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How to Make a Battery

The inner workings of a battery are actually quite simple. All you really need is an electrolyte solution and some conductive material for the electrons to flow to and from. Copper and zinc are the most common metals used for this kind of circuit.

Home-made batteries aren’t as efficient as the ones you buy in the store, but they have the potential to power small devices. As for the electrolyte solution, that can come from a variety of household items. Let’s look at some of the most popular methods for making a battery at home!

How to Make a Battery from Coins

What you’ll need:

  • 5-10 copper or zinc coins
  • Aluminum foil
  • Cardboard or paper
  • Towel or washcloth
  • Bowl of water
  • Salt
  • Vinegar
  • Copper wires
  • Sandpaper (optional)

Most US coins have copper in them, which is a highly conductive metal. Copper makes up 75% of a modern nickel and roughly 91% of a modern dime or quarter. Pennies made before 1982 are 95% copper, while those made from 1983 and after use zinc cores with a copper coating. 

how to make a battery
Coin battery can be quite a fun project

You can use any of these coins to make a battery, although pennies and quarters tend to be the most effective. If you’re using zinc pennies, prepare them first by sanding the copper coating off of the tails side. In this case, you won’t need the aluminum foil.

  1. Add salt to the bowl of water and stir. Keep adding until the mix is completely saturated and the salt will no longer dissolve, then add a splash of vinegar. 
  2. Cut as many pieces from the cardboard or paper as you have coins. They don’t have to be perfect, but you should make them roughly the same size as the coins. 
  3. Soak the paper or cardboard in the water mixture, then remove them and set them on the towel. You want the circles to be damp but not dripping.
  4. Cut as many pieces from the aluminum foil as you have coins. 
  5. Stack the pieces together. Start with a piece of foil, then the coin, and finally the wet cardboard. If using zinc pennies, start with a penny (tails up) then put a piece of cardboard on top of it.
  6. Continue stacking in this order until all the pieces are used, making sure none of the coins or pieces of cardboard are touching each other.
  7. Attach wires to either side of your stack.

A battery made this way will last as long as the cardboard stays wet, though it will lose strength as the cardboard dries. 

How to Make a Potato Battery

What you’ll need:

  • A large, fresh potato, washed free of dirt
  • 1 galvanized nail
  • 2 alligator clips
  • 1 copper coin
  • Copper wire

In a potato battery, the water inside the potato takes the place of the solution used in the coin battery. The fresher the potato is, the more moisture it will contain, and the better the battery will work. 

  1. Push the nail into the potato until it’s almost (but not quite) poking out the other side. If you punch through the far side, just pull it back so the point isn’t sticking out.
  2. Stick the coin into the potato close to the nail, but not touching it. The closer the nail and coin are, the higher the voltage of your battery. If they touch, though, they’ll short-circuit and the battery won’t work.
  3. Attach one alligator clip to the nail, and the second to the coin.
  4. Attach a copper wire to each alligator clip.

One potato battery won’t generate too much voltage, but you can link them together in sequence using multiple copper wires to generate electricity equivalent to a button (3-volt) battery. 

How to Make a Lemon Battery

What you’ll need:

  • 1 lemon
  • One galvanized nail
  • 1 copper coin
  • 2 alligator clips
  • Copper wire
  • Knife for cutting

If you don’t have a galvanized nail, you can substitute a piece of aluminum foil. The concept of the lemon battery is much the same as the potato battery above. Lemons are even more effective, though, since the acid in the juice makes it more conductive.

  1. Squeeze the lemon to release its juices inside, being careful not to break the skin. 
  2. Cut a small slit in the lemon’s rind, large enough to insert the coin (2 slits, if you’re using aluminum foil rather than a nail).
  3. Insert the coin into the slit, and push the nail into the lemon a short distance away but not touching (or put the foil in the other slit). Make sure both are deep enough they have physical contact with the juice inside the lemon.
  4. Attach one clip to the nail, and the second to the coin.
  5. Attach a copper wire to each clip.

How to Make a Salt Water Battery

What you’ll need:

  • A strip of a firm, non-conductive material (plastic works best)
  • 6 long galvanized nails
  • 6 strips of paper
  • Copper wire
  • Salt
  • Vinegar
  • Water in a non-conductive container (no metal)
  • Hammer

If your copper wire is insulated, you’ll need to strip off the insulation first. The sandpaper can be helpful in doing this. Make sure your container is large enough for the strip of plastic to fit inside. 

  1. Wrap each nail with a piece of paper, then coil copper wire around the paper. Make sure the wire doesn’t touch the nail or you’ll have a short-circuit. Leave enough space at the bottom of the nail to secure them in the non-conductive strip.
  2. Hammer the nails into the non-conductive strip until they’re secure. Space them far enough apart that the nail heads don’t touch. Use more copper wire to connect the nail heads in sequence.
  3. Make an electrolyte solution by adding salt and vinegar to the water. The ratio should be roughly 1 teaspoon salt and 1 teaspoon vinegar per 6 ounces of water. Stir until dissolved.
  4. Put the strip of nails into the solution, making sure they’re not fully submerged.
  5. Connect a copper wire to each end of the nail strip.

You can add more nails to increase the power, or add a bit of bleach to your electrolyte solution.

Final Words

Commercial batteries have an obvious size advantage over home-made versions. To produce the 3 volts generated by a watch battery, you’ll need roughly 6 potatoes, 4 lemons, or a stack of 6 coins. Still, it’s pretty cool to create power using common household items! We hope you feel inspired to try out one of these battery projects for yourself. 

Bonus: Check out our guide on changing battery in key fob!

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