Science Buddies: "Ask an Expert"

I am writing to you with a couple questions about the Battery that Makes Cents Project


I am a sophomore at Brewster NY High School and I plan on completing this for my chemistry class

Couple questions:

1) How long should I expect the battery to maintain it's charge? For Example if I complete it at home one night can I expect that it will hold it's charge long enough to demonstrate in class about 8 hours later or do you think it best to just complete it live in class?

2) Do you think it would be possible to get this homemade battery to get enough of a charge to light a light bulb (maybe 25 or 40 watt bulb) , if so approximately how many coins do you think I will need.

Thank You

Hi jayman0320,

Testing the time that the battery can produce current would make an interesting “extra” experiment. To find out how long this kind of battery lasts, you could make up a fresh battery, connect to your multimeter, and take readings every 30 minutes until the battery no longer produces current.

The paper towel layers in your coin battery need to be moist for the electrolyte to carry the current. So I suspect that the amount of time that the battery will supply current depends on how long it takes for the paper towel layers to dry out. My suggestion it to make up the battery just before your demonstration in class.

I don’t think your coin battery will produce enough voltage and current to light a 25 or 40 watt light bulb. But you should be able to light a low voltage LED. You’d need about 1.4 volts from your battery to light this kind of LED. If you have 5 or 6 nickel/penny cells stacked together you should have enough voltage.

I hope this helps. Please post again if you have more questions.

A. Norman