Introduction: (Initial Observation)

A 2,200-year-old clay jar found near Baghdad, Iraq, has been described as the oldest known electric battery in existence. However, most historians date the invention of batteries to about 1800 when experiments by Alessandro Volta resulted in the generation of electrical current from chemical reactions between dissimilar metals.

You are watching: Which battery lasts the longest science fair project


Today batteries are used in millions of portable electronic equipment such as watches, cameras, calculators, radios, cellular phones, flashlights, computers, remote controls and many other equipment.

Why do we use a battery?

The portability of batteries, as a source of electricity, makes it the favorite choice for mobile applications. The fact that batteries can be very small makes them the only choice for small electronic devices. Billions of batteries are being sold around the world every day.

Since we are so dependent on batteries for our electronic devices, it is important to know how long each battery will last and how we can increase the power.

Advertisements on T.V. often suggest certain brand batteries last longer than others. Now I have to find out for myself. I also need to know if there is a real difference between battery lives of different brands, and what the reasons for this may be.


This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “Ask Question” button on the top of this page to send me a message.

If you are new in doing science project, click on “How to Start” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.

Project advisor

Information Gathering:

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

During your research you may use books, Internet, Encyclopedias or professionals whom you might know.

I started my research by finding out how many different batteries exist in the market. Hardware stores, electronic stores and even many general stores and supermarkets sell batteries. Looking at the brand names, I saw Duracell, Energizer, EVEREADY, Panasonic, Sanyo, Kodak, and hundreds of other brands. While checking the brands, I noticed that batteries are made in large varieties of shapes and sizes for different applications. For example, there are many specialized batteries for cameras, watches, notebook computers, lanterns, hearing aid devices, automobiles and many more. I also noticed that some are much more expensive than others. By comparing the labels and asking some questions, I learned that expensive batteries are normally the rechargeable ones. Rechargeable batteries contain expensive chemicals such as silver, Nickel and Cadmium compounds, which makes them more expensive than normal batteries.To narrow my research and prevent more confusion, I decided to concentrate only on general purpose batteries that are also known as flashlight batteries. These batteries are made in different sizes, but the three most common sizes are:


These batteries are used in many household electronic devices such as calculators, portable radios, some telephones, clocks and of course, flashlights. Unlike rechargeable batteries, these are called Alkaline Batteries. I would like to find out what the chemicals in these batteries are and why they are called Alkaline.All these batteries, except the one that is called 9V, produce 1.5 Volts electricity. As a matter of fact, the one that is called 9V and produces 9 volts, is actually a package of 6 smaller 1.5 volt batteries attached together to produce 9 Volts.AAA size is too small and slightly overpriced. So I eliminate 9V and AAA from my research and stay with AA, C and D size alkaline batteries.

Additional information are available below:

Learn about different batteries

Alkaline Batteries

Samples of battery related projects:

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.

After some research I narrowed down the subject of my project to this:

Among famous brand batteries (such as Duracell, Energizer, EVEREADY, Panasonic and Sanyo) in AA, C and D sizes, which one last longest?

The purpose of this project is to find out “Which of the popular brand batteries lasts longest?”.

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.

The independent variable (also known as manipulated variable) is the battery brand. (Possible values are: Duracell, Energizer, EVEREADY, Panasonic, Sanyo).

Dependent variable is the battery life time (in minutes, hours or days)

Controlled variables are the environment temperature. (We perform all of our tests at the same time and at room temperature of about 72 degrees Fahrenheit.)

Constants are the experiment procedures, method and instruments including the load. Load is something that will consume electricity such as a light bulb. Some light bulbs will consume more electricity, creating more light and more heat. It is obvious that such loads will discharge the battery much faster. Selecting the load as a constant means that all batteries will be tested with the same type and size of light bulb.

We also record a third dependent variable that is price. In this way we will find out if the price has any relation with battery life!


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.

