question about trailer connection

[markabby]

I noticed that when i plug in the 7 prong into the truck, there's constant power going to the trailer battery. I keep it unplugged if left on over night.

Is there any way to turn that off and only send power when the truck is ON? I thought it might drain the truck battery if left plugged in over night. (?)

If it matters, the trailer battery if for the brakes only in case it breaks away and the battery is a 12volt from a lawn mower

 

[joesstripclub]

I don't think I've ever had it drain my truck battery while sitting. I think it only charges the battery while the truck is running, though I could be wrong. I know my old trailer interior lights would only work when connected so maybe that is the same power wire. I left the interior light on at night one time and that definitely drained my battery. That breakaway battery shouldn't need enough power to drain your truck unless the battery is in bad shape and continually charges.

 

[crash68]

@markabby you would need to add something like an isolation solenoid to turn the +12V off going to the plug or just unplug it when parking overnight.

I think it only charges the battery while the truck is running, though I could be wrong

There's just a fuse direct from the battery that goes the +12V in the 7 pin plug

 

[Tulecreeper]

I don't think I've ever had it drain my truck battery while sitting. I think it only charges the battery while the truck is running, though I could be wrong. I know my old trailer interior lights would only work when connected so maybe that is the same power wire. I left the interior light on at night one time and that definitely drained my battery. That breakaway battery shouldn't need enough power to drain your truck unless the battery is in bad shape and continually charges.

^^^ That ^^^

 

[GTyankee]

usually, a Battery Isolator is used in vehicles with more than one Battery.
Usually both batteries are under the hood of the vehicle.

The Isolator would be mounted near the Auxiliary battery.
So you would have to open the hood to throw the switch

It is just as easy to unplug the trailer at the bumper & you would always check your trailer hitch as you walk by, or even if you intend to move a vehicle

 

[markabby]

i just thought when the truck was turned off, everything was off. The LED light on the trailer shows constant power. It has a new diode, so the LED light is only sensing power from the truck.

for now, i'll just unplug it if it has to sit a for a long time.

thanks for the input.

 

[2003F350]

Yeah I've let them sit overnight with no issues as long as the batteries on the trailer (whether a big marine/RV battery or just the breakaway battery) are in good shape. If they're questionable then yeah, it's a good idea to unplug them or you COULD end up with a dead/weak battery - not necessarily WILL but could.