Some more background on my unit. I have a 2017 Newmar Ventana with a residential fridge. The coach will be parked at a storage facility and covered. I don't know what else he has on the 15A circuit and he wasn't sure. The is another RV 50A RV with the appropriate adapter probably on the same ciruit. I do believe the inverter has to be on to charge the house batteries. Not sure of the engine battery. This is the first time I'm storing the RV at this location. Again thanks for your input.