In my Hydrogen Fuel Cell set up, I used a set of 8 AA batteries as my energy source which had a total of 12 volts. The the current flows through the wire and Oxygen and Hydrogen are collected at the electrodes (pieces of graphite). When I flip the switch, the connection to the battery is cut and instead the two graphite leads are connected to a small LED light. The Hydrogen and Oxygen recombine to form water and electric energy. The electricity flows from the water and lights up the LED light. Awesome!
