Probably a 1st year apprentice question, but can you substitute a NiCd battery of the same voltage/capacity in place of a NiMh without creating charging problems?
Different cell chemistries usually have quite different charging requirements (and usually different cell voltages too) - so unless the charger circuit is specifically designed for both, I'd say no.
Different cell chemistries usually have quite different charging requirements (and usually different cell voltages too) - so unless the charger circuit is specifically designed for both, I'd say no.