Everyone who has to measure fine things in the workshop knows these calipers sold for a few bucks on e bay or in DIY- malls.
Those calipers are fine, accurate enough for home workshop use and as biggest advance easy to read. (especially if you reach 45 yrs in my case ;)
The big disadvantage is the button cell with 1,5 Volts, who ran empty in a short time. As you know, mostly when the next store who sells button cells, is many kilometers/miles far away.
So i hacked quick and dirty a big power source, an AAA Battery, on the caliper. Now it will last for years with the option, to have a common replacement battery in the house.
Step 1: Things You Need..
The things you need, should be available in every workshop.
an AAA Battery (1,5V)
two fine wires, if possible in different colors
Sandpaper , fine above #200
two neodymium magnets with 10mm diameter, 4 mm holes and 5mm thick.
Soldering iron around 25 W and electronics solder
Hot glue gun
Step 2: Fuse It Together..
Remove the isolation from the wires a bit with a wire stripper and solder it gently on the battery clamps of the caliper.
Keep in mind that the middle pole is "-" and the outer is "+" For easy recognizing you can use a red wire for "+"
Sand now the both poles of the battery a bit for better soldering.
Sold the other ends of the wires to the depending poles of the battery. The soldering act on the battery poles must go quick or it will damage the battery.
If you not so familiar in soldering and fear that the battery will explode, after five minutes soldering, you may fix the wires with two neodymium ring-magnets.
Just wrap the stripped ends of the wires through the holes and clip it on the battery's poles.
The main disadvantage of this method is, that the strong magnets will soak every fine metal swarf on it, while you lay the caliper on the workbench. After a few days they will look like hedgehogs or shorten circuit the battery.
If you are mainly wood-crafter, this will be no problem for you ;)
As last step glue the connected battery on the backside of the caliper and enjoy an always usable caliper in your shelf..