charging NiMH vs NiCad

Google is your friend.

Trickle charging is not good for nicads, probably not real good for NiMh cells either, if nothing else the heating effect won't help.

Due to the larger capacity of the NiMh cells, expect to wait 30 hours, or longer, for a full charge.

Bye. Jasen

Thanks for the link. I found an answer that makes sense, unlike some of the help that was offered in here....

"Asking about the difference between NiCd & NiMH battery chargers -

The Cadex site

The charge termination criterion is different. Most NiCd chargers stop (or transition to trickle charge) on a characteristic voltage drop. The NiMH voltage drop is more subtle. Most NiMH chargers transition based on temperature.

The NiMH cell requires a smaller trickle charge. "A trickle charge that is acceptable for the NiCd will overheat the NiMH and cause irreversible damage."

The answer is only "possibly".

How do you tell if a nicad is full...well the voltage drops ever so slightly. Many chargers look for this drop and switch off. If that fails they have a safety timer as a backup. NiMH cells have a much smaller voltage drop and the a NiCad charger can fail to detect it. In a fast charger this can result in the cells being over charged and damaged (a fire even). In a trickle charger the safety timer may or may be triggered before the cells are charged.

So in your case the most likely outcomes are either:

a) It all works ok b) The cells are overcharged, get a bit warm/hot and their life may be shortened. c) The cells may never be fully charged because the safety timer kicks in.

If you house burns down - remember that I recommend you buy a charger designed for NiMH cells. They aren't very expensive and sometimes come with free cells.