Kids all over the country have learned how to make batteries from potatoes. I learned to do it when I was a kid. To be honest though, I thought it was just some sort of parlor trick my teacher learned from her colleagues. I was wrong.
Now in my fifties, I decided to look into the potato battery to learn exactly how it works. It is actually simpler than you might believe. A potato battery takes advantage of a chemical reaction between copper wire and the zinc coating of a galvanized nail.
To get the potato battery working you will need at least two potatoes. Pale Blue Earth, a Utah company that sells USB rechargeable lithium-ion batteries, says the potatoes perform the same function as the electrolyte in one of their rechargeable cells.
In addition to your two potatoes, you will also need:
- two pieces of copper wire
- two pennies (as clean as possible)
- one galvanized nail (you need the zinc).
You start by cutting a small notch in one of the potatoes. Then wrap one of your pennies in copper wire and insert it into the notch. Leave some of the wire protruding from the potato. Next, insert a galvanized nail into the opposite side of the potato. Half your battery is done.
Now, repeat the process with the other potato. When you’re done, connect the copper wire from one potato to the galvanized nail of the other one. You now have a working battery. If you were to connect a voltmeter between the open nail of the one potato and the copper wire of the other potato, it would register voltage. You could use your potato battery to power an LED light bulb.
Why It Works
Though potato batteries do not produce enough electricity to be worthwhile, they illustrate nicely how batteries actually work. As you know, potatoes don’t store electricity. Neither do copper wires, galvanized nails, or pennies. So what’s going on?
There are certain materials in both the galvanized nail and the copper wire/penny. When those materials come together, they create a reaction capable of producing electricity. That reaction needs a conduit through which ionic energy can flow. The potatoes act as the conduit.
In an actual battery, you have an electrolyte solution between the two ends of the cell. A lithium-ion electrolyte solution is based on lithium salts. The positive end of the battery is the cathode; the negative end is the anode. These two ends are comparable to the copper wire and zinc nail in your potato battery.
When those two ends come together in a closed circuit, they create a chemical reaction within the electrolyte solution. That chemical reaction generates electricity.
More Potato Batteries
Hopefully you now have a basic understanding of why the potato battery works and why it is a great illustration of how lithium-ion batteries work. But there is one more trick you can try. Grab a few more potatoes and use them to create additional battery setups. Connect them all in a single line – copper wire to galvanized nail.
When you’re all done, check them with your voltmeter. You should notice a higher reading than you got with just two potatoes. Indeed, every potato you add to the series increases the voltage.
Potato batteries really do work. It may seem primitive but building such a battery is a helpful way to grasp what goes on with the batteries that power our cell phones, flashlights, and electric toothbrushes. Batteries really aren’t so complicated when you break them down to their basic components.