> I will convert to NiMH; just a NiMH charger circuit, no balancing
> needed. The small amount of weight savings doesn't justify Li-anything.

After my experiences with NimH over the last few years I'd be very
wary of using them in lieu of eg LiIon.
If each cell can obtain its charging energy from an independent
(effectively "floating") source (as opposed to a series string with
common current) then each module becomes an independent charger and
any sort of cell becomes essentially no harder or easier than making
single cell chargers.

If you have a series string with charge current flowing down the
string then NimH is going to have to deal with unwanted current just
as LiIon is. My 'short circuit the feed when unwanted' system would
work as well (or badly) there.

NimH used in a series tring of substantial length do need balancing -
especially modern ones which, unlike those of lower capacity, cannot
tolerate ANY long term trickle charge. With cells that support trickle
charge  a string may be balanced "reasonably well" by charging all
cells to near full capacity then trickle charging the string for an
extended period. Modern NimH with high capacity per volumes (eg say >-
2000 mAh in AA) do not tolerate trickel charging.


        R
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