FRUIT BATTERIES

About the Activity

Fruit bowls are brimming with way more than just delicious flavor – they also have potential electricity. That’s because each fruit can be a key component in a homemade battery. This 4‑H STEM Lab activity teaches kids the key parts of a battery and the chemical reaction that makes it possible! Kids can even try to break a Guinness World Record (instructions are included below).

 

Grades: Pre-K – 2
Topic: Electricity
Estimated Time: 30 minutes

 

Brought to you by Guinness World Records

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Supplies
These simple materials—along with a few specialty supplies—will get you started.

Some of these you’ll have at home, some you may need to order or get from a hardware store.

  • Pennies
  • Galvanized (zinc-coated) nails/li>
  • Citrus fruit (lemons, oranges, limes)
  • Alligator clips
  • LED bulb
  • Voltmeter
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Activity Steps

The following steps can be used to make a battery with the help of fruit, but you can also try experimenting with different types of fruit and different metals for electrodes.

 

First, we all know what a battery does, but what is it, exactly? A battery is anything that converts chemical energy directly into electrical energy. So, it doesn’t have to be the AA battery that is in your remote control, it can be lots of things – including a lemon and a penny and a nail that are interconnected. Okay, let’s get started.

 

  1. First, use your hand to lightly roll your lemon against a flat surface to make sure the insides are extra juicy.Did You Know? Lemons aren’t the only fruit or vegetable that can generate and conduct electricity. Potatoes and pickles are also great at conducting electricity. Oranges and tomatoes? Not so much. 
  1. Next, carefully use a knife or scissors to cut two slots/holes in opposite ends of the lemon.
  2. Insert the copper penny into one of the holes you just cut, and the zinc nail into the other one. (If you’re doing this for Guinness World Records™, you’ll start the time at the beginning of this step.)Did You Know? Let’s get something clear – the lemon isn’t producing the electric current, it is conducting it. The penny and nail have different amounts of electrical charge within them, and when they are connected by something that can conduct that energy, those charges flow back and forth. In this case, that conductor is the lemon.
  3. Connect the nail and the coin (your electrodes) with the alligator clips. Make sure that one end is attached to the nail and the other to the coin.Did You Know? Lemons are able to conduct electrical current because they are high in electrolytes. Electrolytes are essential minerals that, in the human body, are vital to many key functions, and are found in many foods. Electrolytes are also capable of carrying electric current. Pickles also make great batteries because they are soaked in a salty brine – and salt water is full of electrolytes.
  4. Once you’ve joined up the lemon battery you should be left with two free clips at either end – one coming from the nail and the other coming from the coin.
  5. To complete the circuit, attach the clips to the LED.Tip: If you hook up the LED and it doesn’t glow, switch the two alligator clips on the LED around.

Bonus Fun:
Go for a Guinness World Record for the fastest time to put together a fruit battery! Click here for the full details on the challenge.

4-H STEM Lab Bonus Fun Fruit Battery

Reflection Questions
Questions to deepen wonder and understanding.

  1. How many pieces of fruit were needed to power one LED?
  2. What did you observe? Are there any changes in the fruit?
  3. Try substituting a lemon for a different piece of fruit. What difference does this make to the battery’s performance?
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Investigate and Explore
Take your new knowledge to the next level.

Bio batteries work because two different metals suspended in an acidic solution create a chemical reaction that generates electricity. All batteries (including bio batteries, like the one you’ve just made) consist of three key parts: a cathode (the positive end of a battery), an anode (the negative end of a battery) and an electrolyte solution (the medium that allows the electric charge to flow between the cathode and anode).

4-H STEM Lab Activity: Fruit Battery

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