addinf a switch in the +12V line from TV - Fiberglass RV
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Old 02-16-2018, 08:48 AM   #1
Name: Z
Trailer: Scamp
Posts: 73
addinf a switch in the +12V line from TV

I am in the habit of disconnecting the trailer from the TV when I get to location in order to not kill both the trailer and TV battery if we by chance leave something running.

I would like to simplify this process by putting a switch to break the circuit in the +12V line that comes from the TV and goes to the converter in the trailer before feeding the trailer and trailer battery..

If I look under the front bunk bed seat, I can see all the wires coming into the scamp from the TV harness and I can easily put a switch in if I had any idea what wire was +12V. Does anyone have a wire diagram for a 2010 Scamp 13 standard? or does anyone know what wire is the + 12V

Thanks all.
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Old 02-16-2018, 09:03 AM   #2
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Trailer: 1996 Casita Freedom Deluxe 17 ft
Posts: 450
Any shop can add a relay from the TV power connection that will disconnect the trailer when the ignition is off. This is by far the easiest way to do it. This isn't hard to do by yourself but a cheap multimeter will help immensely.

I also added a switch from the battery positive. It's a great addition and probably should be standard with the trailer since there's usually something that takes power even when everything is off. In my case, it was the propane detector. Not knowing the age and condition of your trailer, I'm not sure if a wiring diagram will be accurate so the best thing is to check the wire coming from the positive lead to the battery and then extend it to an easy location. You can buy a 25A switch at an auto supply store or through Amazon.
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Old 02-16-2018, 09:31 AM   #3
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Name: bob
Trailer: Was A-Liner now 13f Scamp
Posts: 3,209
luxux I added a switch outside my battery work great simple to do

good luck

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Old 02-16-2018, 09:55 AM   #4
Name: Neto
Trailer: Scamp
Posts: 81
I just unplug the connector.
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Old 02-16-2018, 10:02 AM   #5
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Name: Tony
Trailer: Bigfoot
Posts: 177
A lot of folks add a cheap, offshore made, Constant Duty Solenoid to their tow vehicle. Engine running is supplying power to trailer, engine off both batteries are disconnected. It is great when the solenoid works but they fail a lot. If going this route look at a quality CDS like a Cole Hersee or equivalent.
2017 Bigfoot 25B25FB
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Old 02-16-2018, 10:04 AM   #6
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Name: Ed
Trailer: Casita 17 ft SD
Posts: 183
There is an automatic relay that can be installed. When the TV battery reaches 12.6 volts it disconnects the TV battery from the camper.
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Old 02-16-2018, 12:37 PM   #7
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Trailer: No Trailer Yet
Posts: 683
I have a relay that opens up when the ignition is at OFF. The relay is actually controlled by the cigar lighter circuit, which on my vehicle is not powered when the ignition is OFF. Works great.

On the trailer, I also have a "master switch" to turn everything off when we're not camping. If you're in Canada, here's a link to Princess Auto's site for the 50A-rated switch I'm using (Canadian Tire also sells the same switch).
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Old 02-16-2018, 03:58 PM   #8
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The bad thing about a battery disconnect switch is if left off while traveling the emergency break away switch will not work because it's powered by the trailer battery.

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Old 02-16-2018, 04:21 PM   #9
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Name: alan
Trailer: looking
Posts: 264
IIRC the 12 volt power to the 7-pin connector is only on when the ignition is on in my '11 F-250. I can't find corroboration in the owners manual. If your tow vehicle connector wiring is the same and I understand your problem correctly then you need do nothing.
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Old 02-16-2018, 05:28 PM   #10
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The problem is there's no "standard" in how brands and models within brands work.
The best way is to know how your TV works and then remember to unplug it if necessary.
With more and more computers in vehicles it becomes difficult if not inpossible to just add a relay.
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Old 02-16-2018, 10:19 PM   #11
Name: Z
Trailer: Scamp
Posts: 73
No relay for me. Everything. Is handled thru the tow module (WV) I had to install and add to the on board buss (network) then code to my region (north america)

I can weird a DMM and CNA figure all this out come spring however I was hoping someone has a wiring diagram so I could work out a plan in advance.

I will just put in a simple switch in the line 12+ line from the TV.
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Old 02-17-2018, 01:04 AM   #12
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Name: John
Trailer: Escape 21, behind an '02 F250 7.3 diesel tug
Mid Left Coast
Posts: 2,673
the various vehicles I've had with factory row, the 7 blade connector is only ever powered when the engine is running. the various RV's I've rented, the 'house' battery is only charged by the engine when the engine is on, with the engine off, the engine battery is disconnected from the 'house'
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Old 02-17-2018, 02:59 AM   #13
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My vehicle came without any trailer harness, I rigged it up myself. The charge line is a dedicated 8 AWG wire that runs from the battery to the 7-pin connector, through a relay and appropriate fuses.
I have 2 items wired directly to the trailer's battery (they bypass the master switch). First, the breakaway switch for the brakes, so the brakes will activate with breakaway switch pulled even if the battery master switch is OFF. Second, my solar panels also bypass the master switch and will still recharge/maintain the battery when the trailer is parked with the battery switch at OFF. The solar panel controller has its own switch that allows me to cut it off if I need to.
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Old 02-17-2018, 04:06 AM   #14
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Trailer: Boler 13 ft
Posts: 1,880
My Tow vehicle 05 chevy trailblazer, had a factory installed Trailer fuse in fuse container in engine compartment. This fuse also ran a "+" post just outside the fuse box so when I wanted to add a charging wire to my 7 pin connector I ran a heavy wire from this post back to the proper pin in plug and this way it charges when engine is running and not when it is shut off with no draw on that post so it will not drain tow vehicle down
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