Now that we are using the truck, we really should have a way to monitor the batteries. Now I know most people just use voltage gauges, but it’s really not a very good gauge of whats really happening. A much better solution is to use a shunt.
A shunt is basically a large bus bar, with a known voltage drop across it. You connect all the negative sides of your loads and charger to one side, and your battery negative to the other, and it can measure the amps drawn into and out of the batteries because of the tiny voltage drop across the shunt. They use the negative side simply because its safe to have exposed negative posts, the exact same could be done with the positive side.
I had to make up some cables, I am using 2/0 marine cabling, its tinned thin stranded wire, crimp lugs on the ends and adhesive heat shrink tubing. It makes for very nice cables!
The meter is quite nice. You tell it how many amp hours your battery bank is and it tells you your percentage left. It can also show current amp draw, high lowest, deepest discharge etc. Its a nice unit. It all hook up with a piece of cat5 cable and RJ 45 jacks.
I installed it in the end of our tall cabinet, next to the thermostat. I’m really happy with this product. I originally was going to use a Xantrex unit, but this one is far simpler to set up and was less money as well!