[chbot] LI Ion battery 0v

[Chris Hellyar]

For what it's worth...

I had one cell in a 1Ah 2 cell LiPO pack go to zero volts and tried to 
trickle it earlier in the year.

I put it outside in a cunningly created brick 'firebox' made from some 
earthquake provided chimney material.  I tried trickle charging at 5ma 
for about 12 hours, and it only got up to around 1V and dropped back to 
something like .2 or .3 when I removed the supply.

In 'nothing to loose' mode I opted for the 'pulse' option using a 
10,000uF cap charged up to 12V a few times (from 'outside' the bricks 
and at the end of 5m of cable!!!).  that pulled it up to 2 and a bit 
volts so I then connected it to my LiPO charger in and left it running 
at (I think) 200ma.

At some point over the next hour or so it let the magic smoke out in 
spectacular LiPO fashion, getting hot enough to melt the insulation on 
the clip leads back about 100mm outside the small gap in my 'firebox'.

Some of the R/C forums are full of all sorts of witchcraft and tricks to 
try and recover larger more expensive high 'C' packs, and it's certainly 
worth a shot, but be real careful with the Lixx cells, that's for sure..

Cheers, Me.



On 15/11/11 13:11, Charles Manning wrote:
> On Sunday 13 November 2011 10:21:36 Marshland Engineering wrote:
>> Hi I purchased a large 3 cell Li-Ion battery pack off eBay. After one use,
>> one cell is at 0v. The other 2 are 3.7. Can the cell be kicked back into
>> life ? My guess it is internally shorted.
>
> Were they in series? If so then the 0V cell has likely been reverse polarised
> with can be seriously bad for the cell.
>
> A recharger likely won't want to try charge it until it gets to a reasonable
> voltage. Try trickle charging at a few mA for a while and see if that gets it
> back into charging range.
>
> NB Given the bad things that can happen with Lithium in the picture, only fool
> around with these things outside and away from anything that you care about.
>
> -- Charles
>
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