I built a potato battery out of 500 pounds of potatoes. It powered a small sound system. With the help of the Red 76 crew I installed the battery and sound system in the back of a U-Haul truck and drove it around town inviting people to enter the truck and take a listen.
Batteries work by allowing electrons to pass from one electrode to another. In this case the potato provides phosphoric acid, which enables a chemical reaction causing electrons flow from copper to zinc. The zinc came from galvanized nails and copper came from small pieces of copper. You don't have to use potatoes; any acidic medium such as citrus fruit will work. I chose potatoes because they are traditional and cheap.
Each potato generates about 0.5 volts and 0.2 milliamperes. I connected groups of potatoes together in series to increase voltage and then connected these groups together in parallel to increase amperage. The entire 500 lb battery generated around 5 volts and 4 milliamperes.
Don't eat potatoes after using them for a battery.
Well we often have a discussion on potato farming in bags in your back garden. i run 3 sacks 30 days apart and get reasonable yeilds, enough for our use and every 30 days we get new batch. takes about 90 days to mature etc. Year round supply for very little effort.