Originally Posted by meanwhile

Shadow - try to find out if any of those lights are regulated, so that brightness is constant rather than varying with remaining battery charge.

Fenix have just launched an 18650 light, btw. It will cost more, but their quality is usually excellent.

Oh - and never leave an 18650 on charge and go out of the house or where you can't supervise it. Not if you're using a made in China super-cheap charger and cells. There's a slight risk of fire. High quality protected cells and the Swedish Pila charger cost more but are safer.