Digital Caliper Battery Mod

Upgrade our Dollar Store digital Caliper with a new Battery Case.

creator: x14km2d | build: 2021-12-18 | update: 2021-12-30


There are people who say that they have no idea what to build or modify. That is simply a lie. If you look around you will find hundreds of thousands of problems that you can solve. Maybe you’ll find that your Gameboy Color should have a rechargeable battery
installed, or maybe you can repair something. If you are creative and open minded the problems will come by themselves and that’s totally great, because then you have something to do and don’t think too much about our broken world. We still have to fix that too, but everything in its own time. We start small at first.

I work daily with a digital caliper that I bought at a dollar store. This is not a special tool. Almost all plastic and cheaply made. But it is one of my favorite tools. I also had a professional caliper made of metal with an analog display but somehow I switched back to the cheap caliper. No idea why, because actually professionals find these rather bad to work. That’s good, because I’m not a professional so I may work with tools what I like best. Unfortunately, the battery is always quickly empty, because this is a small (and extremely expensive) button cell1. I would have to replace this times, but how?

By chance I found here this Nitter2 thread in which a person describes exactly the
same problem and also shows a modification. Ben shows but only a few photos and that was it. But if you are just new to electronics the project can be a bit big. So I rebuilt it here and will explain all the steps in detail. But you should have already worked with a soldering iron, hot glue gun or 3D printer.


Material we do not need much. I downloaded the model for the new battery box and printed it in my 3D printer. I bought a new battery3 at the Dollar Store4 in a 12 pcs. Pack and that should last me the next few years. Then some old cables and a bit of copper tape.


In the first step we need to separate the LED from the two cables. this is best done with an old pair of scissors or a small side cutter. After that we need to strip the two ends of the cables with wire strippers. You can also do this with nail scissors, but please don’t do it with your teeth. Teeth break faster than pliers and are also more difficult to repair.

Now we stick the copper tape5 to the two ends of the battery compartment. The two poles (minus and plus) of the battery are then connected to these. So it is important that the copper tape touches the metal of the battery. On the side where the data is printed, the battery is not conductive. Finally, I mark on which side is the plus or minus pole. In the battery compartment you can also see how the battery is to be inserted. I make myself a red and black dot at the right place so that I do not forget when tinkering.

Since the soldering iron has to warm up for a few minutes, I prepare it now. I connect it to the power supply and put it aside. In the meantime I can continue working. If you have projects with many small tasks to be done, it is important to sort them out beforehand. Then you can work better and make fewer mistakes. At the beginning it’s a bit difficult, but with time it gets easier and easier because you gain experience with each project. Like in a computer game, where you collect EP (Experience Points) to learn new skills. Almost like real life.

Here you can see the side of the digital caliper where our modification will be attached. Again a little tip. Look at everything very carefully and go through in your head which next steps you want to do. It is also good to hold the battery compartment at the digital caliper and see if everything fits. For example, I have seen that there are small waves in the housing that I still have to make away with a modeling knife.

Now we can solder the two cables. Please pay attention to how the red and black cable must be soldered. After soldering the two cables, we can thread them through two small holes at the end of the battery compartment. The developer of the 3D model has really thought about this and I think it’s super good. This way I don’t have to drill two small holes in the battery compartment, which would cost the project unnecessary time again.

In order to solder the two cables in the right place later, we have to remove the button cell from the digital caliper. To do this, we push the cover of the battery compartment to the side and take the button cell out of the compartment with our fingers (or a small pair of pliers). This should not be difficult. This will allow us to examine the coin cell more closely. If it is empty, it will be thrown into the hazardous waste or taken to the electronics store. Please do not throw a battery in the normal household waste because inside a battery are toxic substances that can harm the environment.

Now we can connect the hot glue gun and let it warm up. We do this in the same way as with the soldering iron. In the meantime, we will work a little on the housing of the digital caliper and take a closer look at where exactly we have to solder the red and black cable.

If we take a close look at the battery compartment of the digital caliper, we can see some interesting facts. We see that you can only insert the coin cell into the battery compartment in one direction, so that its poles can touch the two small metal pieces the right way around. These two small pieces of metal are like our copper tape that we glued into our 3D print. So we have to solder the black and red wire the right way around. But how is that the right way around?

If we take a closer look at the lid, we see a small press-in. You can see a small battery, i.e. the button cell as it is inserted into the compartment from above. Unfortunately, this is too hard to see on the photos because my digital camera is not that good. On the top side of the coin cell is a plus (+) sign, so the other way around on the bottom side of the coin cell must be the minus (-) pole. So we know how to solder the cables.

