Your model is made by Magnum Energy. Your model is an INVERTER only. NO 12 volt charger. So, to answer your question, DO NOT LEAVE THE INVERTER ON. Only turn it ON when you need to run the Refer when NOT connected to Shore Power. If left ON, then if you lose 120 shore power, the Inverter will drain your existing battery Power in about 24 to 36 hours. Also, I do not advise customers to leave Inverters ON unless you want Inverter Power. The reason? Inverters (stand alone or Inverter/chargers) are out of sight and out of mind. Some RV'ers ALL THE TIME, forget they had the Inverter ON (stand by mode) and when they park to store, the Inverter then is ON and drains the batteries in a few days. How do I know this? Simple. About 75 percent of my motorhome customers drop their unit off for service and after a few days the coach batteries are either DEAD or way below 11 volts. BECAUSE they left the Inverter/Charger ON. They forget. Out of sight and out of mind. Fulltimers rarely have this type problem as they are in their units 24/7. Doug