Lithium Polymer, Resurrecting cells?

[2camjohn]

Due to a little mishap with my protection board, I managed to very slowly discharge a 2 cell lithium battery down to pretty much dead (0.05V per cell).


After half an hour of trickle charging it got up to 0.25V per cell.

My question is, can I resurrect it?
Or am I just wasting my time?


Thanks
John

 

[dknguyen]

Tread carefully. I would ask on an RC plane forum where they would have much more experience.

 

[HarveyH42]

I thought the lithium batteries catch on fire if you over discharge them? Maybe it was over charging them...

 

[jpanhalt]

Most of the fires I have heard about were upon charging overly discharged cells or over/improper charging any pack. Improper discharge can also cause problems. In the past two years, one member of our group has had one set of cells get really hot -- we destroyed it in a dirt bunker -- and one set bulge and get real spongy. It was similarly destroyed. Both incidents were upon charging. As for the risk of a problem, he probably has a total of about 3 packs to use during a flying season and is the only member of our club who uses them regularly.

He was using a charger "designed" for LiPo's at the time, but swithced to a different battery charger this Summer and has not had any problems since. We are still very cautious, though. I would not mess with LiPo cells. John

Edit: By mess with, I mean abuse. I started using LiPo's in a powered glider this Fall. They are great batteries. You just need to treat them right.

 

[audioguru]

Recently I saw a huge RC model airplane start smoking in flight. The pilot quickly landed it then plucked out its Li-Po battery that was smoking badly but without a flame. The battery was brand new and was very expensive. It smoked when covered in a mound of sand for about half an hour.

I have an RC powered glider. It uses a Ni-MH battery that is heavy so the glider glides like a brick. Lots of fun!

 

[Ambient]

I would toss the cell, it is very risky trying to mess around with a bad LiPo. The batteries can overheat if discharged or charged too fast. Too much discharge current will kill a pack, which I learned the hard way.

You are better off disposing of the cell. The manufacturer websites have directions for doing so safely. Or you can have some fun OUTDOORS with it hehe.

 

[2camjohn]

Thanks for the info Guys, Ill play it safe and get new cells.


I too thought there would be problems with swelling etc when discharging the LiPo that low.

All I can think of, is that the rate of discharge was too low for anything to happen.

 

[audioguru]

Lithium is a very active metal. The compound that is used in a battery becomes unstable if it is discharged to a low voltage. The rate of discharge has nothing to do with its instability. It could spontaneously ignite.

You have seen magnesium flares burning with a very hot white flame? Lithium burns the same. Don't put water on the fire. It makes it hotter.