How to bring an overdischarged lipo back

[trailduster79]

The title says it all. My charger won't let me charge my lipo becuase the voltage it too low.

I apparently left it hooked to my ESC over a couple nights and it has drained one cell to 1.95 and the other to 2.0.

What can I do to bring the voltage back up? or is it dead for ever?

[squatch71]

From what I read...its dead...sorry...but someone might of tried just charging at say 1/2 amp for a long time...did you try that??

[JSN]

two choices... recycle it(shit can) OR charge it SLOWLY on a NiMh setting... monitor the battery voltage and as SOON as you hit 6v(assuming 2s) stop and balance charge it on a lipo setting.

[trailduster79]

gonna give it a shot.

[ScalerLover]

I know someone that brings theirs back up on an Nimh charger, just keep an eye on it and im sure you will be good

[trailduster79]

only took 30 seconds at .5 amps to get the voltage up to 6V. Gonna balance charge it now.

Thanks!

[XPLORx4]

First, read this:
http://rclovers.com/Discharge.htm

Then, read some of these links:

http://www.rctech.net/forum/radio-el...rged-lipo.html
http://www.rcgroups.com/forums/showthread.php?t=759044

Use extreme caution when trying to revive your LiPo.

[lostwages]

i did the same with one of my lipos, i hit it with 5 amps for about 15 seconds, it came up to voltage quick and i charged it on the lipo setting like normal, this battery is over 2 years old now and still works like new.

[trailduster79]

this is a 1000mah pack for my mini-t


So far it is balance charging great.

Thanks for the help!

[lostwages]

oh, well yeah, dont hit that pack at 5 amps, mine was a 4500 2s pack lol, glad you got it working again.

[trailduster79]

it took 982mah so I am happy with that.

[ittybitty]

another option...if you have say a 11.1v you can charge it on the 7.4v setting without balancing and itll bring it up enough for the 11.1v balancer to recognize it and continue to charge it...ive done that once.

[squatch71]

K, since a couple brought it up and didn't explain...why charge the Lipo on NiMh till it hits 6V (2S) what is the charging difference between the Lipo charge and NiMh charge?? different pulse??

[rockhugger]

I just had a dream that one house in every city spontaneously caught fire because we all tried to revive our lipos. this stuff scares the ba geezuz outa me. Once copper forms inside the cells it can short circuit, seems to me like the battery becomes unstable. Doesn't seem worth it to risk a fire. Maybe I'm just a scaredy cat.

[MadForce]

^That is why you buy a liposack for 30$ or less. Trust me I have allready thanked this bag in the past. BTW When my charger does not recognize a lipo at its; nominal cell count, I usually just let it cool down and "relax" a bit first. Most of the times the 1st cell balances it self up to 2.8v at which point the charger recognizes the "dead" cell.

[Alex.G]

i used slow nimh mode to bring my old lipo alive, still working

[Boogie]

Originally Posted by squatch71

K, since a couple brought it up and didn't explain...why charge the Lipo on NiMh till it hits 6V (2S) what is the charging difference between the Lipo charge and NiMh charge?? different pulse??

Most new chargers, when charging in LiPo mode, do a quick test on the battery to see if the minimum voltage is there. If it isn't, it doesn't initialize the charge and proceeds to make a lot of beeping noises until you unhook it...at least mine does, lol. NiMh mode though, doesn't have that minimum voltage check, you just punch in the charge rate and hit start. Sometimes, as long as the voltage isn't too low, you can revive the lipo enough on NiMh mode to give it the minimum voltage to pass the LiPo mode initialization.

Someone mentioned charging in a lipo sack...I've seen enough videos to know what kind of hellacious fire they would start if something went wrong, I use an old ammo can.

[Big Mike]

another option...if you have say a 11.1v you can charge it on the 7.4v setting without balancing and itll bring it up enough for the 11.1v balancer to recognize it and continue to charge it...ive done that once.

I've done a slightly different version of this method a few times myself and it's worked for me.
I charge at a lower cell setting w/o balancing long enough to bring the pack back over 6 volts, then reset my charger to the proper setting for the pack and start over.
Just place it someplace safe while charging, and CONSTANTLY monitor it, just in case.

The first time I did it was with a brand-spankin-new 3S pack. I told myself I was gonna blow the damn thing up before I just wrote it off and chucked it in the trash. I charged it for a while w/ the charger set for 2S and the balancer unplugged, and brought it back over 6 volts. Luckily it worked, and I'm still using this pack today.

only took 30 seconds at .5 amps to get the voltage up to 6V. Gonna balance charge it now.

That is consistant with my experience, it has never taken more than a minute to bring the pack back up over 6 volts, at which point normal LiPo charging/balancing procedures may resume.

BTW, unplug your LiPo from a Tekin FX-R when not running, even if the switch is OFF it seems to dump the pack. This was how I ended up w/ over-discharged LiPo's in the first place...

[EeePee]

I've used a 2S lipo to zap a 3S lipo back to life.

Double the risk!

[Big Mike]

Someone mentioned charging in a lipo sack...I've seen enough videos to know what kind of hellacious fire they would start if something went wrong, I use an old ammo can.

I've seen lots of videos too.

My personal experience is different. I've NEVER ONCE had any of my LiPo packs get anywhere near warm while charging. At all. They never seem to get any warmer than the ambient air temperature around them. They always take the mah and voltage levels specified on the labels, and I always get great run times out of all of them. I just don't experience the heat everyone else seems to.

At first I was almost scared to hook the damn things up to the charger (Hyperion EOS 0606i) I'd heard and seen so many "horror stories" about LiPo accidents. I set the charger up in my garage floor and layed the packs in an old cast-iron skillet walled off w/ bricks while they charged. I just laugh now thinking of the precautions I was taking then, due to all the stuff I'd read.

Now about a year later I leave 'em in my rigs while charging, leave them unattended, etc. I've never had one even begin to get warm, much less hot enough to damage anything...