- Get 1 rod of solid magnesium about 1″ in diameter and 1 to 1.5″ long. (Check Amazon, Ebay, or your favorite site for odd stuff. I think an electric hot water heater uses long magnesium rods.)
- Get a copper plumbing cap wider than the magnesium core, about 2″ in diameter, about 1.5″ deep.
- Put 1 steel screw in the center of the magnesium rod.
- Glue a cardboard circle to bottom of magnesium core and place core into a 2″ wide copper pipe cap.
- Now powder 1 part each of these in a coffee grinder: alum (usually a hydrated double sulfate salt of aluminum), Epsom salt (magnesium sulfate), potassium chloride (salt substitute), borax (sodium borate, sodium tetraborate, or disodium tetraborate).
- Mix the powders well. Put copper cap and magnesium core (with cardboard) on a hot plate on lowest heat.
- Slowly add powder inside the copper cap around the magnesium core.
- Let the powder all melt, do not let it bubble, and pop any bubbles with a wire.
- When it’s all melted let it cool in 1″ of room temperature water in a metal pan.
- To test, apply electrodes to screw and to copper cap to measure about 1.4vdc of voltage which should last at least 2 years.
Put more batteries in series to increase the voltage. 3 cells makes 4.2 volts, which can be boosted to 5vdc and used to charge or power USB devices.
Recipe from lasersaber on Youtube https://www.youtube.com/watch?v=Mzq_qWIhamQ
