Re: charging NiMH batteries in a NiCd charger?

On Tue, 22 Nov 2005 23:22:19 -0800, Bob Monsen <rcsurname@xxxxxxxxxxx> wrote:

>On Tue, 22 Nov 2005 20:38:55 -0800, mrdarrett wrote:
>
>> So, is it ok to use the NiCd charger for the NiMHs? Will the NiCd
>> charger overcharge the NiMHs?
>
>Most NiCd chargers are designed for NiMH cells as well.

A large proprtion of standalone chargers are, but IMOE budget cordless phones
supplied with NiCd packs seem to be constant current chargers with no attempt at
charge termination. While NiCd cells will tolerate this reasonably, it is NOT
in the best interests of NiMH cells.

>They are quite
>similar, but the "end of charge" indication is slightly different with
>NiMH cells. Because of this, if your phone isn't built for NiMH cells,
>it may not detect end of charge, leading to overcharge, and overheating.
>Cells that are radically overcharged can get VERY HOT.
>
>I would not risk charging the NiMH cells in the unit; $12 is cheaper than
>a fire, or even buying a new phone. You might get away with it, but
>then again... If you go with a homebuilt pack, I'd advise you stick with
>NiCad cells.

Concur.
.

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