A123 Pouch Cell Recovery

[Sutho]

From your knowledge and experience, what voltage do you think is too low to recover A123 pouch cells?

A couple of the 7s3p modules I received have a cell group that was sitting at about 2.3V while the others in the same module are above 3.0V. I have charged these packs using an unbalanced PowerLab 6 and the low cells seem to have come up and are sitting at the same voltage as the others.

Note: I'm a novice with the PowerLab 6 and can't get the unit to do a balanced 7 cell charge. Keeps complaining about a wrong cell count even though I have it connected as per the manual. Any suggestions? :?

I assume the low cells will probably fall away again with a few cycles?

I read somewhere here that the cells are pretty much useless if they are below 2.0V.....but is 2.3V also damaging?

 

[texaspyro]

Katou sent me a couple dozen A123 M1 cells that were at a hard 0V. 2/3 of them recovered fully. A few other cells had a significant self discharge (dead again after a couple of weeks). The others were quite dead. One cell behaved badly when being charged. It went into a sustained thermal runaway and was quite hot hours after being removed from the charger.

I believe that as long as they were not subjected to reverse voltage you are quite likely to fully recover them. Do your charging with single cell chargers/lab supply, outside, away from all flammable material and small furry animals that yo wish to continue being small furry animals.

 

[rwaudio]

2.3v should be just fine for a one time event.

The PL6 can't do 7 cells (the 6 stands for 6S charge/discharge) the PL8 would do 7 cells (or 8s)

 

[Sutho]

Thanks guys. Sounds reasonably promising then.

The preset options on the PL6 will apparently do up to 8s balanced.....but looks like it will only do 1s - 5s, 6s or 8s? I tried incorporating the 1st cell group from another module to make 8s....but that didn't work either.

Anyone in the market for a virtually new PL6? :wink:

 

[999zip999]

Hope if not under 2.0v

 

[dnmun]

on the headway cylindricals, i had one at .25, 2 around .41, another few around .57-.67 and the rest were still around 2.7-3.2 after a year. they all came back, just a second on the voltphreak and they are 2.3V then 2.7 in no time, that is like the knee.

 

[999zip999]

Depends what demands you are going to ask.

 

[oatnet]

on the headway cylindricals, i had one at .25, 2 around .41, another few around .57-.67 and the rest were still around 2.7-3.2 after a year. they all came back, just a second on the voltphreak and they are 2.3V then 2.7 in no time, that is like the knee.

I've processed roughly 600 headway 38120s cells over the past few years, and it has been my experience that every cell that self-discharges below 2.2v never comes back. They charge back up to 3.65v, but most will quickly self-discharge to <2.2v in a few days, and the rest will last 5-10 cycles before doing the same. It is my theory that it is a problem with the cell drives them to self-discharge to a low voltage, not that reaching a low voltage damages the cell.

On a123 2.3ah/1.1ah cells, I have seen many at <1v that once charged, will hold >3.6v for weeks. I hope the pouches work the same way despite different construction and perhaps powder, but I have not experienced that yet.

A couple of the 7s3p modules I received have a cell group that was sitting at about 2.3V while the others in the same module are above 3.0V.

If the balance boards were connected, and the balance wires to that cell are good, I have concern for those 2.3v cells, because the boards should have kept them at the same voltage. I guess it is possible that the bad cell still has capacity, but a self-discharge rate that is higher than the balance board can compensate for. I hope you let us know how it sorts out!

-JD

 

[Sutho]

It is my theory that it is a problem with the cell drives them to self-discharge to a low voltage, not that reaching a low voltage damages the cell.

A couple of the 7s3p modules I received have a cell group that was sitting at about 2.3V while the others in the same module are above 3.0V.

If the balance boards were connected, and the balance wires to that cell are good, I have concern for those 2.3v cells, because the boards should have kept them at the same voltage. I guess it is possible that the bad cell still has capacity, but a self-discharge rate that is higher than the balance board can compensate for. I hope you let us know how it sorts out!

-JD

I agree with your theory. While the cells seem to charge up ok, I'm not expecting much from the modules that contain the recovered cells and haven't included them in my packs.

I will eventually replace the low cell groups with good ones from other packs....but would like to do a few controlled cycles with them first to see how they behave...

 

[mjcrow]

Hi Sutho,

The PL6 will do 1-6s balanced, and 1-8s unbalanced. The PL8 will do 1-8s balanced and 1-10s unbalanced. If you were a bit closer to me I'd happily lend you my PL8, maybe someone on the Eastern seaboard could help you out.

PS. Very cool project, good to see an Aussie pushing the boundaries 8)

Michael

 

[Sutho]

Hey Michael,

Thanks.....I probably should have done a little more research about what the 6 and 8 meant in the model number before buying the PowerLab. I ordered on recommendation from someone who didn't need to do more than 6s. I guess I'll just have to fork out for the PL8 and maybe sell the PL6.

Cheers,
Sutho