My hypothesis is not based on scientific information, Instead it is based on market information. Battery has a competitive market and many manufacturers are competing with each other to get a larger share of this market. Price is an important factor and if one brand has a higher price, this probably means a higher manufacturing cost that can lead us to a better quality product (in many cases). So I think the one that is more expensive will last longer.

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.”

Experiment 1:

Comparing battery life using light bulbs.

Introduction: A battery that has a longer life can keep a light bulb on for a longer time. We can use this property as a test method to compare the life of different batteries. The following procedure is for comparing different battery sizes and different battery brands. If you are planning to compare only different brands or only different sizes, use the experiments 2 or 3.


For each size battery (AA, C and D), build a simple electric circuit, including a battery holder, a lamp holder and a light bulb. Use these circuits to test how many hours a light bulb will stay on with each battery and record the results in your results table.


If you are testing large batteries with small light bulbs, they may take more than 24 hours to discharge. You must be able to observe the final hours and the final minutes of your experiment. For this purpose you may interrupt your experiment at nights and other hours you are not able to watch the lights. If you do so, you must make a note of the start time and the end time of each test period. You will later use these notes to calculate the total number of hours each battery produced light.


Instead of constructing simple electric circuits, you could use identical flashlights.

Experiment 2:

Comparing the life of different battery sizes.

A battery that has a longer life, can keep a light bulb on for a longer time. We can use this property as a test method to compare the life of different batteries. The following procedure is for comparing different battery sizes of the same brands.


For each size battery (AA, C and D), build a simple electric circuit, including a battery holder, a lamp holder and a light bulb. Use these circuits to test how many hours a light bulb will stay on with each size battery and record the results on the following table.

Battery size Battery life/hours

Experiment 3:

Comparing the life of different battery brands.

A battery that has a longer life, can keep a light bulb on for a longer time. You can use this property as a test method to compare the life of different batteries. The following procedure is for comparing different battery brands of the same size.


For each brand battery (Duracell, Energizer, EVEREADY,…), build a simple electric circuit, including a battery holder, a lamp holder and a light bulb. Use these circuits to test how many hours a light bulb will stay on with each size battery and record the results on the following table.

Battery BrandBattery life in hours

You could use identical flashlights for this project. Note that all batteries that you test are the same size, the only independent (manipulated) variable is the battery brand. All circuits or all flashlights must have identical light bulbs.

What is the control for this experiment?

A control is another battery that you do nothing with that. You just test it before and after your other experiments. Control will show that the batteries did not lose their energy by accident or by unknown factors.

How long does it take?

This experiment may take as little as a few hours up to a few days for each battery depending on the battery size. AA size batteries usually need less time. D size batteries take the most time.

A New Method:

In the previous method you had to visually detect the loss of power in the battery by looking at the light bulb filament. In this new method, you use the battery to build an electromagnet. The electromagnet will be strong enough to hold a nail or a paper clip. When the battery weaken, the nail or paper clip will fall. In this way you can be doing your other works and record the time when you hear the sound of a dropping nail or paper clip.

You will need two wood dowels and a base board for this experiment. Mount one wood dowel vertically on the base board and mount the second one horizontally at the top of the first one. Use wood glue (Elmer Glue) to bind them together. Give them a few hours to dry. Insert a nail in one end of the upper wood dowel. Wrap some wires around the nail (about 200 turns) and connect the ends of wire to the battery holder.

Place the battery in the battery holder and hang another nail or any other metal object to your electromagnet. Record the time and wait until the metal object falls. Record the fall time again.

Remove the battery and leave it out for one hour and then repeat the test again. This time the metal object falls in a shorter time.

Subtract the start time from drop time to calculate the battery life in your first and second experiment.

Record the results in a table like this:

Battery LifeExperiment 1 Battery LifeExperiment 2
 Battery 1 xxx minutes
 Battery 2
 Battery 3

Note: If the nail that you use for the core of electromagnet is not soft, it may become a permanent magnet. In this case a small weight such as a paperclip may never fall down. Make sure you use the heaviest metal piece that your electromagnet can hold.

