Introduction  To compare the power of different brand of batteries we can use them to light-up identical light bulbs and record the time each battery can kip the light bulb lit. For best results, all batteries must be tested at the same time so that they will all be under the same environmental conditions. So if you want to compare 4 different batteries, you must have 4 identical electric circuits. Materials or kits for this project For each of the batteries you want to test you must have a simple electric circuit with a battery holder, a light bulb with mounting base and connecting wires. You may optionally mount everything on a wooden board. Make sure the battery holders are the right size for the batteries you are testing.

Materials included in the Basic Battery Life Test kit include:
1 Mounting Board
1 Miniature Base or socket
1 Miniature Light Bulb (2.2 Volts with Lens, or 5.1 Volts without lens)
1 Battery Holder (for D size)
4 Screws
some insulated wire

Materials included in the Standard Battery Life Test kit include:
1 Mounting Board
4 Miniature Base or socket
10 Miniature Light Bulbs (2.2 Volts with Lens)
4 Battery Holder (for AA size)
12 or 16 Screws
Connection wires are already attached

 How to assemble the basic kit?

Use two longer screws to mount the bulb socket on one end of your wooden plaque. Use short screws to mount the battery holder on the other side of your wooden plaque. 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.

How to assemble the standard kit?

Attach the red wire and black wire of each plastic battery holder to the contact screws of a lamp holder. To do this first loosen the screw, push the bare portion of the wire under the screw or under the plate and then tighten the screw. You may need to hold the nuts at the bottom side of the lamp holder while tightening the screws.

2. Now that each battery holder is connected to one lamp holder, you can start mounting the battery holders and the lamp holders on a wooden base. Each lamp holder will need two screws and each battery holder will need one or two screws.
    
3. Insert the batteries. You have 4 battery holders so you can test up to 4 different brands.
    
4. Now you are ready to screw the light bulbs and record the number of hours each bulb will stay on.

How to do the tests with basic kit?

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 that you receive with your kit is designed for the D size battery. To test other sizes, that are smaller, you will need to put something in battery holder to raise its bottom and since other batteries are shorter, you will need to use a piece of metal such as a spring or screw as a filler to attach the battery ends to the connectors of battery holder.

How to do the tests with standard kit?

1. Fill the battery holders with 4 different brand batteries.
2. Screw the light bulbs in lamp holders so that they all lit.
3. Make observations every 15 minutes and record the time each battery looses its power.
4. At any time you are not able to continue your observations, loosen all light bulbs so they will turn off and stop consuming electricity.

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 dropping nail or paper clip.

Two wood dowels are included in your kit. 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. (Your wood dowel may already have a hole for this). Wrap some wires around the nail 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 Life Experiment 1	Battery Life Experiment 2	Price
Battery 1, Energizer	13 hours		$0.87
Battery 2, Rayovac	13.5 hours		$0.75
Battery 3, Ever Ready	10.5 hours		$0.50
Battery 4, Sony	8.25 hours		$0.25

Values shown in the above table are only sample values selected randomly. They may or may not be correct. Students must perform their own experiments and report their own results.

Answer: The strength of magnet depends on the number of turns of wire on the nail. More wire results more magnetism. Less wire results more heat. (If you don't remove the insulation from the two ends of wire, you will get neither magnet nor heat. You can order additional light bulbs online or by calling (973)777-3113.

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.

If you don't already have the materials for this project, you can order them online.

Select the kit you need for your project
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.
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.

This kit is also for a simple electric circuit you will use in this project.

A completer project guide for this project is available at ScienceProject.com.