I wanted to get rid my digital caliper of it button cells.
So I recycled this idea found originally on http://www.trevorshp.com/creations/calipers.htm
and tried to improve it in the sense that it does not require anymore any specific cable. It now uses usb-c and charges through a regular phone charger .
X-acto knife cutting is required to make some room for the slide switch.
Hot glue allows to secure the circuit on the back of the caliper

The 150K regular resistor is just fine and is not heating.
Charging takes 10 to 20 seconds or so.
Improvements possible: adding a resistor or potentiometer before the negative of the caliper if voltage is to high and screen is difficult to read. (looks fine for me)

Happy hacking