@ surveyor Mike...I'll second garbonz entirely and add that Victron makes an excellent battery monitor and if you or others boondock a lot...you won't believe how useful they can be when you know your amps remaining...amps being used...time to go to 50%...and % of charge and charging amps when charging. Along with the usual volt readings of course.
The bmv600 monitors all of this on one BANK of batteries. Their BMV602 also lets you monitor voltage ALONE on your chassis battery. BMV-600S series - Victron Energy
Installation is easy. You simply take ALL the stuff that is attached to your negative battery terminal and bolt it on to one end of the supplied shunt. The other side of the shunt goes to the negative battery terminal with a cable. Attach the positive wire supplied to the positive post and the shunt. Finally... you plug in the telephone wire to the shunt and the actual meter and you're in business.
I understand Trimetric also makes a good monitor but I can only speak from experience about the Victron.