Does the battery get run down.....
I have posted this concern or all the battery operated systems save two, (Invisible brake and US-Gear Unified Brake Decelerator) both of these systems, their designers have taken the power needs into account and included a way to charge the battery in the towed.
Several folks always point out to me "I've towed clear across the country (2-3 thousand miles) and the battery did not go dead.
Well, Bully, brand new battery, full capacity,, Others, with older batteries,,, Not so lucky.
I see someone has suggested the Towed Charge system... I second that suggestion.
My current towed does not have and electric system (i am trying surge brakes) but I still have the towed charge line in place from the US gear system so I adapted it to the new towed,, also put a 2nd port on the front of the motor home so I can charge the car if parked in a campground for a week of non-driving.
Home is where I park it!