Nimh and nicad are completely different with regards to trickle
charging. Unless the individual battery manufacturer specifically states
otherwise, you should assume that continuous trickle charging will kill
nimh cells within a few months.

Also, some of them may not take a predictable amount of charge at 1/30C.

Nimh is the most complicated battery to charge.

How about lithium-ion or variants?

Cheerful regards,

Bob

Ariel Rocholl wrote:
> I have a single-item application that requires battery backup. I am
> planning, for sake of simplicity, to use 4 cell 650mhA NiMh and keep them in
> trickle charge permanently. Simple limiter resistor will put the trickle
> charge at 20mA max (<1/30C) which is far below the 1/10C most people comment
> as acceptable for trickle charge. The NiMh are high quality Kan batteries.
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist