Show me your battery monitoring set-up..

[IdahoMan]

There is the factory cluster gauge on our trucks (upper left-hand of the instrument panel) that monitors the battery when the key is truned forward. It has "8"----"13"----"18" on the face. I guess it's fine for what it's for, but I wonder if there is a better/more-precise gauge out there..

A 2nd battery will be usefull for accessories/camping. I'll be wanting to keep an eye on the battery's voltage level, and the amperage that is being drawn from it. The empty guage spot on the lower left-hand of the instument panel looks like an ideal spot if I could find an accurate guage of some kind that will fit there (concept).

What's your set-up for battery monitoring?
Is there a reputable, precise gauge brand/type you recomend?