[Brigette Richter]

Brigette Richter asked the Naked Scientists:
   
Dear Dr. Smith,

I saw your webpage about freezing a battery and comparing the results with a battery stored at room temperature.  The article shows the chemistry of standard batteries, which I was interested in finding out about.  

I am a 6th grade student at St. Leo the Great Catholic School in Fairfax, Virginia, USA.  I am making an experiment for my school's consumer convention regarding how long consumer batteries last when compared with one another.  I plan on buying batteries from the 4 main manufacturers in the USA and comparing their length of life to one another.  I plan on using standard "C" cell batteries.  This I will test by placing them in identical flashlights and measuring how long each type of battery lasts.  I hope to be able to find out which batteries last the longest so people can buy the better battery.  

What things can make the experiment go wrong or make the comparison difficult because some batteries might last much longer than others?    

I thank you for your attention to this question.  

Sincerely,

Brigitte Richter

What do you think?

[Geezer]

Hi Brigette,

Should be a good experiment.

There are probably lots of things to be concerned about. Here are a few I can think of.

You probably need to test several batteries from each manufacturer to make sure the results are consistent and that you didn't just get a bad sample.

The light bulbs may not all draw the same amount of power, so it might be better to use calibrated resistors instead, or, always use the same bulb for all the tests.

It might be good to measure the voltage and current from each battery and plot the values onto a graph against time if you know how to do that.

You might go with smaller batteries (AA or AAA). That might speed up the experiment quite a bit.

The room temperature should ideally be the same for each run of the experiment, but you seem to have a handle on that.

Perhaps others will add some more suggestions.

Good Luck!