In the 7 pin harness on the tow vehicle there is +12 volts going to the battery thru the 7 pin cable in the camper thus charging the battery when you have the trailers plug plugged into your tow vehicle -
when the tow vehicle is running that is when the battery in the camper is being charged unless it is disconnected from the tow vehicle and is hooked in the camp site service which is then being charged by the battery charger or inverter / charger.
neither portion of the 7 pin harness is dead because they both have voltage on them unless the + plus side of the battery is diconnected - the trailer plug is enclosed so no wires are exposed and the 7 pin plug on the tow vehicle usually has a cover so no connections are exposed there either
does that answer your question?
2011 Rockwood Mini Lite 2306 - Matt
2004 Dodge Ram 1500 Qaud Cab 4x4 with 35" tires and 3.92 gears, Dynatech Longtube Headers & Fabtech 6" lift + Superchips with shift Tuning
Nights Camped 2011 (37) - 2012 (16)-2013 (2) -2014 (5) -2015(0)
USMC 91 - 95 - F/A-18 Aviation Ordnance