Science Models
Science Fair Projects

Published on May 25, 2017

Potato Battery


The objective: For my science project this year I chose to do potato batteries. My main objective was to see if my potato batteries could power a small buzzer or a high efficiency L.E.D. I tested my potato batteries in a series of different ways and had attempted many different circuitry designs. This gave me enough trials to come to a conclusion. I chose this topic because as science fair neared we started electricity in my class. After all the experiments and research I got really interested in the science of batteries and just electricity in general. I decided to learn more about electricity, so I looked into some projects related to the topic and thought this was the best and most interesting.


Batteries have 3 parts

1.An anode which is the negative terminal

2.A cathode which is the positive terminal

3.The electrolyte which is a compound that ionizes when dissolved in a solvent

The chemical reactions in a battery cause the electrons to build up at the anode. This results in a chemical difference between the anode and the cathode. This difference is an unstable buildup of the electrons. The electrons want to arrange themselves so that there is no longer a difference. But they have to do this in a specific way. The electrons repel each other and try to go to the place with the fewer electrons. In a battery the only place to go is a cathode. But, the electrolyte keeps the electrons from going straight from the anode to the cathode inside the battery. When the circuit is closed the electrons will be able to get to the cathode.

Potato Battery

In the picture above, the electrons go through the wire, lighting the light bulb along the way. However, these electrochemical processes change the chemicals in anode and cathode to make them stop supplying electrons. So there is a limited amount of power available in a battery (That’s when the battery runs out). Potatoes naturally contain salt, one of the most important ingredients for conducting electricity. In electricity, salt is important for conducting the current in the form of ions. When combined with water, the salt breaks apart into separate ions, conducting positive and negative charges to power a small electronic device


1.What makes a potato similar to an electrical battery?

The liquid electrolyte in a battery is similar to potato juice. Potato juice ionizes substances into their ions in a solvent just like electrolyte. That’s what makes a potato similar to an electrical battery, In order for it to give the potato power. In this same way, potato juice makes the electrons go in either the anode or the cathode. Then all the electrons travel through a wire from the anode to the cathode. Another similarity is that potato batteries and electrical batteries both have a limited amount of energy. When the flow of electrons in the battery stops, the energy runs out. Even though these two items have different acid levels on the ph scale they are both acidic enough to produce electricity.

2.What is a voltage and why is it important in a battery?

In a conductor, electrons can jump from one atom to another atom. Electrons need an electrical force to push them along. This force is called voltage. Voltage measures the amount of potential energy in a circuit. One end has more energy than the other. It is measured in volts, which, is the potential energy difference between two ends.
In a battery voltage measures how much potential energy is in the battery. Potential energy is closely related to voltage. In order to get potential energy in joules we need to multiply the voltage by a charge. In an electrical circuit, the charges that move around the circuit are called electrons.

3.What are the basic parts of a battery?

In a battery there are two ends. One is the positive terminal and the other is the negative terminal. The positive terminal is named the cathode. The negative terminal is named the anode. In the middle there is electrolyte. Electrolyte is a liquid that ionizes substances into their ions. A circuit connects the anode and the cathode in order to keep the flow of electrons going on.


•The open circuit voltage of a single potato series is 954 millivolts.

•The open circuit voltage of two potatoes series is 926 millivolts.

•The open circuit voltage for three potatoes series is 860 millivolts

•The closed circuit voltage of one potato series is 1 Volt

•The closed circuit voltage of two potato series is 0.6 Volts

•The closed circuit voltage of three potato series is 1.0 Volts

•You cannot measure the open circuit voltage of a potato with parallel

•The open circuit voltage of two potatoes parallel is 847 millivolts

•The open circuit voltage of three potatoes parallel is 824 millivolts

•You cannot measure the short circuit voltage of one potato with parallel

•The short circuit voltage of two potatoes is 0.7 volts

•The short circuit voltage of three potatoes is 0.9 volts

Potato Battery

Main question

Will the potato light the LED longer or power the buzzer longer?


I think that the buzzer will be powered on the potato batteries the longest. This is because it consumes the least amount of energy, 0.8 watts, compared to a LED which consumes 1.02 watts.


◦Veggie power kit which includes:

■3 copper electrodes

■3 zinc electrodes

■6 alligator clip leads

■1 digital multimeter with test leads

■3 Piezoelectric buzzer

◦super bright high-efficiency red LED

◦3 Fresh Potatoes





1.Create a table

1. You will use this table to record the open-circuit voltage and short-circuit current of your potato batteries and record whether or not they can power the light-emitting diode (LED) and the buzzer

2. Measure the open-circuit voltage and short-circuit current of a single potato battery.

3. Assemble your potato battery

4.Record whether or not a single potato battery can power the LED and the buzzer

5.Record and analyze your data


Will the potato light the LED longer or power the buzzer longer?

In conclusion the buzzer was lit up the longest because the LED didn’t light up at all. One thing that went wrong was that the LED didn’t light up. If my experiment went right the LED should’ve lit up. If I tried my experiment with 4 or 5 potatoes the LED would probably light up. I did some research as to why the LED didn’t light up and I found that the LED needs more energy to light up. My hypothesis was correct. The buzzer was powered the longest. But I was surprised to see that the LED didn’t light up at all. I thought that the led would light up but not as long as the buzzer, so in a way I was wrong. In real life I could use potatoes batteries for lighting up small little things like a remote control or a small clock. If I were to do this experiment differently I would use a few different items to test on. I would use an alarm clock, a flashlight and a TV remote control. Another thing I would do different is to try with 4 and 5 potatoes too.










Science Fair Project done By Ali Sunderji