>I have seen from previous posts that a LION battery can be C/10
> charged to 4 volts if you can accept the loss of some stored energy.
> The charger could simply be a voltage limited current source.  If you
> have a string of LIONs can you charge them to 4*N volts where N is the
> number of batteries ?

Notionally yes, subject to all the things-going-wrong caveats. BUT I think 
you'll be well down on 10% if you stop at 4V.

Without checking, 4.3V is full-full. 4.2V somewhat down. 4.1V significantly 
down - maybe 10% to 20%. 4.0V would be lower again.

There are two stages of course - Some selected I value I to maximum design V 
then tapering I to some endpoint. By stopping the I taper at about C/5 you 
take about 10% off capacityy but about double cycle life. By setting Vmax to 
4.1V you take about 10% off capacity but double cycle life. By doing both 
you MAY take 20% off capacity but quadruple cycle life. But Murphy and the 
law of diminishing returns suggest you may get less than that. I intend to 
do some trials but haven't done so yet. (The road to hell is paved with 
...).

In your 4V max scheme you still need to decide a taper cutoff current.

By charging to about 4V3 and then stopping (with no current taper) you get 
about 2/3 capacity BUT it takes about 1/3 of the usual total time and the 
battery is left at its optimuj storage state for long life.



  Russell

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