I had one of the £10-15 ones that infest fleabay. It worked for a while, then got increasingly stroppy I think due to poor battery contacts, which I couldn't molish.
Binned them in frustration and bought a set with a dial gauge to 0.01mm. Old tech, works perfectly. This cheap Chinesium stuff made to a low price is crap. No surprise there then, but I didn't want to pay £50 or more for something I used occasionally. Having said that I use my dial gauge calipers several times a week. They are perfect.