BL Workshop

Build a lemon-powered clock

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.


Comments about “Build a lemon-powered clock”

  1. Bookworm for real says:

    I liked it very much

  2. Brandon says:

    i’m doing it for my science fair

  3. Jimmy says:

    Thanks this helped

  4. cam says:

    thanks I got a A+ on my science project

  5. googie says:

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

  6. ajjaj says:

    My fith grade project

  7. SAYS says:

    OMG OMG OMG OMG OMG did not work

  8. swag says:

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

  9. me says:

    i cant wait 2 make it!

  10. fart man says:

    im so gonna make it if you say it works

  11. love says:

    amazing cool

  12. lilipup says:

    I am so growing a lemon tree

  13. lily been says:

    cool but i like it

  14. cassie bug says:

    this has been helpful (:

  15. STEVENS says:

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

  16. awesome95 says:


  17. poo says:

    it is cool

  18. poo says:

    it is helpful yet very very confuseing ;(

  19. awesome kid5000 says:

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

  20. XxcrazySAUSAGE says:

    im making it

  21. iuiu says:

    it works

  22. kyla 565 says:


  23. kimmy says:

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

  24. laugh out loud says:

    my 4th grade project

  25. lala land says:

    I am going to try this for my science fair

  26. shasha says:

    it really works

  27. c.s says:

    dose it have a alarm

  28. GameBoss101 says:

    it really works i tried it and i still use it

  29. ME!!!!!!!!!! says:

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

  30. me says:

    look’s preety cool thanks!!!

  31. xxinfamous says:


  32. lj coool man says:

    awsome cool

  33. JOJOJOJOJO says:

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

  34. owen says:

    im using it for my science fair tommorow

  35. Owenie says:

    Science fair project material

  36. beedub says:

    do we need nails or what?

  37. aussa5 says:

    yay im using this in my science fair which is tomorrow

  38. sethvrushus says:

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

  39. spider man says:

    it really works

  40. troop21 says:

    i am gonna try this

  41. supersayian4freak says:

    Looks awesome! I’d do that!

  42. awsome dude says:

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

  43. awsome dude says:

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

  44. bossaru says:

    im using this for my science far project but i modified

  45. t.d tommy says:

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

  46. udoy says:

    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?

    • Adawg says:

      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. Cat Fan 84 says:

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

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