How to make a lemon battery

This activity is part of our Science Lab series. Check out the ANU Science Lab for more experiments! In this activity, you will construct a simple battery using lemons, copper strips, and galvanized nails to explore electrochemistry, voltage, series vs parallel circuits, and electric currents. Watch the video above to see how it is done.

Lemon battery experiment materials & ingredients

For this activity:

• 4 to 5 fresh lemons (or other citrus fruits)
• 4 to 5 strips of copper wire or copper sheet (positive electrode)
• 4 to 5 galvanised steel nails, which are zinc-coated (negative electrode)
• Electrical jumper leads with alligator clips (or thin copper wire and pliers)
• 1 low-voltage LED light bulb
• Digital multimeter (to measure voltage and current)

Safety Note: Do not consume the lemons after inserting metal nails and copper wire into them.

How to make a lemon battery: Step-by-step instructions

Step 1: Create individual lemon cells

1. Roll each lemon firmly on a table with your palm to break the internal juice vesicles without breaking the skin.
2. Push one galvanised steel nail into one side of a lemon.
3. Push a copper strip into the opposite side of the same lemon, making sure the metal pieces do not touch each other inside the fruit.

Step 2: Connect cells in series

1. To build up enough voltage for an LED, connect your lemon cells in a series circuit.
2. Connect an alligator clip lead from the copper strip (positive) of Lemon 1 to the galvanized nail (negative) of Lemon 2.
3. Repeat this pattern across all 4 or 5 lemons until you have one free copper terminal at one end and one free nail terminal at the other end.

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Step 3: Test voltage and light the LED

1. Attach a digital multimeter across the free end terminals to measure your battery. A 4 to 5 lemon series setup will generate approximately 2.5 to 3.0 volts.
2. Connect the long wire of your LED light bulb (positive anode) to the free copper terminal, and the short wire (negative cathode) to the free nail terminal.
3. Dim the room lights to watch your LED glow powered entirely by lemons!

How a lemon battery works: The science explained

This demonstration illustrates redox (reduction oxidation) reactions and circuit configurations:

• The lemon does not contain electricity itself. Instead, the acidic lemon juice (citric acid) acts as an electrolyte.
• Zinc on the galvanised nail undergoes oxidation, losing electrons and releasing zinc ions into the acid. Electrons travel through the external wire toward the copper strip, generating an electric current.
• Connecting positive copper to negative zinc across multiple lemons combines their potential energy, boosting total voltage (e.g. 0.8 V + 0.8 V + 0.8 V = 2.4 V).

Science fair projects & taking it further: Experimenting with variables

• Test limes, potatoes, bananas, or salt water. Which natural electrolyte produces the highest voltage reading on a multimeter?
• Swap out copper and zinc for aluminium foil or iron paperclips. Which combination of metals creates the largest voltage difference?
• Warm up one set of lemons and chill another in the fridge. Does temperature affect the rate of chemical reaction and current output?

Enjoyed this experiment? Explore more hands-on activities on the Science Lab ANU YouTube channel.