DB48X: HP48-like RPL implementation for DM42

[rprosperi]

As soon as cheap CR2032 batteries get below ~2.9V, they are unreliable. The DMCP is sensing the voltage under load and is attempting to display the actual voltage as seen with a load present, which is why it appears to be lower than the DMM is showing.

In any case, but a good quality CR2302 cell in (Energizer, Panasonic, Toshiba, etc.) and leave the cheap Chinese cells for other less demanding devices and you'll be OK.