Lipo batteries dead -recover or discard?

[daniel..]

Ok, i screwed up and left the batteries connected to the wattmeter and controller for two days. The battery (lipo 10s) is fully discharged (shows 9.7 volts of 37v nominal). My idea is to attempt to charge it carefully (outdoors inside a lipo bag). Is it too dangerous?

Thanks,

Daniel

 

[Ykick]

Ok, i screwed up and left the batteries connected to the wattmeter and controller for two days. The battery (lipo 10s) is fully discharged (shows 9.7 volts of 37v nominal). My idea is to attempt to charge it carefully (outdoors inside a lipo bag). Is it too dangerous?

Thanks,

Daniel

No, take precautions, closely monitor cells using .5-1A charge rate. Can you rig up some concrete blocks or fireproof surface instead of the bag? Would be a shame to miss a good pyro show and ruin a bag for outdoor charging, ya know?

Low current deep discharges while not sitting in that state for long period of time will likely have a positive outcome. Of course, there may be problems down the road so remain wary...

 

[dogman dan]

Might be saveable due to the slow rate of the deep discharge. But I would mark all those packs somehow, and consider them to be charged in a safer place from now on. Outside, inside your oven at least if outside is impossible, or inside a really sturdy lipo bunker.

I wouldn't trust em for daily use anymore. Wouldn't sleep untill they were stored in a sturdy bunker, etc. Fodder for a fun overcharge experiment and video, or completely discharge and dispose of them.

 

[daniel..]

Thank you. I charged them yesterday to storage value at 0.5 amps. So far so good. No puffy cells, nothing strange and Thye have kept the charge overnight. Now topping them up to 4.1v, at the same speed. I always store lipos in a lipo bag, in use or not, and charge them inside the bag with the bag inside a cooking pot, lid closed. I plan to do the same and balance charge them slowly (at 1a or so) from now on. Does that sound enough? It is only two 5s packs, if this is really risky I can discard them.

 

[Ykick]

I don't think it's too risky. No voltage leakers or puffing, just keep an eye on 'em and handle with care. Sounds like you already do.

This event is exactly why I never, ever, leave active electronics connected to RC Lipo bricks. All due respect to well meaning BMS, metering and LVC devices, it's just not a risk worth taking IMO.

 

[daniel..]

Thanks again!

 

[daniel..]

Update: did what Ykick recommended, and so far they are working and keeping balance as if nothing had happened.

Thanks,

Daniel

 

[Ypedal]

what brand are these ?

 

[dak664]

As I understand it the danger is now internal shorts from chunks of replated copper being dislodged. I'd sleep better if after a full charge it survived a couple drops to the floor. Of course you have to balance that with the possible damage it could cause. YMMV, but I crash my (LIFePO4) packs enough for a drop to the pavement to be rather routine.

 

[dogman dan]

I agree, the pack works again is very different from the pack is safe to use like normal. They wouldn't enter my house or garage.

In my case, I could keep em outside, and run a lawnmower with em safe enough.