0.0V Over-discharged cells - with some swelling

[JohnPickett]

Hi everyone. I read past posts about over-discharged cells, so I will start with the story. We are hooking up an EG4 12kpv at my 89-year-old neighbor's house. Al was a stud and still is, but he is old and proud. So, they took a lot of suggestions on equipment and such, but Al and Hippie decided to top balance and commission the cells. Well, it seems Hippie decided to hook up the battery to the inverter to see the lights come on and forgot to unplug them. No way weed was involved, I am sure. Well Hippie went to see Tesla...the band, not the car, and broke his leg. No way beer and weed were involved.

So after a month, I got a call from Al saying four cells read 0.0v, and 12 cell read about 1.0v. I have a cheap multimeter, but I did in fact measure 0.0v on four cells. All of the cells are swollen a bit. One cell is freaking swollen. I tried to take a picture below.

Okay, so I may not have helped. I took one of the 0.0v cells and hooked it up in parallel to three 1.1v cells, and let them figure things out. I have never seen a spark hooking up cells in parallel. I was thinking the voltages were so low. Anyway, things went to equalizing.

I have a bench power supply hooked up to the swollen cell. But I have a feeling that is a waste of time at least. Okay, I have a Kobalt multimeter. But four cells measured 0.0v. That pretty low.

What do you folks think I should do from here?

Thanks.

Cells - CATL 302AH Prismatic cells, about three months old.

 

[Koyaanisqatsi]

Sorry, I think you're going to have to eat this one. All those cells are trash now. New battery time.

 

[fatjay]

I have to say, 0v is damaged beyond repair. Even 1v is damaged beyond repair.

Was there a BMS on the pack? It looks like maybe. Did you have low voltage set on the bms so it would cut voltage?

 

[JohnPickett]

Guys...I just don't even know what to say. There was literally a JK BMS, with ring terminals on every wire, and Hippie hooked it up without the BMS. It is just such a waste. I just switched from overkill to JK...and I think I love them.

 

[Koyaanisqatsi]

I have never seen a spark hooking up cells in parallel. I was thinking the voltages were so low.

The power of high capacity at extremely low impedance means you can still dump tens or hundreds of amps over a 0.1v difference.

Guys...I just don't even know what to say. There was literally a JK BMS, with ring terminals on every wire, and Hippie hooked it up without the BMS. It is just such a waste. I just switched from overkill to JK...and I think I love them.

It's hard to argue against the cell voltages and the swelling. Maybe put a charger on each cell and see how it takes a charge.

 

[fatjay]

Never hook up a lifepo4 pack without bms, you're just asking for trouble. There are 3 lines of defense, the discharge voltage should cut off on the inverter, the then bms, then the individual cell bms cutoff.

You somehow bypassed them all.

 

[JohnPickett]

I came at off-grid solar from deer hunting from ebikes with lithium batteries that want to burn your house down. I just can't imagine someone hooking up cells without a BMS.