On Monday, Mar 22, 2004, at 08:51 US/Pacific, David VanHorn wrote:

>> Constant current at 0.1C for 12-14 hours.  Ie a reasonably stable
>> voltage supply and a resistor...
>
> Check the cell spec.  0.1C constant charge takes a special NIMH cell.
> Sanyo's C series are rated for this.
> Some NIMH cells are rated for ZERO constant (unterminated) charge
> current, and they aren't kidding.
>
Thus the 12-14 hour comment.  Which assumes dead or nearly dead cells
to start with.  But it is the "minimum" circuit, and (perhaps sadly) is
what you'll find in an awful lot of the consumer chargers on the market.
A lot of the remaining ("Fancy") chargers do something special for a
fast charge, and then "drop down" to .1c or .05c for "float", whether
it's a good idea or not.  Note that battery manufacturers aren't really
motivated to provide algorithms that maximize cell lifetime :-(

Given their annoyingly fast self-discharge, it's very frustrating to
not be able to float-charge NiMH without adverse effects...

BillW

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