Originally Posted by AllenG
It's best to fully discharge and then recharge a NiMh battery, it helps to prevent "memory effect". That said, don't store a battery partially charged, it's better to fully charge a battery that is not going to see regular use.
NO! You do NOT want to make a habit of fully discharging a NiMH battery! A NiMH battery will lose its ability to hold a full charge more rapidly the more it is deeply cycled (discharged to nearly empty, then recharged). Older
NiCd batteries WERE prone to the "memory effect", but this is much less important for
NiMH batteries... for optimal lifetime a NiMH battery should only be deeply discharged every few months (see the site I've linked below).
An excellent online authority on rechargeable batteries is Battery University, here's a page on nickel-based batteries with useful facts about NiMH and NiCd batteries:
http://batteryuniversity.com/partone-4.htm
I refer often to Battery University since I often have to restore expensive and unusual battery packs for laboratory equipment. The site explains charging algorithms for different types of battery chemistries in great detail.