A Battery

A battery fit for the job

Batteries are a very handy source of power. Just think of all the things that use them - calculators, cassette players, even computers will run on batteries.
You'll know that there are different kinds of batteries, and maybe that some are good for some jobs, and some for others. But battery power is expensive. It would be really good to know which batteries are best for certain jobs.
For a first experiment, I wanted to see if batteries were different, so I tested two to destruction - I left them to power two lamps until they were used up.

What I did

I set up the two circuits as shown below. You'll see that I used a light sensor to measure the brightness of the lamps.

batter2.gif (6597 bytes)

The results

This is the graph show the life, and death, of the two batteries.

battery.gif (4614 bytes)

You will find some of the following questions easier if you put these results into your data logging software.Get the battery SID file, then Open the file in your data logging or spreadsheet program. If you want know what a SID file is read the Using SID page.

Looking at the results

	I can't remember which battery is which. Have you any ideas?
	They say that alkaline batteries work for longer and then fade away quickly. Zinc batteries work for less time and fade away steadily. Does this help your choice?
	How long did each battery take till it was exhausted?
	The alkaline battery cost three times as much as the zinc battery. Use the information you have to calculate which battery offers the better deal.
	Does this experiment tell you anything to help your choice of battery for a torch?
	It seems that one of the batteries isn't very good. Do you have any questions about how reliable these results are?

What you might try to find out

Single cells come in several different sizes - A cells, AA cells, AAA cells. Do you get more battery power in a larger battery?
In my experiment I used light sensors but you might instead have used voltage sensors. These measure the potential difference across the battery which should drop as the battery is used up. Do you think this is better?
Can you think of a way to test which type of battery is best for a torch, and which is better for a portable cassette player.

Where to get help

For other ideas and clues about what you need, see the Battery logging experiment.

This page was contributed to Schools Online for your use in school by Roger Frost, IT in Science.
Idea and results file by Laurence Rogers, University of Leicester.