Now that we have learned how to solder the cables, we can take care of another problem. There is a bit of plastic on the side of the case that we can easily cut off with a modeling knife. And by quite simple, I mean quite simple. It’s no great art and you don’t have to be afraid of a modeling knife.

After we have worked on the housing, we can finally solder the cables. Before we do that, we glue the new battery compartment to the digital caliper with hot glue, so that the cables don’t wobble during soldering. We shorten them with scissors to the right length. Leave a little bit of the length so that you have more room for maneuver. It is better to shorten the cable again instead of having to unsolder a cable that is too short. Be careful not to touch the housing when soldering, so that it doesn’t melt. Otherwise there is not much you have to pay attention to.

After this last step we are done and check our whole construction once again. For example, we pull on the cables and the soldering points, because they must be firmly connected to each other. it’s really exhausting to set up the soldering iron again when a cable is loose and solder everything again. Better to do it now, when the soldering iron is already on. The same goes for the hot glue gun. If something falls off now, we can just repair it quickly.


This was a super fast project and you should not need longer than a day. I also find good that my digital caliper now has more weight, which was previously too light in my hand. Instead of taking a disposable battery you can also use a battery that can be recharged. I will keep this in mind for my digital caliper, but for now this is enough. it is important to always upgrade small steps, so that you understand what you are doing. it is also always about learning something and not just to rebuild something. Please remember that.


After I had used the new caliper for a few days, a wire came loose at the soldering point. This happened because this spot was stressed. When mechanical components6 are heavily stressed, this is called stress. Over time, they can break, burst or bend more quickly. That’s why large companies always have their own departments that subject their products to continuous stress tests. I once worked for a while in such a research department, where gates were tested in a wind tunnel. German gates can withstand a lot of wind, because Germans love to build things that can survive a nuclear war. Most of the gates were sold to Florida in America and were on order for years.

However. After a few days, the cable came loose and I had to solder it back on. Actually, I wanted to drill two more holes in the lid and push the cables through there, but I had already used the lid for a kitbash project. A good way is to protect the cables with hot glue. Then they are less likely to break or come loose from the solder joints. This doesn’t look very nice, but it serves its purpose very well. If you rebuild the project again, it is also possible to remove the hot glue again. I hope that this now lasts a few months before I have to repair something on the caliper again.


  1. LR44 Cell↩︎

  2. I don’t know if it’s just me, but Nitter sometimes seems to have problems displaying content correctly. If you get a message that Nitter has not found the thread you just have to reload the page (F5) and then everything should be displayed. Nitter sometimes ticks around a little bit but for that you can display content from Twitter without scripts that are reloaded. Also, photos open in a new tab and not in whatever the Twitter developers call this frankenfront-end. Instead of letting psychopaths, conspiracy ideologues and trolls tear you down on Twitter, you should rather build a website on Neocities. There you have your peace and can concentrate much better on your own projects. Update: Since I wanted to change my web browser anyway, I have now switched completely to qutebrowser. It’s not better from a privacy point of view, but it’s also not as annoying, cumbersome, bloat and doesn’t have a xxMB update every week like FF. Anyway, this browser doesn’t seem to have any problems with Nitter. Another problem solved by accident. By, by Firefox. Stick your design changes up your digital ass. I hope the project goes bust so the managers at Mozialle can get grounded for once.↩︎

  3. AA / Mignon / R6 / UM3 / 1,5V-Zink-Kohle-Batterie↩︎

  4. I have seen that the Tedi Dollar Store also has an online shop. But I asked myself why I have to create an extra customer account, if I can pay with PayPal anyway. I’m used to PayPal that I can just store somewhere online without having to create a new account every time.Having to create a new account every time just because I want to order something small is super annoying. Oh, and an online store on this Internet should also provide the English language from selection option. Because, only a few people speak German on the Internet.↩︎

  5. If you don’t have copper tape, you can also use two small pieces of metal that you cut out of an old can, for example, but you have to make sure that this metal can also conduct the current. The best way to test this is with a multimeter or by soldering a resistor to an LED and then holding it to the battery. If the LED then lights up, you can use the metal.↩︎

  6. A soldered cable is not actually a mechanical component. However, it can behave like a mechanical object due to displacements and then also take on the negative properties that a mechanical component produces under load.↩︎

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