Image Caption
Two way switch.
How to wire in the BMV-712 in this set up
asked
How do you wire a BMV-712 to house and start batteries with a two way battery switch with 1, 2, Both outputs.
This is not a good plan. The BMV makes calculations based battery capacity and moving the switch between positions changes the capacity (house bank alone, both, starter battery alone). Plus the BMV makes state of charge calculations based on the current flow in and out of the battery. Again, changing the position will result in calculation errors.
The best way to do this is to put a BMV on both batteries. Each will then show you the state of charge of each battery by itself.
Many people will ignore the SOC of the starter battery and put a battery monitor only on the house battery. The rationale is that monitoring SOC for the house battery is the key to power management. The starter battery is only used for starting and emergencies.
You might also consider a DC-DC charger to charge your house battery from the alternator. It's safer that way. Directly charging the house battery from the alternator could damage the alternator.
