I have ordered some batteries off of ebay and also a maha c777 charger too, I have some NIMH c cells w tabs 4500 ah, enough to build 2 4.8v packs. The lights I have are from Wheat Miner's lamps, they originaly come with a 4v lead acid battery, but it is kinda bulky and wont fit well on the bike, so I opted for the rechargeables to save weight and can stack them in a bottle. The lights have double filament xenon bulbs, not sure of the wattage, I have used them underground, and with the lead acid battery, they last forever, >8hours and throw a considerable amount of light. I will be running 2 of them on my bike and maybe one on my head. Has anyone ever modified these lights for biking?