Alum rainwater cell – good 2.7V initial charge
Recently, alum has been used to replace the acids of car batteries. I wondered if alum would work as an electrolyte on a lot smaller scale and by using galvanized steel and copper or other positive electrode. With burnt copper, the output in tests today has been just above 1V with about 12mA, but with graphite some very good charging results have been obtained ! A Joule Thief is shown running, to prove the cell has decent enough amperage, for something using what would normally produce around 0.8V and a milliamp or so. The cell is, of course, rechargeable and is improving with use. It needs a larger surface area of graphite, that is already a given as these replacement pencil pieces are of tiny diameter. I find it interesting that alum was used as a protector of metals within Bedini Earth Light cells and others….so maybe this cell will last a while. A charcoal colour has appeared on the galvanized steel and it’s unknown whether that is correct for a long term runner, or is a semiconductor layer or something else.