For precise monitoring of the service (house or main) battery bank, a shunt is necessary. Being informed about your battery status is not only for electrical enthusiasts – it is about your safety! In a case of emergency, a power loss can end up badly.
We highly recommend using shunts for heavy consumer batteries like a bow and stern thruster, anchor winch. Such consumers can discharge your batteries significantly in a matter of moment, which means they can also damage the batteries quickly if they are not sufficiently charged.
If you have separate batteries that you only use to start your engines, monitoring only battery voltage will be enough in most cases.