Join Date: Sep 2005
Bikes: Windsor Fens, Giant Seek 0 (2014, Alfine 8 + discs)
Should be trivial. I think they're 6 volts. Find a 6 volt battery and hook it up. If it's one of those where there's one wire coming out of the battery then hook that wire to one side of the battery, the other side of the battery to the frame of the lamp/bike. A 4 cell battery holder will work for 6 volts. Or you could use two LiIon batteries, they're 3.6 volts each. The light should handle the overvoltage and you'll get more light.
Work: the 8 hours that separates bike rides.