A123 ANR26650M1A Questions!

I've purchased a pack of 96 A123 cells, disassembled it, and began selling them, but one buyer has complained that when he charged four cells in series to 12v, (3.25v each, hopefully) the cells only put out 10 amps for 2 minutes before dropping to 2 volts.

My concern was that the cells were so low before he started the test. In the A123 datasheets, 3.25v seems nearly empty. I've asked that he charge them to 3.6-3.65v and get back to me with another test.

What do you guys think? can anyone with any of these cells chime in? these have sat unused for about a year, but they are all holding 3.2-3.33v perfectly, every cell from every 8p-pack is still identical in voltage to the cells it was parallel'd to.


I get my Accucell 6 in a few days, no good way to test anything until then, except by multimeter.

Sounds about right. He built a dinky 2.5A / 2500 mah 12v LIFEP04 battery. No wonder.

LFP, with it's extremely flat charge/discharge curve (except near the ends) means that 3.2v can mean anything from about 20-80% SOC. So you are correct in telling him to charge each one to 3.6v MAX, but his application at 10a means he is quickly killing them.

No mention was made if he knows about initial balancing, and or low-voltage disconnects - at either the pack or individual cell level.

The biggest problem is that unless you are an authorized A123 reseller, what you are selling is either counterfeit, grey-market rejects, or used old stock with pretty new wrappers.

I am reselling used old stock, I broke apart a 96-cell pack that was purchased on Ebay. It was purchased reconditioned at 80% (~15Ah instead of ~18Ah) original capacity, and I'm assuming as it's my first go, that means 5-10 cells of the 96 might actually be low/bad. I'll link my listing here, if it's unallowed I'll gladly remove it, but this is not to advertise my sale in any way, just for info's sake:

*link removed

I can always him a few more questions, but the buyer seems completely unaware of the chemistry. I, as a brand new seller, don't want to get duped. Best option I can think of is to give him a return label, if this continues. Here are his exact messages, just so you know what I do.

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Buyer:
Hello I tested 4 batteries charged 3.25 X 4 at a total of 13 volts at 10 amps and they didn't last even 2 minutes.
They are not even close to what you said what am I supposed to do with that
Bryce

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ME:
Very sorry, it does appear those would be well under the stated capacity. I am trying to warn all buyers that these are used and may have low capacity as I have no way of testing them, but I also guarantee the capacity at 1.8 AH fully charged.


It would seem though, that your test showed they put out 925mAh, and the batteries are actually only halfway charged at 3.25v. They must be charged to 3.6 to receive the full capacity. If you could do a full charge and get back to me, I'm happy to sort out any and all issues.


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ME
Actually, my math is a little off with the mAh rating there. Nevertheless, if you could charge the cells and drain them individually, it might just be that a single cell was draining the entire pack under load.

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Buyer
No I checked all cell's and they fell under 2 volts in 2 minutes
Yes your right your math is off

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This is where we sit now, he has taken another day and refused any more contact. Being the largest and only my second buyer, I might be overly concerned with getting a positive rating..

4s needs 14.4v applied till current drops to a low value and levels out.
your buyer is not getting them full.

I have many years of experience with A123 cells in my RC hobby. You need at least 3.5V per cell to fully charge them. When charging them as a pack, it must be ensured that the pack is balanced. The individual cell voltages must be monitored at all times.
The guy with the problems obviously has no clue at all.

Julian Holtz said:

I have many years of experience with A123 cells in my RC hobby. You need at least 3.5V per cell to fully charge them.

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Hi Julian

I have some 26650 A123 ANR26650M1A cells. The datasheet says:

Recommended pulse charge/discharge cutoff 3.8V to 1.6V

http://e-motion.lt/wp-content/uploads/2010/01/ANR26650M1A_Datasheet.pdf

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What does that mean?

This other A123 page says:

Recommended Standard Charge 2.5V to 3.6V CCCV, 60 min

http://www.houseofbatteries.com/documents/26650Cell.pdf

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What does that mean?

What is the recommended "full" voltage, and recommended "empty" voltage?
Recommended to charge to 4.2V?

Many thanks