Energy and Science Projects
For Students

Battery Life -- A Science Experiment
(Based on an Experiment Submitted To Us By Tracy and Emily)

Problem Statement

The problem is: Which battery lasts the longest out of four different brands, Duracell, Energizer, Eveready and Rayovac?


We think that Duracell will last the longest because their advertising claims that no other battery "beats the copper top."


  1. Four of the same type, size and brand flashlights.
  2. Two D-size batteries from each of the following brands:
  3. Two other D-size batteries to test each flashlight and bulb before starting tests.


We tested each of the flashlights by using the two test batteries. We then labelled each flashlight with the battery brand name and put the different batteries in each marked flashlight.

Before going to bed we will turn on all the flashlights at the same time and left them on overnight. We'll note down the time that the flashlights were turned on. When we wake up we will watch the flashlights until they go out and will record the time. If one goes out before we wake up, we will get two more of the same type of battery and watch it during the day.


Our variable is the different brand of batteries. The controlled condition is the same type of flashlights.


Our experiment showed that Rayovac outlasted all of the other batteries we tested by at more than two hours. The Eveready battery, which is a regular, non-alkaline battery, lasted only 6 hours and 35 minutes. The Duracell lasted 15 hours. The Energizer lasted 22 hours and 15 minutes. The Rayovac lasted 24-1/2 hours.

Life of Batteries

[Graph of Life of Batteries]

The Eveready flashlight went out during the night, so we had to replace the batteries and watch it during the daytime. It was the only non-alkaline battery. We observed that when it was going dead, it got very dim. The alkaline batteries just went out completely.

Brand Duracell Energizer Eveready #2 Rayovac
Turned on 9:00 p.m. Fri 9:00 p.m. Fri 10:00 a.m. Sat 9:00 p.m. Fri
Burnt out 12:00 p.m. Sat 7:15 p.m. Sat 4:35 p.m. Sat 9:30 p.m. Sat
Total Time
Turned On
15 hours 22 hours
15 minutes
6 hours
35 minutes
24 hours
30 minutes


We rejected our hypothesis that Duracell would last the longest. We came to this conclusion because our data show that Rayovac lasted longer than Duracell. This also proves that even though batteries may be more expensive (like the Duracell was), you might not be paying for a better battery.

We do suggest that further testing be done, due to a few errors made during the experiment. Some flashlights were accidentally dropped, which could have caused differences in the results. The expiration dates of the batteries were not all the same (there was a difference of a few months); so some batteries may not have been as "fresh" as the newer ones.

This Energy Education Project comes from the California Energy Commission
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