Although most electromagnet diagrams show only a few turns of wire around the nail, in making an efficient electromagnet, you must use much more loops of wire to avoid overheat and get a strong electromagnet.

The main purpose of diagrams are to show the way you wrap the wire around the iron core.

A single strand of wire must be wrapped in one direction only. Wires can overlap as many times as needed.


The following experiments are recommended for senior high school and junior college students.

Experiment 4:

Measure the energy of each battery

This is a sample experiment for higher grades who need to measure the total energy of each battery in calories, joules or watt hours. I am suggesting 3 different methods to choose from. Younger students are most likely unable to understand and follow these procedures.

Introduction: When a battery lasts longer, it does not necessarily mean that the battery is better or stronger. A battery may last longer simply because of a slower discharge or slower rate of producing electrical energy. Measuring the total energy of a battery is a good way of evaluating batteries regardless of the production or discharge rate.

Method 1:

In this method, you use a battery to produce heat and then measure the amount of heat energy. For example each calorie energy can increase the temperature of 1 mL water by 1ºC. This is the method that we describe in this experiment.



Make a small Styrofoam box about 5 cm x 5 cmUse an aluminum foil to form a cup over a small 2.5 volt light bulb.Connect the light bulb to the battery via a switch.Place the light bulb and the cup inside the foam box.Use a pipette or graduated cylinder to fill up the cup with 15 mL water (or any known amount).Add a drop of mineral oil or olive oil to the water to prevent surface evaporation.Insert a thermometer through the box lid and into the water. Now the box lid must be closed tight.Wait about 1 minute and then record the temperature of water.Turn on the light. Record the temperature of water every hour until it starts to decline.Multiply the amount of water (in mL) by the temperature change (in Celsius degrees) to calculate the battery energy in calories. You can multiply your results by 4.184 to convert calories to Joules.

Method 2:

In this method, you use a battery and a small electromotor to lift an object and calculate the used energy in Joules. If your electric motor needs 2 batteries, you may use 2 identical batteries and then divide your calculated energy by 2.


Get a battery operated electric motor with an extended axle of about 2 inches. (You may need to attach another rod to the motor to extend the existing axle.)Connect a string to the axle and connect a weight to the other end of the string.Turn on the motor. The axle spins and pulls the string like a spool. Weight moves up until it gets to the axle. Stop the motor before the weight gets to the axle. (depending on your motor, it might be able to lift up to a few grams).Record the weight (in Newton) and the distance it moved up (in meters). Note that 100 grams is one Newton.Repeat this until the motor does not work any more. You may need to use smaller weights as the battery weakens.Record your results in a table like this. Calculate the energy for each row by multiplying the weight by the distance.
TrialsMass lifted (Newton)Distance lifted (Meters)Energy in Joules (Newton Meters)
 Total energy of battery is the sum of calculated energy in all trials:

Method 3:In this method, you calculate the amount of energy by measuring the voltage, current and time while the battery is being discharged by a light bulb.


Measure and record the resistance of your light bulb (in Ohms). You will later need this to calculate the current in your circuit. To do this, you simply connect the wire leads of an Ohm meter to the connections on the bottom and on the side of the light bulb screw base.

2. Connect your light bulb to a battery. At the same time connect a volt meter to the battery. Record the voltage and the time.

3. After one hour, record the voltage again. Continue recording the voltage every hour until the voltage becomes very low (or less than 0.2 volts).

4. Calculate the average voltage of every hour of operation. To do that add the beginning voltage of each hour with the ending voltage of that hour and then divide it by two.

5. Record your results in a table like this:

HourAverage voltage(Volts)Average Current(Amperes)Rate of Energy Production or consumption in Watts.
1 (first hour)

The formula that defines the relation between resistance, voltage and current is

V = I . R or I = V / R

Divide the voltage by the resistance of the light bulb to calculate the current in amperes. Write that in your results table.

The formula to calculate the hourly rate of energy is

W = V. I

Multiply the average voltage by the average current to calculate the rate of energy production in Watts. Write them in your results table.

