On Thu, 25 Feb 2010 17:58:45 +0000, Fred
wrote:

I'm likely to buy nimh. Why are these preferred over nicd? Is it just
that cadmium is not friendly? Is there any advantage to ever using
nicd?


NiMH batteries tend to have higher capacity. NiMH batteries seem to
last longer. NiCad batteries duffer from an earlier reduction in
capacity than NiMH.


Would one charger charge both if I ever needed or are some
chargers nicd or nimh only?


Some "intelligent" chargers will charge both types.


Finally, I see that AA batteries are rated at 2700mAh and C and D
cells are rated 2600mAh. I would have expected a larger battery to
have had a higher capacity; why not?


You can buy higher capacity C and D cells in some brands. In other
brands, they just put an AA cell inside a C or D size casing.