There is so much confusion over the use/store switch, and as a result you'll find plenty of discussion about it all over the site.
In general, if you have the switch in the "STORE" position, the 12-volt converter will power all the 12-volt systems when plugged into AC or when running the generator. When the switch is in "STORE", however, your battery (or batteries) will NOT be charged while plugged in.
You only need to put it in "STORE" position if you are not going to be using the RV for any length of time. It minimizes battery drain - just be aware it does NOT eliminate battery drain as a few other small things are still connected.
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