Travel Trailer Tech Question

[lawnspecialties]

I've have often done something that I used to caution myself not to do. Everytime it's just because of absent-mindedness.

Is it a potential problem to have your trailer plugged into a power source while having the 7-pin connector plugged into your truck? I wonder if it could cause camper problems or even truck electrical problems? I must admit, I do it quite often.

We are heading down to Myrtle Beach this afternoon and while loading up, I realized I was doing it again. The truck and trailer are all hooked up and ready to go. I did that yesterday. But while loading, I plugged the TT into my 30 amp outlet on my shed so we have power to do everything we want. I never even thought of unplugging it from the truck.

And of course, when we head down to the Fort, we usually pull in at a campground for the night to break up the trip. I leave everything hooked up but again, never even think to unplug it from the truck.

 

[LarryJ]

I've have often done something that I used to caution myself not to do. Everytime it's just because of absent-mindedness.

Is it a potential problem to have your trailer plugged into a power source while having the 7-pin connector plugged into your truck? I wonder if it could cause camper problems or even truck electrical problems? I must admit, I do it quite often.

We are heading down to Myrtle Beach this afternoon and while loading up, I realized I was doing it again. The truck and trailer are all hooked up and ready to go. I did that yesterday. But while loading, I plugged the TT into my 30 amp outlet on my shed so we have power to do everything we want. I never even thought of unplugging it from the truck.

And of course, when we head down to the Fort, we usually pull in at a campground for the night to break up the trip. I leave everything hooked up but again, never even think to unplug it from the truck.

The only two issues that I'm aware of is that having your trailer plugged in you will back feed the trailer charge ckt on most TVs if you have the TV key on and the same even w/o the key on in the brake circuit. I don't think you can actually do any damage by having the TV hooked up to the towed vehicle and also on shore power, but someone else might find an issue that I just haven't thought about.

For about the last 30 years, I have never made it a practice of making sure that I have the TV disconnected from the TT when the TT is on shore power and have never encountered a problem that I'm aware of.

How's that for a sort of non-answer

Larry

 

[bigdisneydaddy]

I do know that on GM pickups the 12v feed for the trailer battery is a "constant on" meaning it is connected to the battery at all times. This became a concern for me since we frequently use the battery while stopping at rest areas. We will use the furnace while sleeping and the fan consumes a fair amount of power. I wanted top avoid draining my truck batteries while doing this. My understanding is that the converter supplies 12v to the battery when connected to 110v in order to keep the battery at a full charge, since your truck is connected it would stand to reason that your truck batterie(s) are being charged as well. Unless you truck batteries were weak I wouldnt see a problem with it. I ended up rewiring my 12v trailer feed on my truck so that it only provides power when the truck is running, that way my truck batteries are isolated when we are still connected and using battery power in the trailer.

Scott

 

[clkelley]

I asked this very question to our T@B group on my T@B as when going down to Disney, I also stop for an overnighter each way and don't disconnect, just plug in the electric and go to bed.

I also have the charge wire to my TV, but added the isolation relay so that it is only charging when my truck is running.

I was told it is no problem and if you don't have the isolation relay, then the power at the campground is also charging your TV.

 

[LarryJ]

I do know that on GM pickups the 12v feed for the trailer battery is a "constant on" meaning it is connected to the battery at all times. This became a concern for me since we frequently use the battery while stopping at rest areas. We will use the furnace while sleeping and the fan consumes a fair amount of power. I wanted top avoid draining my truck batteries while doing this. My understanding is that the converter supplies 12v to the battery when connected to 110v in order to keep the battery at a full charge, since your truck is connected it would stand to reason that your truck batterie(s) are being charged as well. Unless you truck batteries were weak I wouldnt see a problem with it. I ended up rewiring my 12v trailer feed on my truck so that it only provides power when the truck is running, that way my truck batteries are isolated when we are still connected and using battery power in the trailer.

Scott

See that's very different than what Ford does at least in my Van. The trailer charge ckt is on a relay dedicated to that and is only closed when the ignition is on. In fact the relay is not even installed from the factory, it comes with the brake controller pigtail. I changed things and used that charge ckt for my aux rear backup lights that are a god send and ran a completely separate trailer charge ckt that goes thru an ammeter that is controlled by a relay and switch so that I can charge my trailer battery when traveling when I want and only when it needs it. I also used either 6 or 8 ga wire for that ckt, whatever the max size I could stuff into the 7 pin connector on my Van and it was a really tight fit and at least a ga or two larger than the factory wiring. In my experience this has helped making my trailer battery last longer since the really long runs on that ckt along with the trailer plug connection drops the voltage enough that battery boil off for me was an issue.

Larry

 

[bigdisneydaddy]

See that's very different than what Ford does at least in my Van. The trailer charge ckt is on a relay dedicated to that and is only closed when the ignition is on. In fact the relay is not even installed from the factory, it comes with the brake controller pigtail. I changed things and used that charge ckt for my aux rear backup lights that are a god send and ran a completely separate trailer charge ckt that goes thru an ammeter that is controlled by a relay and switch so that I can charge my trailer battery when traveling when I want and only when it needs it. I also used either 6 or 8 ga wire for that ckt, whatever the max size I could stuff into the 7 pin connector on my Van and it was a really tight fit and at least a ga or two larger than the factory wiring. In my experience this has helped making my trailer battery last longer since the really long runs on that ckt along with the trailer plug connection drops the voltage enough that battery boil off for me was an issue.

Larry

We had an F350 chassis cab at work that came with the seperate relay for the trailer. I actually like that setup because it doesnt allow the batteries to equalize as fast. The conversion on my Chevy was easy, the trailer feed is on a post in the underhood electric, I just installed a relay and connected the wire to it. Anyone with basic wiring tools can do it.
Scott