Battery Tester

The attached PDF can be used as a template to create a battery tester for AAA (or AA) batteries.

If you're like us you may have a whole bunch of AAA batteries around and not know which are new and which are used. This tester will solve that problem.

The Meter Power holds 3 AAA batteries to power the device, and the Test Battery holds a single AAA battery.

This project uses our 3D Printed Maker Tape Battery Holders but you can always make your own or use standard battery holders.

Throughout this guide we'll assume you're using the AAA battery holders, but if you prefer an AA version, make the needed adjustments along the way.

Start by cutting the paper switch from the side of the template.

The switch is the same one you'll find in our Switch - Lever Switch guide.

After you cut out the switch you'll need to add a fold (along the dotted line) and add Maker Tape that wraps around the switch.

You can add the tape to the switch now and set it aside, or finish it later after you've added the tape for the circuit paths.

Add Maker Tape as shown on the template.

You only need to add tape within the dotted border, don't add any to the switch on the right side!

Remember, Maker Tape can be overlapped and still work just fine since it's conductive on the top and bottom surface, and all the way through!

We placed our meter in the center of the circuit and taped it down as shown.

Place the wires on top of the tape paths as shown, and then tape them down.

The wires should be long enough to reach where they'll be secure down, but if not just add more Maker Tape to reach them.

The way the meter works is like this:

The red wire is positive power to the meter. Our switch will make sure it's only on when the switch is pressed.

The white wire is used to measure the voltage of our test battery.

The black wire is ground and needs to be connected to power the meter and to the test battery.

If you've done any of our Paper Crafts projects you're probably familiar with how we use a "Tape Loop" to hold down and connect a CR2032 Coin Cell battery...

We're using the same method here. Make four tape loops and add them as shown on the template.

If you haven't made your battery packs yet, make your Maker Tape Battery Holders before this step!

Add in your battery holders, making note of the polarity.

Finally, add the switch we made in Step 2.

Once you've got all the pieces in place you're ready to try your Battery Tester!

With everything in place all you need to do is press the Test Switch and read the meter.

If your battery is 1.50 or higher that's a fresh battery! 1.40 or lower? It's not dead yet, but it's pretty weak!