Science-Fair Penny Volta Pile

My son and I did this 3-cell, 4-penny Volta pile for his 3rd grade Science Fair. His school is closed, so we're putting the project online.

Similar projects worth following
Since 1982, US pennies are made from pure zinc with a thin copper coating. If you polish off the copper coating on one side, you have the building block for a Volta pile. We used sandpaper, and lots of elbow grease, to expose the zinc core on the back of three pennies. With vinegar as electrolyte, and folded coffee filter as separator, our three-cell Volta pile had a voltage of almost 1.7 V, enough to light a red LED. I think I first saw this design on The King of Random YouTube channel.

This is a simple version of Volta's original pile from 1799, the very first electrical battery. Instead of sandwiching separate zinc and copper discs, we polish off the copper coating from the back of post-1982 US pennies, a trick we learned from The King of Random on YouTube. For a 3-cell battery you only need four pennies, three with the zinc core exposed on one side, and one intact (for the positive end of the pile). The pennies are separated by folded coffee filter soaked in household vinegar, which gives a cell voltage of about 0.55 V. This 3-cell penny Volta pile generated enough voltage to light a red LED!

Project video on YouTube!


Three post-1982 pennies, sandpaper, and lots of elbow grease!

JPEG Image - 69.50 kB - 06/09/2020 at 00:20



The zinc core is peeping through

JPEG Image - 74.72 kB - 06/09/2020 at 00:20



Seven minutes later, the copper coating is almost gone

JPEG Image - 82.70 kB - 06/09/2020 at 00:20



Dropping a penny with exposed zinc core into household vinegar to estimate self-discharge rate for a Volta pile with that electrolyte (found to be weeks)

JPEG Image - 28.54 kB - 06/09/2020 at 00:20



Different sandpaper grit. There was no obvious winner.

JPEG Image - 22.41 kB - 06/09/2020 at 00:20


View all 16 files

  • 4 × Post-1982 US pennies (zinc core with copper coating)
  • 3 × Coffee filters (or similar)
  • 1 × Household vinegar
  • 1 × Red LED

View project log

  • 1
    Remove copper coating from back of pennies

    Use regular sandpaper to remove the thin copper coating from three or four US pennies, minted after 1982. Newer pennies are made from pure zinc with a thin copper coating.

    There's about seven or eight minutes of sanding between the photo above and below.

    It took us about half an hour per penny. After three pennies it was getting dark, and we were out of patience, and expendable thumb nails.

    We heard somewhere that it's even harder to remove the copper on the front (heads) than the back (tails). Tails was hard enough.

    We tried both coarse and fine grit, but didn't see much difference.

    There must be a better way!

  • 2
    Make a separator for each cell

    We used AeroPress coffee filters for separators.

    Folded in half three times they become about the size of a penny.

    Trim off the excess paper.

  • 3
    Soak the separators in household vinegar

    We used pure household vinegar (5% acetic acid) as electrolyte. It is common to add some table salt (sodium chloride) to improve conductivity, and perhaps to mitigate partial passivation of the zinc anode. To keep the chemistry as simple as possible, we went with pure vinegar.

View all 5 instructions

Enjoy this project?



Johan Carlsson wrote 06/10/2020 at 00:57 point

Dan, thanks! Yes, it is a great project for a 3rd grader, and a good entry into science and technology. Electrochemistry is so visceral: hydrogen bubbles at the cathode, electrolyte changing color! I'm not going to lie though, sanding the copper coating off three pennies is hard work.

  Are you sure? yes | no

Dan Maloney wrote 06/09/2020 at 17:07 point

I remember doing the same experiment when I was about that age! Of course that's when pennies were copper through-and-through. IIRC, my dad gave me some galvanized washers for the zinc side of the cell.

  Are you sure? yes | no

Similar Projects

Does this project spark your interest?

Become a member to follow this project and never miss any updates