Originally Posted by TokyoSeven
I was not aware battery composition had anything to do with charging time. However I am not an expert on the topic.
It has to do with how efficient the cells are at retaining energy. For example, Ni-Mah are more effcient cells than Ni-Cad, and retain about 80-85% of the energy put into them (thus charge time for NiMah is charge rate times 1.2), whereis (IIRC) NiCads are around 70-75% effcient (charge rate of 1.25 times mA output).
I could be wrong, but I think that's about right.