The sum of watts in all hours that your battery was being discharged is the total energy in watt/hours. Multiply that by 3600 to have the energy in Joules.

Some notes:

A strong AA type battery yields about 1.4 watts for one hour.1 Wh = 3600 J1 calorie = 4.184 joule

Additional activities:

Develop a game

A battery, a switch and a light bulb together form a simple electric circuit. You may use one or more simple electric circuits to develop different games. In most of these games turning on a light will reveal the correct answer to a question or will reveal a part of the question. For example you may develop a simplified version of GEOPARDY or some educational games.

Hear is a simple idea that you may call it Science Challenge Game:

Show a card with a question and four answers to a friend. Your friend will guess the answer and conform the answer by turning on a switch. If the answer is correct, the word RIGHT will light up; otherwise, the word WRONG will light up.

Make an electric circuit on a wooden board or cardboard with 4 switches, four light bulbs and one D size battery. Use solid insulated copper wire gauge 22 for connections.

To make your device more interesting you may run the wires from behind. Make small holes so the wires can go behind and bring them up to the surface through another hole next to the connection screw where it must be connected.

This will be the base for your game device.

Now you need to make a 3 layer mask for each of the questions. 

Cut a black cardboard to mask the lights and have only four square openings for the lights to come out.

Put a white paper over the black mask and write 3 “WRONG”s and one “RIGHT” over the squares.

Put another white paper above this with 4 numbers. At this time the words wrong and right are not visible unless you turn on the light.On the empty space of this card write the question and four possible answers numbered 1 to 4.

Make sure that your right answer is aligned with the word “RIGHT” or has the same number as the word “RIGHT”.

You will need to make one three layer card for each of the questions in your game.

Image in the right shows how the word wrong will become visible when you close the switch number 3.

Size of the cards, method of cutting and connecting the three layers are optional and you have many different options. Try this activity only if you have access to the skills and materials you may need. Project advisors do not provide any support with this activity.

Experiment 5:

Increase battery life by heat

Introduction: It is known that heat can help and increase the rate of chemical reactions. Since a chemical reaction inside batteries is the main drive of electric current, we may be able to use heat to increase this reaction.


After your batteries are fully discharged, drop them in a pot of hot water for 1 minute. Then try them again as you did in your experiment 1.

Did heat gave a new life to your dead batteries?

Materials and Equipment:

Material used for this project are:1. Mounting Board2. Miniature Base3. Miniature Light Bulb4. Battery Holder5. Some wires and screws

Available at Electronic Stores, Hardware Stores and online store of

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.

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.

By analyzing your findings, you may now answer the second part of your question as well.

The second part of the question is: “How can power be increased?”

Since all the batteries you have tested are the same type and the same size, the only difference affecting the battery life can be the quality and the composition of chemicals in each battery. So in your conclusion you may also suggest that the battery life can be increased by fine tuning the chemical composition. Of course this is what manufacturers must do.

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.

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.



I tested 6 different AA batteries using a small light bulb. I did four battery trials using batteries from the same bubble-wrapped package. I used new light bulbs for each trial and obviously fresh batteries.

The same kind of batteries (Energizer, Duracell, Interstate, Sanyo, CVS, and Radio Shack) acted differently for each trial. Some times they ran significantly longer or shorter than the other runs of their same kind. Why?

Sometimes the battery spiked at an hourly measurement. Instead of going down like expected, it went up for one hour but then continued down on its usual course, why?

Why were the six batteries so variable? They were all about the same price (except for the CVS) and all had the same “use by” date. What made some last so much longer than the others?


Different brands of batteries have different composition of chemicals that can affect the battery life and the rate of discharge.

When comparing the batteries, it is best you compare them at the same time and in the same room. In this way you will be sure that batteries are under the same environmental conditions. Temperature changes will change the rate of chemical reactions in the batteries and cause different rates of producing electricity. For example in cold temperatures batteries seem to be weaker, but they will last longer.

See more: How Does Pressure Affect The Solubility Of A Gas, Solubility And Pressure



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