[tewasch]

I've done dummer things....

Yesterday I was manually balancing my new 200 Ah TS pack of 34 cells and SOMEHOW forgot and left a 0.66 ohm load resistor connected to one cell all night (must have been the football game!). It drained that cell down to 1.6V (measured right after I disconnected).

I attached a 4.5V, 500mA wall-wart battery charger to the battery and in 10 minutes, it's now at 2.5 and slowly rising.

I'm curious what best practices are here to try and recover a battery from over discharge. The discharge rate was continuous (3-5 amps or so) if that matters. What should I expect?

Any suggestions? Anyone had any luck with recovering an over discharged battery? Thanks. Tom.

 

[Guest]

Just bring it back up to the voltage of the other batteries and don't do that again. Should be just fine. Don't walk away from a manual charger. Keep an eye on it and don't get involved with any other projects until your done charging that battery. Don't forget.

 

[Ziggythewiz]

I've done dummer things....

Me too!

Left the car 'running' for a few days once during a holiday...would've been really bad if the family hadn't come over for demo rides.

Felt dumber though when I did it the next week at work (for just 4 hours).

 

[icec0o1]

You might've decreased its capacity by 1-2%. It'll probably be the weakest cell in your pack so just keep an eye on it. As long as you don't force it to go into negative voltages, it won't cause you any problems or fires.

 

[GerhardRP]

Just bring it back up to the voltage of the other batteries and don't do that again. Should be just fine. Don't walk away from a manual charger. Keep an eye on it and don't get involved with any other projects until your done charging that battery. Don't forget.

Why don't you do a careful capacity measurement and compare it to a littermate from your pack. [I bet 2cents it is unchanged.]
Gerhard

 

[ssalbach]

I have do it with an 40Ah TS Yttrium..
I discarges them to 0V!!!!

You have to load it realy slowlnow!!!
If you load to fast..the will boil when it arrives arroung 3,9-4V!!!

You have to charge them now, like an new Batterie, very slow and to 4V


This was the Cell, I have discharched with around 70Amps!
http://litrade.de/pub/ts40ah_2wochen.jpg

Greetings from Germany
Sven
Litrade.de

 

[GizmoEV]

You have to charge them now, like an new Batterie, very slow and to 4V

Absolutely do not charge it to 4V! There is very little energy above 3.5V and it isn't worth the stress on the cell to charge it that high. There is a reason CALB lists 3.6V as the top voltage. TS should do the same.

You do, as Sven said, want to charge it very slowly at first. The Zivan charging algorithm is set to charge slowly if the cell voltage is below 2.80V and then to ramp up to full current.

Since you didn't run it to 0V the cell should be fine and not have lost much capacity.

 

[dtbaker]

The problem is going to be the state of charge for the other cells in the pack need to match your low cell..... you probably need to re-wire the entire pack in parallel, and re-balance the pack. If you top balance, I would NOT go above 3.8v for any reason.

 

[mora]

I have 31 90Ah TS cells which were at 0.1V when I got them. Some were less than 0.1V. I charged them in packs of 4 with 10A current until 3.0V was met. After that I charged them individually to 4.0V at 10A. None of them vented. Six of those drained themselves under 0.5V in less than a day. Others kept their voltages level. I Haven't done any real capacity measuring yet, but I suppose all the cells have lost lost of their capacity.