Battery monitor and VSR

Hi Will, I'm not great on this stuff but I'm confused. If your two batteries are in parallel, that sounds like a single battery bank, but normally a VSR is used to charge a second battery or bank while keeping its discharge separate from another battery or bank. What am I missing here?

PS Glad to hear about the relatively new BMV 712 Smart. Pretty cool:

https://www.victronenergy.com/blog/2017/09/18/bmv-712-smart-battery-monitor-with-bluetooth-built-in/

I maybe wrong about batteries in parallel. see this post with wiring diagram on the hull truth website.

https://www.thehulltruth.com/marine-electronics-forum/908735-battery-monitor-shunt-location.html

Hi Will,

I think I understand what's going on now, and I also reformatted your scan so that Panbo readers can see it better:

https://www.panbo.com/assets_c/2018/02/Boston_Whaler_23_stock_battery_and_engine_wiring-16119.html

It looks like you have two battery banks and one VSR (Voltage Sensitive Relay) or ACR (Automatic Charging Relay) so that your engine can charge both batteries without letting the engine start battery drain into the house battery.

I'm pretty sure that the Victron shunt should be installed inline with the ground cable to the house battery. In other words, you need to take the black ground cable off the battery, attach it to the load side of the shunt and get a new short cable to go from shunt to battery.

According to the schematic your house battery ground cable goes to the engine start ground pole which is then cabled to ground bus bar. That's unusual in my experience but I don't see a problem as long as your shunt is in the section between the batteries. Otherwise you'll be measuring the current loads on both batteries but won't know the State of Charge of either.

Please note that I am not expert in this department (or any other), so it would be good to double check with a pro.