Truck battery drain when 5ver connected?

[kdubinwa]

Here is what I know about my trailer setup . . .

If I leave my trailer plugged in to my truck . . . the trailer will draw juice off of my truck battery until it is dead.

Ie. - inside trailer lights, and anything else 12-volts, will run off of the truck's batteries first, then trailer batteries second . . .

Moral of the story:

Don't leave your trailer plugged in to your truck when boondocking unless you have a back-up plan for a jump start!

Yep. That is the very reason everyone should use a run only circuit for a making a trailer connection. I really don't want to operate with an always unplug mandate. I also have a pickup truck camper and access to the bed plug is not easy after loading the camper. I'll get this figured out and share what I find.

 

[kdubinwa]

Problem solved. I discovered that the wire used to trigger the compressor relay was tapped to the 12v acc charging line for the trailer receptacle. It is not powered when the truck is not running UNLESS the trailer plug happens to be plugged into the receptacle and the trailer batteries are in-line. I just switched the compressor relay trigger to a new 12v feed run from a spare run/acc wire in the cab. All better now and my air bag compressor no longer turns on when the ignition is off regardless of whether or not the trailer is plugged in.

Thanks for helping me think through the possibilities. It helped the trouble shooting.

 

[Lynn1130]

Don't leave your trailer plugged in to your truck when boondocking unless you have a back-up plan for a jump start!

And diesels do not jump start well at all.

 

[Bones]

Perhaps a battery isolator will help so you can't drain your trucks battery but your truck can charge the camper batteries when running