I'm using RadioShack Rechargeable, 700 mAh, NiMH in my TL-LD500s. They last me over a month. First weekend of every month I rotate all my NiMH onto the charger, whether they've been used or not.

However, my halogen lights take 4 AAs. Those are RayOvac NiMH, 1800 mAh, and those I have to recharge after every second ride.