Power (Current) Via 7 Pin Connector (2017 w/ tow package)

Very little. The only thing 12V that runs when on LP is the control circuitry, the LP valve and the igniter. It's super efficient running that way, but it's not practical while driving.

 

What's the issue while driving? The Cruise America RV we rented for two weeks ran the fridge on propane while driving - that's how the company told us to run it. The only extra thing involved was to shut off the propane while gassing up the RV.

 

The issue is that it makes fire. If you stop at a gas station to fill up, that fire might end up being only a few feet from a gas pump. Fire and gasoline fumes are a bad combo!


So anyway, coming back to this, I've designed an experiment that I am going to run when I head up to Kansas for a fly-in late in May. I'm going start the camper fridge on LP about a day before I leave, and stock it with water, gatorade and other non-perishables to let it pre-cool. Then before leaving, I'll check the battery voltage (at rest, nothing running) before heading out with the fridge running on 12V. After 5-6 hours, I'll stop for a meal and again check the battery (with nothing running, after disconnected and resting for a few minutes) and see what the voltage is.

That should tell me if the Taco is providing enough power to at least keep up with the draw from the fridge. Pre-cooling the fridge on LP and loading it up will help reduce the duty cycle of the system.

I suspect it will be fine in this context. I'd also suspect if the fridge were not pre-cooled, it might struggle to keep the battery charged up... but I'd rather pre-cool beforehand, since it takes a long time for the fridge to cool down anyway. I'll be making a video about the experiment and will post it.

 

It's not how much current is available, it's how much does the appliance draw, and can the wiring handle that load? The limiting factor is the gauge of the hot lead supplying power. For an 18 gauge wire (probably what the harness is using) it's 16 amps max recommended. For 16 gauge wire it would be 22 amps, and for 12 gauge wire, it's 41 amps. That is from the power source, via any relays; you can't just splice in a larger wire to a smaller one and get the ability to handle more current.

More variables to determine what the wiring can handle, such as resistance, which comes into play as the length of wire from source to appliance gets longer. Voltage begins to drop, and the appliance draws more current to compensate. If you draw more current than recommended through a conductor of a particular size, it tends to heat up. You might can get away with more current than recommended if it's a small increase, like drawing 17-18 amps through a 18 gauge wire, but you will get more heat, maybe just not enough to melt connectors or insulation. Or maybe enough. Check out this article, look at the "chassis wiring" column on the chart.
https://www.powerstream.com/Wire_Size.htm

 

The wiring gauge wouldn't limit current... it would just determine the point at which the wire would melt.

Given the fridge should draw around 13A, I suspect it will be fine.

 

Yeah, I know it's an old thread but I have the same question as the op. Has anyone found the answer? I just got off the phone with Toyota Corporate Tech Dept, and they didn't know. Viewing the above answers many don't understand the question. How many amps are available on the charge line pin(pin4) of the 7way trailer plug in the bumper from the charging system while driving? My small Norcold 3way refrigerator in my T@B 320 Outback trailer draws 11.7 amps at 12vdc, per the specification sheet just received from parent company tech dept. The reason we ask is when running the trailer refrigerator, the trailer battery goes down(almost dead) significantly during a 9-10 hour drive, ie: truck not putting out enough juice!

 

Well, I guess I was wrong that you would get more useful info over here but I think I understand your question better now. I doesn't sound to me like you're getting any 12vdc from the taco to the trailer. Have you checked for voltage at the 7pin connector?

 

Yes, good voltage at the connector. Both truck, trailer batteries checked good. The problem is the amperage output at the plug, not voltage. Only way to verify amperage is rig up something in series at the plug to enable metering. But I’m concerned this will screw up truck electronics in some way. I’ll try Toyota Corporate again this week. I don’t accept “I don’t know” answers well from pros.

 

But if your fridge is killing the Battery in 9-10 hours then you are not getting any power to the battery. I think you need to check to see if you are actually getting power to the battery. Try this... disconnect the battery, then with the truck hooked up and running see if you have 12vdc at the trailer.

 

Done that, all goo

Done that, all good. Good voltage all the way to the battery and refrigerator. I just don’t have a way to read the amps. I still suspect not enough amperage from truck plug to keep up with amp draw of refrig.

 

Really it's not going to be a problem. It's done all the time and is the whole purpose of the hot lead to the trailer. it is also the reason that you get a bigger alternator with the tow package.
You have the tow package don't you?