Leah:
Off/On? Your Charger is the same unit as your inverter. The only On/Off switch you have is for the Inverter side, which only comes into play when you are NOT plugged in. When you are plugged in, your charger is operational without you doing anything. When you are plugged in, your inverter is NOT operational, regardless of the switch setting. You should keep your inverter switch Off, when not plugged in, unless you want to run AC loads without starting your generator. OK for small loads, for a short time, but generally, too much inverting will deplete your house batteries. If you are always either plugged in, or driving (where the alternator picks up the slack), you won't need to worry about it, as your batteries will keep up.