HP-34C external battery charging

[Dieter]

(12-06-2017 09:16 AM)Frido Bohn Wrote:  I've changed the original, now useless NiCd batteries with AA-type rechargeables with a low self-discharge rate (e.g. eneloop from Panasonic).
They really hold the power for a long period if you use the calculator only sporadically.

I think that's definitely the way to go. Current Eneloops have about four times the capacity of the original NiCd pack, and they hold their charge extremely well when not in use. Connecting the two batteries can be done with a thin piece of metal, I even use folded aluminum foil in my 34C.

Charging should be done in an external "smart" processor controlled charger, as recommended several times in this forum, e.g. the BC700 series and its siblings.

Dieter