Simple Wet* Cell - Battery
Note how I used a longer piece of copper for the very bottom of the base cell, and a longer piece of galvanized steel for the very top plate of the top cell. This allows a place for my alligator clips.
I have limited knowledge on the chemistry of what's happening here, but I understand that oxidation (exchanging of electrons) is taking place between the two metals. The zinc on the galvanized steel is losing two electrons to the copper plate through the load. (Why not thorough the electrolyte? I wish I knew ) The copper which received the electrons, discharges through the electrolytic solution which finally renders the imbalance back to the now positively charged zinc atoms on the plated steel.