I have built an Orion Smart 12 / 12-30 (B2B Charger) into my Camper RV. When I turn on the external AC charger, the Orion Booster detects the external charging voltage as an alternator load voltage. I am assumed that the Orion Smart has a vibration sensor to clearly identify the alternator voltage from the external charge current. All other structures, such as parallel connection and charging of the starters and consumer battery work properly.