Potato and Lemon Batteries

Materials Needed:

Potatoes or Lemons:
Function: Acidic Chemical to support flow of charge
Positive and Negative metals
Nail- zinc- Negative charge
Penny- copper= positive charge
Voltage Meter
measure how much voltage is produced by each lemon

We will be conducting an experiment to discover how many lemons or potatoes it takes to light up a LED.


In the last lesson we built the simple LED circuit.

LED circuit schematic diagram

A Circuit is path that allows electricity to flow through.
A LED stands for Light Emitting Diode, which is a special type of light that only allows electricity to flow in one direction.
In this lesson we will study how the Battery works.


1) Stick 1 nail and 1 penny into the first lemon
2) Measure the voltage by Making sure that the Penny (Positive) is connected to the red wire of the meter, and the nail (negative) is connected to the black wire of the meter
3) Connect the battery wires to an LED and test whether or not it lights up.

The LED will most likely NOT light up with just one lemon, so we will need to add more!

We will be creating a series circuit by connecting several lemon batteries together. The series circuits adds the voltages of each battery together. Measure the voltages and add them up.
REMEMBER plus and minus matters so always connect a positive ( penny) to a negative (nail). Check all connections to make sure that the electricity can flow through a complete circuit from positive through you LED and back to negative .

4) Add more lemon batteries until the LED emits light.
5) Lets measure how much voltage in our circuit series.
6) Lets measure the voltage of each lemon battery.

The sum of the voltage levels of each battery should be equal to the voltage of the entire circuit series

Also note that the voltage will continue to increase until it reaches the LED, and will then move back to 0 to create the full circuit.

Great Job! We created our own battery!

STEM Education Standards

  • STEM Science StandardScience Standard
    Students will learn to test hypotheses through experimentation. Students will also learn about how batteries work and discover how to create their own battery.
  • STEM Technology StandardTechnology Standard
    Students will learn to use a voltage meter to measure how much voltage is found in each lemon or potato battery.
  • STEM Technology StandardEngineering Standard
    Students will be able to identify components, symbols and explain the function of a Battery, LEDs, and positive and negative charges.
  • STEM Technology StandardMath Standard
    Students will practice adding several voltages together. Students will also learn about positive and negative numbers on the voltage meter.