[chbot] LI Ion battery 0v

[Hanno Sander]

Many cells now come with a protection circuit that tries to keep you
and your battery safe.  It effectively disconnects the battery under
the following:
- battery voltage too low
- external voltage too high
- current too high
- possibly temperature too low/high

If your cell has such a circuit and it's faulty, you may be able to
replace just the circuit.  Alternatively, if the cell's voltage is too
low, you may be able to directly charge it enough to bring its voltage
in the required range.
But no matter what, be careful!
Hanno

On Tue, Nov 15, 2011 at 2:01 PM, william <fleetwil at gmail.com> wrote:
> there is a video on the eevblog that talks about charging LiIon cells, i
> believe constant current until the cell reaches around 2.7 then constant
> voltage (4.2V IIRC)
> if the cell is a dead short then you may have to use a high current (gel
> cell, Pb H2SO4, rectified heater supply from a MOT ) supply/battery and try
> blowing the short out (PULSED)
>
> -----Original Message-----
> From: Charles Manning
> Sent: Tuesday, November 15, 2011 1:11 PM
> To: Christchurch Robotics
> Subject: Re: [chbot] LI Ion battery 0v
>
> 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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