How can I light up an LED with potatoes?

Open navigator

1. Energy efficient light

Traditional incandescent light bulbs need a huge amount of energy to make a small amount of light – because much of their energy is lost as heat. But engineers have found ways to produce useful amounts of light in a totally different way .

LEDs, or light-emitting diodes, need tiny amounts of energy to light up. To prove the point, you can even get one lit with just a few potatoes. Follow my step-by-step instructions to make a vegetable powered light and see for yourself.

2. Build a potato-powered battery

Follow these simple steps to create a potato battery that can light up an LED.

LEDs just need a tiny bit of electricity to turn on – something you can produce with a potato, a coin and a nail.

You’ll need three potatoes, galvanised nails (coated in zinc), copper coins, crocodile clips, copper wire, scissors, a knife and an LED. Small LEDs that only need 1 or 2mA of current to run, or red LEDs, tend to work the best.

Insert a copper coin into one end of a potato and a nail into the other. For the coin, it might help to use a knife to score the potato first. Repeat this for each of the three potatoes.

Cut out four pieces of wire around 15cm long. With each piece, remove the plastic insulation from both ends using scissors to expose around 3cm of the copper wire.

Wrap one end of the wire around the top of a crocodile clip, ensuring good contact between the exposed copper and the metal clip, then clip this onto the coin wedged into the potato. Repeat this with three of the wires.

Wrap the exposed copper ends of two of the wires around the nails of the neighbouring potatoes. Take the fourth piece of wire and wrap one end around the last free nail. You’ve now set up your potato battery.

The coin is the positive end of your battery and the nail is the negative end. If you've got access to a multimeter, you can check how the battery performs, by connecting the free wires; coin end to the red probe and nail end to the black.

Use your potato battery to light up an LED. Wrap the free wire at the coin end around the long leg of the LED and the free wire at the nail end around its short leg. Be careful not to let the two copper wires touch each other directly.

The LED should light up, especially if it's a small one or a red LED, both of which require less current to work than other LEDs.

Lighting up other LEDs might take more potato power. Make six 'three-potato' batteries. Connect all six wires from the coin ends together, and all six wires from the nail ends together. Use two extra wires to connect these bunched ends to the LED.

3. How it works

Click on the labels below to find out how the potato battery works.

This content uses functionality that is not supported by your current browser. Consider upgrading your browser.

4. What’s the best power plant?

Danielle 1024x768.jpg

Potatoes aren’t the only things that can power an LED. Try making a battery with these fruits and vegetables by connecting three of them together. Which one lights up your LED the brightest?

5. What results did we get?

Which plant powered battery worked best for us? We used a multimeter to measure the voltage of each one.

Potatoes

You selected

Potatoes

2.66 volts

Three potatoes generated over 2.5 volts when connected together.

Bananas

You selected

Bananas

1.42 volts

The unripe bananas gave less than 1.5 volts, which may be because bananas are less acidic than the other foods.

Tomatoes

You selected

Tomatoes

2.46 volts

The tomatoes tested were very ripe and watery, which may have contributed to their conductivity.

Lemons

You selected

Lemons

2.74 volts

Lemons gave the highest voltage. They are also the most acidic of all the foods tested.