Make a Potato Battery to Power an LED Clock

Potato clock
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By
Anne Marie Helmenstine, Ph.D.
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
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Updated on March 31, 2019

A potato battery is a type of electrochemical cell. An electrochemical cell converts chemical energy into electrical energy. In the potato battery, there is a transfer of electrons between the zinc coating the galvanized nail that will be inserted into the potato and the copper wire that will be inserted another part of the potato. The potato conducts electricity, yet keeps the zinc ions and copper ions separate, so that the electrons in the copper wire are forced to move (generate current). It's not enough power to shock you, but the potato can run a small digital clock.

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Materials for a Potato Clock

You may have the supplies for the potato clock lying around the house already. Otherwise, you can find the materials for a potato clock in any hardware store. There are also pre-made kits you can purchase that contain everything you need except the potatoes. You will need:

  • 2 potatoes (or cut one potato in half)
  • 2 short lengths of copper wire
  • 2 galvanized nails (not all nails are galvanized or zinc-coated)
  • 3 alligator clip wire units (alligator clips connected to each other with wire)
  • 1 low-voltage LED clock (type that takes a 1-2 volt button battery)
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How to Make a Potato Clock

Here is what you need to do to turn the potato into a battery and get it to work the clock:

  1. If there is a battery already in the clock, remove it.
  2. Insert a galvanized nail into each potato.
  3. Insert a short piece of copper wire into each potato. Put the wire as far as possible from the nail.
  4. Use an alligator clip to connect the copper wire of one potato to the positive (+) terminal of the clock's battery compartment.
  5. Use another alligator clip to connect the nail in the other potato to the negative (-) terminal in the clock's battery compartment.
  6. Use the third alligator clip to connect the nail in potato one to the copper wire in potato two.
  7. Set your clock.
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More Fun Things to Try

Let your imagination run with this idea. There are variations on the potato clock and other things you can try.

  • See what else your potato battery can power. It should be able to run a computer fan. Can it light a light bulb?
  • Try substituting copper pennies for the copper wire.
  • Potatoes are not the only foods that can act as electrochemical cells. Experiment with lemons, bananas, pickles, or cola as a power source.
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Your Citation
Helmenstine, Anne Marie, Ph.D. "Make a Potato Battery to Power an LED Clock." ThoughtCo, Apr. 5, 2023, thoughtco.com/potato-battery-power-an-led-clock-606320. Helmenstine, Anne Marie, Ph.D. (2023, April 5). Make a Potato Battery to Power an LED Clock. Retrieved from https://www.thoughtco.com/potato-battery-power-an-led-clock-606320 Helmenstine, Anne Marie, Ph.D. "Make a Potato Battery to Power an LED Clock." ThoughtCo. https://www.thoughtco.com/potato-battery-power-an-led-clock-606320 (accessed April 18, 2024).