I have been towing the 2013 Ford Edge for two days now. The first day the battery did not go dead but the second day it did. You can shut off the power altogether but the manual states to leave the car in the accessory mode. I would think removing the power may affect something or why would the manual state to leave the car in the accessory power position? I would be cautious about removing power until we find out why the power is recommended to stay on.
I use the BlueOx wiring harness and the SMI Airforce One braking system so i do not need accessory vehicle power for those items. The Ford recommendation may be general for systems that need lights and braking power. I think this may make a difference in the need for the accessory power (I don't need it for those items) but i am uncertain about other vehicle systems.
You can add a charging line to the towed vehicle. I am considering the "Toad-Charge" product. Is sells for $110 plus shipping.
Does anyone have any facts on the situation.
Thanks
Don