Converting from CR2032 to AA batteries

Coin or button batteries are expensive and most people don’t have extras laying around. So when practical why not convert your device to AA batteries instead? Like recently my indoor thermometer needed a new CR2032 battery. Instead, I converted it to use AA batteries.

CR2032 converted to AA batteries.

This is a super simple switch that I wanted to share because I’m not sure most people even think about it. The CR2032 and other CR batteries are 3 volts. 1 AA battery is 1.5 volts. So 2 AA batteries equals 3 volts.

That works out perfect and 2 AA batteries will last a lot longer than one little CR2032. Plus you can also use rechargeable ones if you wanted to.

Battery Slot
CR2032 Battery slot.

The first thing I did was open up the thermometer to see what I had to work with. I found a nice slot for sliding a battery in and out. This seemed perfect. I thought that I could put wires on each side of the old battery and slide it back in. But I didn’t want to worry about how the battery would react to the incoming current from the wires. So I decided I’d make some kind of spacer instead.

My first idea for the spacer was to cut out a coin shape of cardboard from a box and tape wires to each end of it. But then I remembered I had a 3D printer so I took some measurements and printed out a plastic CR2032.

It turns out the number on the button battery is the size of the battery. 20mm by 3.2mm. I learned something new. 🙂

Getting the measurements.

If you want the 3D printer file for yourself then you can download it here.

CR2032 3D Model
CR2032 3D Model

Once it was printed I just taped some wire to each side making sure the stripped copper would touch the insides of the battery slot. In this case, I used wires that came from the inside of a network cable.

Plastic CR2032 wired up.

It fit nicely.

Testing the fit.
Testing the fit.

Now I made a hole in the side of the case so the wire could come out.

Wire hole.

Now I put it back together. I think it looks nice.

Case with the wire hole.

With that done we can move on to the AA batteries. I had this nice case laying around so I decided to use it.

Battery case.

Now to wire it all up with a breadboard.

Everything wired up.
Everything wired up.

Your device is now converted from CR2032 to AA batteries

Once you know it works you can do something more permanent. I’m going to keep mine on the breadboard for now because I’ve got another idea to convert this to solar-powered later on.

I hope you enjoyed my little project and I hope that it will give you some ideas and save you some money in the future.

Leave a comment and let me know what you think and I’ll cya in the next post. Until then take care!

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