[jclark003]

Make sure your battery charger is off or you will show the same charge voltage on both banks. It’s helpful to use a digital volt meter, checking voltage at alternator battery terminal with both engines off and again with just port engine running. This will tell you if alternator is charging. If you do see charge voltage, leaving the port engine running put the meter on the other alternator battery post and see if the same voltage is present. If so batteries could be tied together.