Hard To Find - How Much Current Via 7 Pin Trailer Connector

Trying to find out how much current can be pulled by a trailer connected via the 7 pin connector on a '17 with the towing package. I couldn't find that documented anywhere.

 

https://www.google.com/search?q=max...j0j4&hl=en-US&sourceid=chrome-mobile&ie=UTF-8

https://www.etrailer.com/question-238830.html

 

I think it's fused at 7.5A

 

That stuff is easy to find. I'm not asking about wiring gauges and how much the wiring COULD carry. I can figure that out easily. I want to know how much power can be pulled by a load connected to the 12V circuit.

Specifically how much. Not what might be based on the wiring. Sure, knowing the gauge of the wire would at least provide a limit, but is that the same amount of power (current) the electrical system will allow?

 

I’m confused what you mean by “electrical system”. If you figure out the gauge and calculate the limit, and look at what it’s fused at, well, there’s your number.

 

Ok, maybe the reason I'm trying to find the info is going to help.

The camper I have (actually both of them, one will be sold, one is new) has a 3 way fridge. It can run off of AC, DC or LP. I know it uses 160W when on either electric system. At ~13V, that's 12.3A of current.

Which brings us to the question - how much current can I pull from the truck via the 7 pin jack?

While I understand how all this crap works, it's come up in the camper group I'm frequenting now. "I towed my camper with the fridge on DC power, now my camper battery is dead!" Well, yeah, that's because your tow vehicle can't provide enough power, and the extra was drawn from the battery. One feller says he does that all the time in his Jeep somethingorother and I commented it must mean his vehicle puts out enough current that it's either not draining the camper battery, or it's not enough that he notices it.

Which got me wondering... "I've got the fancy towing package with the beefier alternator... how much current can I draw from the truck? Because it would be pretty damn neat to be able to run the fridge on DC while I'm driving. Cold food staying cold = good".

If it's insufficient, which it probably is... I may wire up a fuse and a larger gauge wire, with some Anderson PowerPole connectors, since I use those on the battery, then just plug the camper battery into that while towing. Problem solved.

 

It’s called electrical theory for a reason. The amount of power available depends on your battery (and the ability of your alternator to recharge it), the total demand of other accessories in your truck, and the gauge of wire to your fridge (don’t forget about the start-up of the pump on the fridge). If it draws too much, you will either kill your battery regularly or start fire to your truck.
Best bet would be to use the wiring to the accessory plug in the bed. The trailer wiring is not designed to carry a constant high demand load.

If you want to experiment, hook it up and use a multimeter to make sure your battery is being recharged sufficiently while the truck is running - you could also install a voltmeter in the cab to monitor the battery.

 

Looks like 40 Amp fuse on the trailer battery connection to me, per the schematic. (Haven't looked on the actual truck)

 

That 12 amps is the inrush amperage the compressor motor uses to start. The running amps is much lower.

 

Not on a three way. It doesn't have a compressor. It has a 160W heater.