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How to Build a Lemon-Powered Clock

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Power a digital clock by making a battery out of lemons.


  • 2 ripe lemons
  • Low-voltage digital clock (Use a clock that takes one AA battery or a 1.5-volt button cell battery. One AA battery has about 1.5 volts of energy. Two lemons should produce about 1.5 volts.)
  • 2 copper pennies (If your penny has a date before 1982, it is made of 95 percent copper. If the date is 1982 or later, it is made of 97.5 percent zinc with a thin copper coating. The old pennies work better.)
  • 3 8″ lengths of copper wire
  • 2 galvanized nails (Galvanized nails are coated with zinc.)
  • Knife
  • Scissors
  • Clip leads (alligator clips), optional


1. Roll the lemons on a hard surface, being careful not to break the skin. (This will loosen the pulp, make the lemons juicy and help the electrons move through the lemons.)

2. Wrap one end of a wire around a penny and the other around the end of a nail. (These will be used to connect the lemons together. Connecting lemons with metal wires adds voltage from each lemon. The more lemons you connect together, the higher the voltage.)

3. Connect a second wire to a penny and leave the other end bare.

4. Wrap the third wire around a nail and leave the other end bare.

5. Cut a slit in each lemon just large enough to insert the pennies. Insert the pennies and nails as shown in the image at the top of this page. (Make sure the copper wire has good contact with both the pennies and nails, and make sure the pennies and the nails make good contact with the lemon pulp and juice.)

6. Remove the battery from the clock and touch the wires to the positive and negative terminals in the clock. If your clock doesn’t work, try switching the wires.

7. You can also use clip leads (alligator clips) to connect your wires to the pennies, nails and clock, as shown below.


Check out these photos of completed lemon-powered clocks sent to us by Boys’ Life readers. If you have a photos of a BL Workshop project, please use the form below to send them to us.

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12 Comments on How to Build a Lemon-Powered Clock

  1. Why do we need the wire connecting the penny and nail? Can you please explain? Why can’t we just connect the positive and the negative of the battery to two different penny and nail and insetr them into the same lemon? The circuit will still be complete right??

    • Whoop whoop! // February 12, 2017 at 9:55 pm // Reply

      Each piece of fruit is a single cell in your fruit battery. In order to connect the cells and produce more volts you need to use the additional second metal in each fruit and clip them together to complete the circuit.

  2. disapointed // May 4, 2016 at 5:18 pm // Reply

    mine didn’t work

  3. Sadly Disappointed // February 2, 2016 at 7:58 pm // Reply

    Tried this experiment with two lemons, (no clips) everything else per the list and no success! Students will have to brainstorm and come up with reasons why it did not work!

  4. still hasn’t worked

  5. Can we use regular low voltage clocks because I cant find any low voltage digital clocks, i used other clocks that weren’t digital they didn’t work though

  6. thecrazylemon // December 21, 2015 at 3:27 pm // Reply

    I did this for my science fair and I got first place so WHOO HOO!

  7. it will work

  8. BlackOps2ShotgunMaster // October 20, 2015 at 7:42 pm // Reply

    This is a pretty good project to do, sometimes though if the lemons don’t produce enough voltage the clock might not work. That’s the only downside to the experiment.

  9. This did’t work for me. I first tried it with the lips. Don’t work. Then, the regular way. Didn’t work.

  10. cool

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