4a) Apply DC voltage at 2.6V for 6min to steel (positive) in a caustic potash bath heated to 90C with another piece of steel as the electrode (negative) also in the bath.
4b) Apply WD40 to increase the lifespan of the steel (optional)
5a) Repeat steps 4a-b for copper.
6a) Wrap copper in tissue.
6b) Wrap steel in carbon felt (welding blanket) (or any carbon flame retardant or graphite/diamond coat) although carbon felt can go on either the copper or steel oxide.
I am seriously considering keeping the raw materials for this type of battery on hand if SHTF. Gravity Battery
The gravity battery utilizes two common chemicals which create an electrical differential to generate a current. The "Gravity" aspect refers to how the specific gravity of each chemical causes them to separate themselves naturally into a positive and negative side, all contained in a glass or plastic container.
The Greenhouse of the Future ebook by Francis Gendron