Potato Battery Experiment: Powering a Light Bulb With a Potato

A little girl holding her hand over a lit light bulb, while laughing with her dad. — A potato is not only food; it can also emit low currents of electricity. Peter Cade / Getty Images

Did you know you could power a light bulb with a potato? The chemical reactions that take place between two dissimilar metals and the juices in the potato create a small amount of voltage that can power a very small electrical device [source: MadSci].

Follow the instructions below to make a potato battery.

Contents

How to Make a Potato Battery
The Science Behind Potato Battery Experiments
Using Potato Batteries to Power Other Devices

How to Make a Potato Battery

Materials:

One potato (ideally large)
Two pennies
Two galvanized nails (zinc-plated nails)
Three pieces of copper wire
A very small light bulb or LED light

What You Need to Do:

Cut the potato in half, then cut a small slit into each half, large enough to slide a penny inside.
Wrap some copper wire around each penny a few times. Use a different piece of wire for each penny.
Stick the pennies in the slits you cut into the potato halves.
Wrap some of the third copper wire around one of the zinc-plated nails and stick the nail into one of the potato halves.
Take the wire connected to the penny in the half of potato with the nail and wrap some of it around the second nail. Stick that second nail into the other potato half.
When you connect the two loose ends of the copper wires to the light bulb or LED, it will complete the electrical circuit and light up.

Be careful when handling the wires, because there is a small electric charge running through the wires. Hydrogen gas may also be a byproduct of the chemical reactions in the potato, so don't perform the experiment near open flames or strong sources of heat [source: MadSci].

The Science Behind Potato Battery Experiments

Batteries store energy for later use, but where does the energy come from? All batteries rely on a chemical reaction between two metals.

In a potato battery, the reaction — between the zinc electrodes in the galvanized nails, the copper in the penny, and the acids in the potato — produces chemical energy.

The potato doesn't produce electricity, but it does allow the electron current to flow from the copper end to the zinc end of the battery.

Using Potato Batteries to Power Other Devices

You can try using multiple potatoes to power other battery-equipped devices, like a clock.

In the battery compartment, connect the potato with a copper coin inside to the positive terminal (marked with a "+") and a potato with a galvanized nail inside to the negative terminal (marked with a "-"). Learn more about how to make a potato clock.

With any potato battery experiment, if your battery doesn't power your device on the first try, you can try increasing the number of potatoes. You can also use other fruits and vegetables to make batteries — lemon, which is highly acidic, is a popular choice.

Sources

"Food Batteries." MadSci Network. Mar. 14, 1998. (Sep. 20, 2023). https://www.madsci.org/experiments/archive/889917606.Ch.html

Potato Battery FAQ

How does a potato battery work?

Potatoes contain acids, which start a reaction allowing electrons to flow between two metal points. The potato acts as a salt bridge that connects the anode and cathode, releasing salt ions to help generate electrical energy.

Can a potato light up a light bulb?

If you want to power high-voltage bulbs, then the answer is no. A potato battery generates roughly 0.5 volts of energy, which is only enough power to light up a low-voltage LED.

Why does my potato battery not work?

Check your wires and connections. Use copper as an anode and zinc as a cathode. A lot of people use steel nails, which doesnâ€™t work, so be sure youâ€™re using a nail with a zinc coating. Donâ€™t connect loose wires to the electrodes. Instead, use alligator clips for a secure connection.

How many amps of energy can a potato battery produce?

A single potato battery can produce about 0.2 milliamperes of current and 0.5 volts. However, you can increase the power by connecting multiple potato batteries together in a series if you want more voltage.

Does using a boiled potato result in more power?

Yes, researchers claim that you can increase the power output of a potato by boiling it for about eight minutes. Boiling breaks down the organic tissues inside potatoes and shrinks resistance, allowing electrons to flow more easily and generate more power.