> You can charge them fully in about 12-15 hours at about 50ma constant
> current charge. As far as I can see they can then be left on this 50ma
rate
> indefinitely without damage. In this case they will get  a little warm but
> as the cell generates oxygen (IIRC) it will chemically recombine within
the
> cell and no venting or damage will occur.

I've seen conflicting statements about this.  I've looked at a lot of
manufacturer info, so I don't remember exactly who said what, but at least
one manufacturer (Panasonic ?) explicitly says not to do this.  Others
explicitly say it's OK.  Unfortunately the Chinese company that made these
batteries provides virtually no useful information.

> So, based on this I am thinking of building charger that charges at 2/3C
or
> 1C until it sees the drop, then dropping down to 30ma or so to peak the
> charge and hold the battery at full charge.

I would have an alternate terminating condition in case the blip doesn't
occur.  I've been looking at recommendations from various manufacturers, and
some of them come right out and say that the blip might not happen
sometimes, even at the high charge rates.  My conclusion is that it's a good
indicator when it's there, but you can't count on it.  I've seen the blip
once at .1C, and several times not at .2C.  Apparently the blip is also less
prounounced as the cell ages.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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