My kids and I did this last year for a science project, sliced up an orange or grapefruit, stuck a copper wire on one side, and a dissimilar metal (steel, zinc, etc) on the other. Then we wired them in series and lit a 3volt LED. Each "cell" produced about 1/2 a volt.gspig said:A zinc rod and a copper rod driven into the ground is a simple battery. A zinc strip and a copper strip placed in a potato will power a small clock.
johnkl said:Wasn't Nicolai Tesla working on something like this?