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Make a Penny Battery

Make a Penny Battery
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Make a simple penny battery using pennies, zinc washers, saltwater-soaked cardboard, and an LED to learn basic electricity and battery principles hands-on.

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Step-by-step guide to make a penny battery

What you need
Adult supervision required, cardboard, led, paper towel, pennies, salt, scissors, small bowl or cup, spoon or stirring stick, tape, water, zinc washers

Step 1

Pour about 1/4 cup of water into a small bowl.

Step 2

Add one teaspoon of salt to the water.

Step 3

Stir the water with a spoon until the salt dissolves.

Step 4

Cut four cardboard circles the size of a penny using scissors.

Step 5

Soak each cardboard circle in the saltwater for 5–10 seconds.

Step 6

Place one penny on a flat table or countertop.

Step 7

Put one soaked cardboard circle on top of the penny.

Step 8

Place a zinc washer on top of that cardboard circle.

Step 9

Repeat placing penny then soaked cardboard then zinc washer until you have 4–6 cells and the top piece is a zinc washer.

Step 10

Wrap a small piece of tape around the stacked cells to hold them together snugly.

Step 11

Pick up the LED and identify the longer leg as the positive leg and the shorter leg as the negative leg.

Step 12

Press the longer (positive) LED leg gently onto the copper penny at the bottom of the stack.

Step 13

Press the shorter (negative) LED leg gently onto the zinc washer at the top of the stack.

Step 14

Tape both LED legs so they stay touching the metal surfaces and the LED can get power.

Step 15

Share a photo and what you learned about your penny battery on DIY.org.

Final steps

You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!

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Help!?

What can I use if I can't find zinc washers or pennies?

If you can't find zinc washers, substitute a zinc‑plated screw, galvanized nail, or zinc nut as the top metal, and if pennies are unavailable use a small flat copper coin or a scrap of copper so the longer LED leg can touch copper at the bottom of the stack.

My LED won't light — what should I check and how can I fix it?

Check that each cardboard circle was soaked in the saltwater (1 teaspoon salt in 1/4 cup water) for 5–10 seconds, confirm the stack has alternating penny/cardboard/zinc washer cells with the penny at the bottom and zinc washer on top, make sure the longer LED leg touches the bottom penny and the shorter leg touches the top zinc washer, and tape the stack snugly so metal surfaces have good contact.

How can I adapt this activity for different ages?

For younger children have an adult pre‑cut the cardboard circles, help with scissors and tape, and build a simpler 2–3 cell stack for a quick demo, while older kids can assemble 4–6 cells, record voltages with a multimeter, and experiment with different metals or LED types.

How can we improve or personalize the penny battery experiment?

To enhance the activity try increasing to 6 cells for a brighter LED, combine two stacks in series or parallel on a piece of cardboard to compare outcomes, and personalize by decorating the taped stack or testing different LED colors.

Watch videos on how to make a penny battery

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"Science Fair: Penny Battery" by Adventure Academy

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Facts about basic electricity and batteries

🔋 A copper–zinc cell (like a penny touching zinc) typically produces about 0.6–1.1 volts — stack cells to get more voltage!

🧪 Alessandro Volta built the first true battery, the voltaic pile, in 1800 — penny batteries are a tiny, kid-friendly version of that idea.

💡 LEDs are picky about polarity and voltage — some LEDs need several stacked penny cells before they will light.

🪙 Most modern U.S. pennies are mostly zinc with a thin copper coating — the zinc core is what reacts in penny batteries.

🧂 Saltwater-soaked cardboard acts as the electrolyte, letting charged ions move between the metals so current can flow.

How do I make a penny battery at home to light an LED?

To make a penny battery, cut cardboard into small discs and soak them in saltwater (about 1 tsp salt per 1/2 cup water). Clean pennies if dirty. Stack cells by placing a penny (copper side up), a soaked cardboard disc, then a zinc washer. Repeat to build several cells in a column. Attach the LED by connecting its longer lead to the top copper penny (positive) and the shorter lead to the bottom zinc (negative) using tape or clips.

What materials do I need to make a penny battery with an LED?

You’ll need clean pennies, zinc washers (or galvanized washers), small cardboard discs or thick paper, salt, water, scissors or a hole punch, an LED (low-voltage like red or yellow), tape or alligator clips, tweezers, small bowls, and paper towels. Optional: a multimeter to measure voltage and safety gloves. Avoid using household batteries or acids; stick to the simple saltwater electrolyte.

What ages is the penny battery activity suitable for?

This activity is best for children about 7 years and up with adult supervision, since it requires fine motor skills and understanding of polarity. Younger kids (4–6) can help prepare materials and assemble stacks with close adult help. It’s not suitable for children under 3 due to small parts and choking hazards. Older kids can experiment with more cells and measuring voltage.

Is making a penny battery safe for kids and what precautions should I take?

Adult supervision is required. Small parts are choking hazards, so keep pennies and washers away from very young children. Don’t swallow saltwater or components. Avoid shorting the stack—don’t let copper and zinc touch across a conductor except through the LED. Rinse hands after handling and dispose of wet, corroded pieces properly. If skin irritation occurs, stop. Never connect this setup to mains power or strong chemicals.
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Make a Penny Battery. Activities for Kids.