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Build a lemon-powered clock

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

WHAT YOU’LL NEED

  • 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

WHAT YOU’LL DO

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.

85 Comments on Build a lemon-powered clock

  1. Bookworm for real // May 12, 2014 at 11:57 am // Reply

    I liked it very much
    K

  2. i’m doing it for my science fair

  3. Thanks this helped

  4. thanks I got a A+ on my science project

  5. do you need gloves to put the pennies or nails in??

  6. My fith grade project

  7. OMG OMG OMG OMG OMG did not work

  8. my science fair is in 6 days what do i test for this

  9. i cant wait 2 make it!

  10. im so gonna make it if you say it works

  11. amazing cool

  12. I am so growing a lemon tree

  13. cool but i like it

  14. cassie bug // June 16, 2013 at 1:47 pm // Reply

    this has been helpful (:

  15. I think that the blog is interactive, and the projects are interesting.
    I LIKE IT.

  16. awesome95 // May 12, 2013 at 2:33 pm // Reply

    AWESOME!!

  17. it is cool

  18. it is helpful yet very very confuseing ;(

  19. awesome kid5000 // May 5, 2013 at 11:45 am // Reply

    awesome no more batteries!!!!!!!!!!!!!!!!!!

  20. XxcrazySAUSAGE // April 9, 2013 at 9:14 am // Reply

    im making it

  21. it works

  22. cool

  23. I doing it for my science fair project cool magazine even though Im not a boy im a girl

  24. laugh out loud // March 27, 2013 at 5:05 pm // Reply

    my 4th grade project

  25. I am going to try this for my science fair

  26. it really works

  27. dose it have a alarm

  28. it really works i tried it and i still use it

  29. ME!!!!!!!!!! // January 23, 2013 at 6:09 pm // Reply

    look’s pretty cool i’ll use it for the science fair if i don’t eat the lemons first XDXDXD

  30. look’s preety cool thanks!!!

  31. PRETTY COOL GOOD 6TH GRADE SCIENICE PRJECT

  32. lj coool man // January 16, 2013 at 4:36 pm // Reply

    awsome cool

  33. Thank You Very much. I am going to use this for my visual presentation in my 5th grade class!

  34. im using it for my science fair tommorow

  35. Science fair project material

  36. do we need nails or what?

  37. yay im using this in my science fair which is tomorrow

  38. how much will be the voltage of this??
    can we use this to charge phone?

  39. it really works

  40. i am gonna try this

  41. supersayian4freak // October 12, 2012 at 7:42 pm // Reply

    Looks awesome! I’d do that!

  42. awsome dude // October 6, 2012 at 5:33 pm // Reply

    Does this have to do with the acid in the lemon?

  43. awsome dude // October 6, 2012 at 5:31 pm // Reply

    I think this is a way better way to power my clock.

  44. im using this for my science far project but i modified

  45. this is very cool mamby it could get me a good grade in the science fair

  46. Will you please describe the mechanism behind it? I don’t understand the reason behind copper and zinc plate. Is there any idea behind it? And in step 2, why the two lemons were joined by a single copper wire?

    • If you dont complete the circuit, then it wont work! Meaning, if lemon 1 is connected to nail 1, positive end, and penny one, and lemon 2 is connected to nail 2, penny 2, and negative end, but the two lemons have no OBVIOUS connection, then the circuit is incomplete, like putting bread in the toaster and turning it on, but you didn’t plug it in or put in batteries, then it wont work.

  47. Amazing! Really works and also made one out of orange!

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