Stuffed lipo?

[thermite]

I did something a little stupid yesterday and think I managed to balls up one of my new 1.3A Nano's  Just put the props on my 250 and thought I'd test the board by doing a spin up and a few hops in the lounge.  I'd never charged the lipo's and thought they'd have enough juice for what I wanted to do for a couple of minutes.  I found that the motors wouldn't spin up after a couple of minutes pissing about and didn't have my lipo alarm attached.  The voltage had dropped to less that 8v (3s)  It's now showing over 9v but the cells appear to be out of balance.  Could I recover this pack or should I dispose of it? 
Schoolboy lesson learned there.

[dogzilla]

If the cells are resting at or above 3.0v per cell then most likely it can be salvaged.

Put them on a very slow charge like 0.1A to get the cell's back to more than 3.6v and then you can continue charging at a higher rate.

There is a good chance you've knocked a bit of life out of them but yeah as long as the cells aren't below 3v the cell chemistry is still OK.

Once you go below 3v they are pretty much toast.

[thermite]

Thanks, I'll see what I can do.

[thermite]

Actually, one of the cells is sitting at 2.88v  The others are over 3v

[BlueFlyer]

you shouldn't really take risks with LiPos.

My personal rule has always been... If I even THINK it might be damaged, get rid of it.

It really isn't worth the risk mate, just for a tenner's worth of battery... take a look at this thread: http://www.fpvhub.com/index.php/topic,21318.msg170289.html#msg170289

there are many things that can cause a LiPo to fail like this, overcharging, overdraining, physical damage, factory faults...

[thermite]

Thanks for the advice.  I've managed to get the cells above 3.6v without anything dodgy happening.  I'm going to carefully experiment with it.  It will however be kept in safe isolation.  First sign of it misbehaving and I'll discharge and dispose.

[stevec]

I over discharged a pack in the past.

Put it on a nimh setting and charge it at 0.2a or so until you see it over 3v per cell,  then a normal 1c balance charge should bring it back.

I plug my cell monitor into the balance port for this and I also do it on the patio away from anything flammable.

Yes messing with lipos I'd dangerous but if there is no physical damage then it should be ok.

Cheets
Steve

[rob.thomson]

I have used that technique many times.

Works well.

Just use normal good practice.  Do it all in a fireproof bunker!

[thermite]

Thanks guys.