STEAM NightStation operators · prep and learn

🥔 Potato Batteries

Power a light with potatoes. Draft: not yet checked

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Watch how it is done

Two short videos. Tap one to play it.

  1. Now playingPotato BatteryTheDadLab
  2. Now playingLight Up an LED with PotatoesBinghamton University

Videos play from YouTube, made by other people.

Quick start

  1. Find the chain of potatoes, already wired.
  2. Clip the last wire to the LED.
  3. Look into the tube to see if it lights.
  4. Swap the two LED clips and see what happens.

Ask, instead of explaining: What do you think happens if we swap the clips?

Learn: the idea

Two different metals stuck in a potato make a tiny battery. The potato juice carries charge between the metals, and the current flows around the loop of wire. Hook a few potatoes together and you get enough power to light an LED.

Prep
  • Wire the chain: zinc and copper in every potato.
  • Put the LED inside a cardboard tube.
  • Leave only the last connection for the kid.

Crew for prep: 1 person, about 1 hr. Prep happens on the day, from 12:15.

During the event: 2 volunteers. Setup about 30 min. Plus a challenge-giver for older kids

Tips

  • Pre-build the chains. Leave the zinc and copper already in the potatoes, with the clips connected between them. Keep only the last one or two connections for the kid to make.
  • Put the LED in a toilet-paper tube so kids can see the glow in daylight. "Look in the tube!"
  • Have two volunteers. One gives older kids a challenge: "What happens if you swap the clips?" (An LED only works one way.)
  • Keep a fruit version (lemons) to the side.
  • Cut potatoes in half to double the number of cells. Replace them only when they dry out.
Safety
  • Kids touch only the clips: LED legs are sharp.
  • Nobody eats the experiment potatoes.
  • Wash hands afterward.
Turbo (only if we choose to)
  • Can we charge a phone? Not with potatoes: each potato makes only about 0.5 to 1 volt and a tiny current. Instead, let a kid crank a hand-crank USB charger on an old spare phone, then ask: how many potatoes would that take?
  • Build a mega chain of about 10 potatoes to run a small digital clock as the centerpiece.
  • Human battery: kids hold hands in a chain between a copper plate and a zinc plate wired to a cheap analog meter, and the needle moves.
Clean up
  • Wipe the table and put reusable items in your tote.
  • Bag the trash and wash hands.
  • Log anything borrowed so it can go back.