Originally Posted by Dockhead
....I just had everything rewired by an expensive professional marine
electrician to go to one master negative bus bar, so in theory, the Victron meter should be getting all of the loads. But in practice there are some exceptions -- the engine-driven alternator
, for example, doesn't get its negative through the bus bar, and the Victron doesn't count amps added by the alternator
Many battery monitors do not work accurately because the shunt needed to measure the current
is often installed incorrectly. It must be as close to the battery as possibly – usually on the negative post – and a new bus bar must be installed immediately after the shunt. All other battery negative cables
MUST go via this shunt. With multiple batteries in parallel, and not all in the same location, it is often difficult to know what wires are going where.
With a battery monitor
installed the bus bar becomes the new battery post for the service
bank, so the starter battery negative must also be connected to the bus bar not to a service
battery negative terminal. This error is probably one of the major causes of battery monitors not reading the charging
amps. This will often happen when the starter bank has priority and is charged first because the charger
positive and negative cables
will be connected to the starter battery. When the split charging system supplies positive volts to the service bank the charger
will supply the negative arm via the starter battery post and then to a service battery negative stud. For the battery monitor to measure the service battery charge the starter battery negative must go through the new shunt.