Originally Posted by skipmac
Not sure whether I would call it before or after but connect the starting battery ground so current
to the start battery does not pass through the shunt. You want the monitor to only measure the amps going in and out of the house batteries.
If your bank features a parallel switch or combining relay the in-rush flows and equilibrium current flowing between banks when connected will throw off your monitors calculations just like a bilge pump
that by-passes the shunt would. If the start battery is on the battery side of the shunt it should be moved..
If your second battery has the capability to be either a load or a charge source, via "combining banks", you should treat it as such. Either way you are NOT "monitoring" the second battery, just the bank the monitor is connected to, and you are only treating it as a load or charge source like any other load or charge source that could change the state of charge on the bank being monitored..