[Markulous]

What sort of batteries, Ray?

Generally:
NiCd (the older rechargeables, used less and less these days) - always use until flat and then recharge
NiMH (more usual AA AAA rechargeable batteries) - don't really need discharging but an occasional full discharge is thought to 'condition' the batteries
Li-ion (shaped batteries, so ideal for small or irregular shaped items plus excellent performance) - don't need discharging (and are prevented from a full discharge which 'kills' the batteries). One downside to Li-ion is that they have a limited life from date of manufacture (even if you never use them), another is that if they're damaged they may release the whole charge in a very short time (explosively/inflammably)