In article , "newshound" wrote:


NiCd seem pretty rare now presumably because of recycling and Cd toxicity.

I'd have said NiMH are now the standard, Li ion started in phones etc and
are moving to tools, but at a price.

For individual AA cells in cameras and GPS, I get much better performance
from NiMH than NiCd, but some of that is almost certainly thanks to using a
better charger which does each cell individually. I agree with Peter that
chargers have got better anyway and that tends to help NiMH.

I don't know whether the often described NiCd "memory effect" is true or
not, but over time I've seemed to end up with more "bad cells" in sets of
NiCd than NiMH.

The memory effect occurs when NiCd is charged after a fixed discharge
rate for a fixed time, as when charged by solar cells. When the time or
load is random, as with power tools, it's not a problem.

"Standard" NiMH have a relatively high self-discharge rate, greater than
NiCd. This means they lose their charge, at a rate of the order of
10%/month, when not used. There are now NiMH types (e.g. Sanyo Eneloop)
that address this problem, with some 80%-90% charge remaining after a
year on the shelf.

Li-ion doesn't have a similar high self-discharge rate, so is useful in
tools that are infrequently used.

--
John W
I you really want to mail me, replace the obvious with co.uk twice