JeffinTD

If I recall correctly, nicad generally has a longer life in terms of charge/discharge cycles, where nimh generally has higher energy density (more milliamp hour capacity for the weight).

Anyway, newer ones seem much less effected by memory- damage from repeated shallow discharge/recharge cycles.

I would just charge it when you see fit, though it wouldn't hurt to run a charge/discharge cycle a couple times a year on a smart charger. Mainly so the smart charger will give you the pack's capacity. If the milliamp hour capacity the battery produced is way under what the pack is rated for, that would be a good indicator the pack's condition/performance is going down hill.