Measure voltage on the battery that powering the Mkr

I have a battery powering my Mkrzero from Usb using solar manager.
I want to measure a powered battery.
Would you mind helping me?

Not too hard to do, however there are thousands of answers we could give you and most will be wrong. Post a simple schematic, not a frizzy thing showing all power and ground connections. A hand drawn one is OK. Also post links to the technical information on eac hardware part.

Nice pictures but no schematic. I do not have the time nor inclination to go through all of that data hoping to find a schematic.