Homemade Batteries

Grade Level: 
Middle School
Subject: 
Alternative Energy, STEM

Lesson plan developed by Keith DeWeese

Overview: Students will make batteries out of lemons, potatoes and themselves and hook them up in a variety of ways.

Purpose (Objective): Students will discover how a battery works, as well as learn how current and voltage relate and interact.

Materials: Potatoes, Lemons, Galvanized (molten, not electrogalvanized) nails, 3” copper wire sections, 2 wires with alligator clips on the ends, Sandpaper, Multimeter

Background Information: Explain how voltage and current relate using the equation V=IR. You can go into great detail about the units used as well (ohms, amperes, volts).

Explain how series voltages add together while parallel ones don’t. Now explain how parallel currents can add together.

 

Activity:

1. Sandpaper the copper wires. This isn’t always necessary, but junk can build up on them.

2. Stick the nail and the wire into the potato or lemon. Don’t allow them to touch on the inside.

3. Take the wires with alligator clips and connect one to the nail and one to the copper wire. Measure the voltage with the voltmeter. Measure the current.

4. Take the whole class’s batteries and hook them up in series and parallel and prove that series voltages add together while parallel currents increase one another. Repeat the entire activity letting each student hold the wire in one hand and the nail in the other.

 

Safety Tips: The wires and nails can be sharp. Also, lemon juice in the eye hurts! Don’t worry — nobody can get shocked in this experiment.

 

Concept Discovery: Show the kids that if a whole class links together they can generate 15-20 volts. Give examples of what kinds of voltages are used (12 for a car, 120 for house, 1.5 for a battery). Use their fear of getting shocked to explain current and why you have to have current to get shocked.

 

Elaboration: Talk about large quantities of electricity — transformers and other things. Put the electricity they are making into perspective.

 

Closure: Review the concepts again next week. See if they remember current and voltage and the differences between parallel and series circuits.

 

Assessment: Ask students to write something they learned on an index card to turn in as an "exit card."

 

Integration with Other Content Areas: This was a good activity to explain prefixes, such as milli. 

 

source: http://www.engr.ncsu.edu/theengineeringplace/educators/lessons/battery.php