This is a neat DIY project even kids can do. The voltage is so low it will hurt no one.
An AA battery has a diameter of .53" (14mm) and a length of 1.95" (49.7mm) including the top button. If fitting this into a device is important, try to get 13mm washers (outside diameter) so you will room for the shrink wrap. A US penny can be used but it's too wide at 18.9mm.
Modern US pennies since about 1984 have a zinc inside, and thin copper layer outside. So you can sand off one side of the penny to expose the zinc, and the other side will be copper.
Some questions to ask when making this:
- Does the voltage or amps produced depend on the surface area of the washers?
- What happens to the volts or amps if you change the electrolytes?
- Copper washers, 10x, from Hong Kong.
- Assorted copper washers various sizes, 200 pcs.
- Copper washers, 6mm inside diam, 10mm outside diam, 1mm thick. 10 pcs.
- Copper washers, 14mm outside diam, 10pcs.
- Copper washers, 13mm outside diam, 10pcs.
Zinc washers. (Galvanized washers means they are coated with zinc to resist rust.)
In various metric sizes.
- Washer dimensions.
- More metric washer dimensions (PDF).
- M6 washers have an OUTSIDE diameter of 11.5-16mm.
- M7 washers have outside diameter of 13.5mm.