Trailer Wiring????

[79Challenger]

I am wiring a new trailer plug. Going from a 6 way to a 7 way. Looking to include the trailer power in the vehicle charging.
Where should the power come from? Going from the battery would make it hot all the time. Right off of the alternator?
Any one havw any knowledge to share?

[Trailer Park Casanova]

Click this link:
http://www.marksrv.com/wiring.htm

[Jetaholic]

I am wiring a new trailer plug. Going from a 6 way to a 7 way. Looking to include the trailer power in the vehicle charging.
Where should the power come from? Going from the battery would make it hot all the time. Right off of the alternator?
Any one havw any knowledge to share?
Right off the alternator would be hot all the time as well.
How much current draw will you need for the hot wire? You can probably either find or run a keyed +12VDC wire on the truck and supply your +12VDC off of that.

[79Challenger]

Right off the alternator would be hot all the time as well.
How much current draw will you need for the hot wire? You can probably either find or run a keyed +12VDC wire on the truck and supply your +12VDC off of that.
By hot all the time I meant even when the truck isn't running. This would let the trailer draw off of the truck while parked. But off of the alternator would only be hot while running... right?
I thought of tracking down a keyed powere source, but would this be heavy enough to help charge the trailer batteries? Especially without any fuse problems?

[Jetaholic]

By hot all the time I meant even when the truck isn't running. This would let the trailer draw off of the truck while parked. But off of the alternator would only be hot while running... right?
I thought of tracking down a keyed powere source, but would this be heavy enough to help charge the trailer batteries? Especially without any fuse problems?
OK...the hot wire on the backside of the alternator IS hot all the time. This terminal is connected directly to the battery. What happens is that when the key is off, the battery voltage is on this terminal. Once you start the vehicle, the alternator starts putting out on this terminal to charge the battery, so you now have alternator power available on this terminal, which is about 1.5-3 volts higher than the battery voltage. Once you shut the vehicle off again, the alternator no longer puts anything out, and you're left with the battery voltage on this terminal. So in effect it is hot all the time.
I'm not sure if your alternator is up to the challenge of charging multiple batteries though. You may have to go to an alternator that is capable of supplying more current. As far as how much more current per battery I'm not sure. But I'm thinkin' you're gonna need some kind of a seperate plug than the trailer plug, say a 50 amp twistlock type connector that you would normally use in a 220VAC application, fed by battery cables to be able to supply the current to the additional batteries. I would run these cables coming straight off the battery.

[79Challenger]

^^^^Yeeeooowww. I was under the impression this was somthing all of the toybox guys did.

[Moneypitt]

The charge wiring doesn't need to be much more than 10 ga. The trailer batteries will pick up any heavy load. I don't think you want to pull all the trailer power through 10 ga. unless you have trailer batteries/battery. I think the late model stuff has conectors under the dash you hook up to finish the trailer package wiring, including the charging system for the Aux. batteries, and back up lights. That wiring site was great, printed it out for future reference.............MP

[Misogynist]

If you are running an auxiliary battery in the trailer and want to charge it with the tow vehicles charging system, I recomend that you get a diode block for the auxiliary battery. That way the power only flows one direction to the trailer battery. If you don't have a diode, the current from the second battery will come back to the source and then down to the starter during cranking. You don't want a lot of current passing backward through a 10 gage wire and the trailer plug connector. I'm assuming you have the auxiliary battery for "electric over hydraulic" or electric brakes.

[Beer-30]

Just come off of the alt with a 10 GA, to a Bosch type relay on the firewall. 10 gauge from the output of the relay to a waterproof fuse or circuit breaker, and then to the trailer plug at the bumper. Wire the trigger for the relay from an ign switched source, and you've got it. When the key is on, the circuit will be hot. When vehicle is off, 12v from veh is cold, other than the 12v back from the trailer, which will just dead-end at the open relay. Simple and safe.

[Cheap Thrills]

If you are running an auxiliary battery in the trailer and want to charge it with the tow vehicles charging system, I recomend that you get a diode block for the auxiliary battery. That way the power only flows one direction to the trailer battery. If you don't have a diode, the current from the second battery will come back to the source and then down to the starter during cranking. You don't want a lot of current passing backward through a 10 gage wire and the trailer plug connector. I'm assuming you have the auxiliary battery for "electric over hydraulic" or electric brakes.
The correct way ! But dont walk into the parts store and ask for a diode block most of those numbskulls wouldnt know what a diode was if it jumped up and bit em in the ass.. ask for a Battery Isolator. here's a diagram on how to wire it. http://www.***boat.com/image_center/data/520/1127battery_isolator-med.jpg
you definately need some "House" batteries for the trailer.
T.

[Beer-30]

That would work too, whether dual batts on the two vehicle or not. Isolator would become the relay, and close the circuit with either ign or 13.5+. Batt would connect to one side of iso, trailer plug to the other side.