I've been playing around with building an electric bicycle for awhile now. What I'm describing here is about version 3.6 of the project which was one of the original projects that gave rise to Transmutable Explorations. Currently, the bike is powered by 4 6-Volt Sealed Lead Acid batteries housed in a custom plastic box complete with key switch and plug serving double duty as charge port and distributing power to the bike itself. There is a DC Controller under the battery pack which takes the input from the throttle and kill switch attached to the hand brake and controls the flow of electricity to the hub mounted DC motor. The current version is great for daytime electric-assisted bike rides (and most people will need it considering the weight of those SLA batteries!) but it's not ready to blow wind through your hair on an extensive outing. We've learned a lot from this project, and the current battery pack has become a reusable module that we transfer between several other electric vehicle prototypes. We will document future enhancements as they occur.