this may of been mentioned, but I can't remember if the battery switch needs to be off or on when I connect to my truck so the battery can charge while I'm driving
ON. And you should always have the battery on when towing. Reason being that if the trailer should come detatched from the truck the battery is needed to engage the trailer brakes.
I pulled out the switch and have left it that way since purchase of my unit. There doesn't seem to be any reason to push the switch in to disconnect the 12 volt system from the battery.
__________________
2012 Fun Finder XT 276 Toy Hauler & Harley Davidson Ultra Classic with Condor wheel chock
2014 Dodge Ram 2500 AT 4X4 Crew Cab 6.4 L Hemi, 373 gears, tow package, Rambox option, Revolver X2 tonneau cover, Equal-I-zer anti-sway hitch.
It's also a good idea to turn off the switch when you are not plugged in, and not using the trailer for several weeks. That way, nothing drains the battery when the TT is sitting un-used.