb19SWFdIOHc&pli=1#gid=0

2. the internal resistance measurements I posted earlier, are flawed (as I thought), the a123rc cells give the same IR results as some cells I have that originate (not directly) from cell_man (good cells I suppose). 

3. I am happy with the cells, even if they are cheaper (32$) on a123rc now )


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## stone3333 (Feb 15, 2012)

Those A123 for $31.99 each is not cheap, I got mine for $19.48 plus shipping & handling

http://www.diyelectriccar.com/forums/showthread.php/making-a123-li-ion-battery-48v-69773.html


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## sokon (Sep 15, 2011)

well, mine have tabs^^

with those "tabs" it will be difficult to make a pack that is good for high current. Using those cells only for low current applications somehow defeats the purpose of a123 cells.

just my .5$


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