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Battery Life Test

Which battery lasts longer?

Introduction: (Initial Observation)

Have you ever wondered what brand of batteries to purchase for your flashlight, toy or any other battery operated device?

Do you know which brand of battery will last longer?

If you like to know the answer, then testing and comparing batteries can be a good idea for your science project.

This is the type of work engineers and technicians do in a quality control laboratory. Both manufacturers and large buyers use quality control techniques to make sure they are producing or buying a high quality products that meet their expectations or requirements.

This project is also a good way to familiarize students with electricity and simple electric circuits.

Information Gathering:

Find out about batteries and how they produce electricity. Read books, magazines or ask professionals who might know in order to learn about the factors that may affect the life of a battery. Keep track of where you got your information from.

Following are samples of information you may find and report:

I researched on how a battery produces electricity. The battery is a dry cell. A chemical reaction between the electrolyte and the zinc electrode helps produce electricity.


  • Electrodes – The negative or positive part of an electric cell.
  • Electrolyte – A liquid or moist substance that conducts electricity.
  • Dry Cell – An electrical cell that has a moist electrolyte.
  • Terminal – The negative or positive end of a battery.

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

Question: Which battery brand lasts longer?

Purpose: The purpose of this project is to compare at least 3 different brands of battery and determine which one will last longer.

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

This is a sample of how you may define variables:

Independent variable is the brand of battery

Dependent variable is the life of battery (in hours and minutes)

Constants are the type and size of the battery and the light bulb.


Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.

This is a sample hypothesis:

I think the Duracell battery will last the longest. I also believe that the more expensive the battery the longer it will last.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”


I experimented by testing the power of four different brands of batteries. I did this by hooking up the batteries to a light bulb. I then kept track of the length of time each bulb stayed lit. I tested two batteries from each of the four brands.

How to assemble the circuit?

Make a simple electric circuit for each of the batteries you want to test. This is a sample instruction for preparing your electric circuit using an aluminum battery holder for D size batteries. This guideline will be slightly changed if use a plastic battery holder or if you want to test AA size batteries.

  1. Use two longer screws to mount the bulb socket on one end of your wooden plaque.
  2. Use short screws to mount the battery holder on the other side of your wooden plaque.
  3. Strip one inch of both ends of your insulated wires. Insert one end of each wire in one side of battery holder clips. Also connect the other side of wires to the screws of your bulb socket.
  4. Now you are ready to screw a bulb at the bulb socket and insert your battery for test.

Above pictures show how you insert and secure your wires in the battery holder clips.

Experiment Procedure:

Insert one test battery and screw the bulb until it turns on. Record the time and battery size and model. Inspect the bulb every 15 minutes until it completely turns off. Then record the time again and calculate how many hours and how many minutes did your battery last.

The bulb that you receive with your kit has a magnifier that helps you to see the filament.
Even at the last moments of your battery life, the filament may still be red. So wait until it loses all its light and redness.

If for some hours you are not able to inspect the light, turn it off. Turn it back on when you are ready to inspect it again every 15 minutes. Keep track of the hours that you turned the light off and deduct it from final hours that you calculate. to turn off the light, you may loosen the bulb by turning it counter clock wise or by removing the battery.

The battery holder you use must match the size of battery you are testing.

Record the results in a table like this:

Battery Life
Trial 1
Battery Life
Trial 1
Battery Life
Trial 1
 Battery Life
 Battery 1  
 xxx minutes
 Battery 2
 Battery 3

How many circuits do I need for my experiments?

You will need one circuit for each battery you are testing. In this way you start all tests at the same time and you are sure that all tests are performed in the same environmental conditions (temperature, light, humidity). If for some reason you are not able to have multiple circuits, you may test the batteries one at a time. This method is not reliable and there will be more chance for errors.

Either way you must test each brand battery at least 3 times and then take average of your results.

How long does it take?

Batteries take a long time to discharge. Make sure you have enough time for your experiments and repeating them.

Materials and Equipment:

You may buy the necessary materials for your experiment in the form of a kit or you may try to buy them separately. Either way you must make a list of materials you use and include that in your report.

This is a sample list of materials:

Paper, wires, stop watch, battery holders, bulb holder, computer, light bulbs, and graph paper. Batteries (Duracell, Everready, Energizer, …)

Is everything included in a kit?

Different kits available for this project usually include the battery holders, bulb holders, light bulbs and connecting wires for 1 to 4 batteries. While selecting a kit, pay attention to the size of batteries you may test and the number of batteries you may test at the same time. Kits do not include batteries, screw drivers and other materials you may need for your display and report.

This is a sample content of a kit used to assemble a basic electric circuits to test general purpose alkaline D cell batteries:

1 Mounting Board
1 Miniature Base or socket (bulb holder)
1 Miniature Light Bulb
1 Battery Holder (for D size)
4 Screws
some insulated wire

Basic Kit

This picture shows a circuit assembled from the BASIC battery life test kit of MiniScience.com.

As you see you can use it to test only one large (D size) battery. So you will need more than one of this if you need to test multiple batteries at the same time.

Standard Kit

This picture shows a circuit assembled using the Standard battery life test kit of MiniScience.com.

As you see you can use it to test up to 4 small (AA size) batteries at the same time.

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

Sample Results

After the testing was completed the following results were recorded: The Duracell battery lasted the longest, 101 hours and 20 minutes; Energizer battery, second, 99 hours and 17 minutes; Eveready battery, third, 28 hours and 30 minutes.

The problem with this sample result is that it does not specify what size batteries have been tested. Make sure you write the size of batteries (AA, C, D) in your results.


You will need to test each brand 3 times and then calculate the average of their lives (in hours and minutes).

Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.


Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

This is a sample:

I thought the Duracell battery would last the longest. I guessed right! It was two hours and 3 minutes longer than the Energizer. I also determined that the cost of the battery does relate to the amount of battery power.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Question: How can I use the D size battery holder for C batteries or AA batteries?

Answer: With some padding and any conductive spacer you can fit a smaller battery in a D size battery holder.

Padding can be made of paper towels, cardboard or Styrofoam boards. Padding will raise the battery so the battery poles are aligned with the contacts of the battery holder.

Spacer is any conductive object that can extend the battery length enough to touch the contacts of the battery holder. Spacer may be a short screw or a few coins. In either case you must be careful and make sure that the spacer is only touching the contact of battery holder, not its frame.

P.S.: It would be much better if you would order/ purchase the right size battery holder for your batteries.

What did I learn from my experiment?

I learned that science fair projects are a lot of hard work. The most powerful battery of the four I tested was Duracell. It also was the most expensive.

How close were my hypothesis and conclusion?

I guessed that Duracell would last the longest and I was right. It was also the most expensive.

Did I learn anything new from my project?

Yes I learned through this experiment that if you buy a more expensive battery you get a more powerful battery.

What was the most interesting part of my project?

It was when my hypothesis and conclusion matched.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.


List your references in this part of your report.