Dear Boat Doctor,

I would like to install a battery monitor that will show the state of the charge of my batteries. I have basic mechanical and electrical skills and would like to try to install it myself. What’s the best way of doing it?

Jerry Lewellen

Buffalo, New York

Dear Jerry,

These systems, which work like a fuel gauge for your battery bank, are quite handy. They are easy to install but require a little electrical knowledge. The systems require two inputs: battery voltage and system current. 

The voltage is straightforward, just connect the positive output of the battery bank to the voltage input. Current is trickier, and you need to install a shunt into the negative side of the battery bank. All the negative returns need to come back through the shunt. You will have to sort out where the negatives are and how they connect to be able to properly locate where the shunt should be installed and properly size cables.

Mount the display of the system near your electrical panel, perhaps in your nav station. The gauge connects to the shunt with a cable that looks like a phone or network cable. You’ll need to route the cable from the shunt to the display.