Making Food Batteries (Physics for ages 7+)

Imagine this: it’s a stormy night and the power goes out. You’re out of back-up candles and you can’t find any of your flashlights. What items in your home could you use to turn on a light bulb? There are probably some metal items that would conduct electricity pretty well, but would you have guessed your food could carry an electrical current?

It turns out many fruits and vegetables are able to carry electricity and have been used to create what is called a “food battery.” These batteries are not nearly as powerful as a normal battery, but it makes for some interesting scientific experimenting.

The video above shows us how to test the power of batteries made from a tomato, an apple, a lemon, a potato, a cucumber, an eggplant, and a banana. This experiment can be tested with any fruit or vegetable that you have at home. Here’s what you’ll need:


Materials Required:

Fruits and vegetables to test


Galvanized nail (zinc-coated)

Copper penny or wire

Knife (if using a penny)

Adult supervision (Adult supervision at all time please)

Before you get started, make some predictions, or hypotheses. Which food do you think will make the strongest battery (highest voltage)? Which one will make the weakest? Will all of the foods you’re testing carry the electrical charge? Be sure to keep track of your guesses so you can compare them to your results.



  1. First, poke your galvanized nail through the skin of the food you are testing.
  2. If you are using a penny, cut a small slit in the skin of the food to insert the penny a couple of inches away from the nail. If you are using copper wire, you should be able to poke it through much like the nail.
  3. Now it is time to test the power of your battery. Using the voltmeter (make sure it is in the right mode to test voltage), touch the red lead to the copper penny or wire (the positive pole) and touch the black lead to the zinc-coated nail (the negative pole).
  4. Record the number that the voltmeter shows. If the numbers are jumping around a lot, try to record the range from the lowest to highest readings.
  5. Repeat steps 1 through 4 for the rest of your food items.



So what is happening in your food, and if you eat it can the electricity hurt you? Firstly, no, the food will not give you an electric shock if you eat it because it is only transporting the electricity. Many of our foods contain electrolytes which are ions like sodium, chloride, and potassium.

These electrolytes are charged molecules and, when introduced to an electric current, will conduct the electricity. By adding the 2 metals and introducing the current (in the voltmeter), many foods are able to act as good electrical conductors.