I am using intel nuc for my robot and powering it up with a 14v battery(on full charge it 14 and after discharge it's 12.5). By any way can I know the battery values from NUC as it is directly connected. I am using ubuntu-18.04.
Also, you really should be using 19V.
And, you may want to review this thread:
Doc (not an Intel employee or contractor)