lipo battery problem

[CRAWLERJOE]

I have a 3s 5000 mah 20c battery that may have been accidentally left plugged into my charger over night and is now reading 2.99 volts on cell 1, 1.89 on cell 2 and 2.38 on cell 3! My charger gives me an error code of voltage to high/low and won't charge the battery!

So should I call this a lesson learned and trash the battery or is there some way to recover the battery?

[alexchen86]

Ouch...I would try bump charging for about 5-8 min w/o the balance tap plugged in and your charger in NiMH mode to boost your 2nd and 3rd cells above 3.0V. Make sure you either put the lipo in a lipo sack or do what I do and put it in an army surplus ammo can with a closed lid in case it puffs.

Good luck!!

[mindless]

Ive done this before with some luck charge the batt on nimh at like .1 and keep a close eye on it do not try to fully charge. Should bring the voltage up to where you can put it on the lipo setting and not get the low voltage error. I usually will charge it for a short while try lipo if it doesnt work go back and repeat.

[alexchen86]

The worst I've had was a crappy 1550mah 3s MaxAmps pack that I submarined using an XL-5 ESC with no LVC and the pack actually swelled up 20% larger than normal. I let it cool off a couple of hours....readings on the cells were around 2.8V first cell, .92V second cell, and 2.6V third cell....after bump charging it was fine. Of course after bump charge you balance it using the Lipo Balance feature on your charger. Then I would recommend Lipo Discharge if you have that feature to reduce it back to around 3.2V/cell. Then balance charge it back up to 100%. Luckily for me my MaxAmp pack actually returned to life....and this was 3 years ago. Still using it today on it's fourth year with no issues.

This entire process is sort of dangerous so make sure you either do it outside or somewhere where you can quickly dump the lipo into a big bucket of salt water.

Lipo storage and proper care is critical for any electric r/c. Sometimes with low quality packs or even high quality packs you never know what may happen....one of our crawler guys had a little 3s 450mah pack explode in his lipo sack while he was driving down the freeway. Thank God it was in a lipo pouch and didn't burn through his seats or damage his truck....

Lipo's are dangerous but if treated correctly you shouldn't have issues. NiMH packs are just as dangerous if you run them too hard....they may not explode or flame up but they will destroy your r/c if not taken care of properly while running!

[CRAWLERJOE]

Thanks for the input! I will give this a shot when I have some time!

[Charlie-III]

Do a "1C" charge (5amps) on a NiCD or NiMH type for ~1 minute.

Then go to a "1C" (5 amps) LiPO charge for ~30 minutes. Finish off with a LiPO balance charge.

The NiCD/NiMH charge is just to get the pack voltage up to minimum LiPO pack voltage. It is NOT a proper way to do a LiPO full charge!

As mentioned, make sure the pack is away from stuff that burns.

BTW, how did leaving it connected to a charger overnight drain the pack??
I don't ever remember having that issue with any of my chargers & LiPO's before.

[CRAWLERJOE]

I have mo idea! I was always told to never leave them plugged in as it would damage the battery! I am not sure if it is true or not, but it is the only reasonable explanation I can come up with! My lvc is set at 3.2 volts on all my trucks, mg lipos have never been wet, they have always been balance charged! So aside from leaving it plugged into the charger I really have no idea!