There is a converter (XADC) that coverts from 110v to 12v It contains all the 110v breakers and the 12v fuses. It is always on. It makes a little noise when it is charging the batteries.
The Xantrax Inverter is only used when you do not have 110v power. It is operated from the remote panel. This should be left off. If you need 110v to the outlets when you are not plugged in to 110v power just touch the switch and it is on. When done, touch and it is off. No reason to have this on unless you are not plugged in.
It makes a littlemore noise when you draw higher power.
I was just dry camping for a week. I used it once to make some waffles with a 700W waffle iron. Worked great, took the batteries down about 10%.