How to check if the TV is charging the 5er

With the truck running and connected to the trailer, check voltage at the trailer batteries... Should be somewhere between 13 and 14 V

In my case I just don't get alot of charge at the trailer batteries coming from the TRUCK Alternator when driving. I only plan for my truck alternator system to give me TOP OFF DC CHARGING back to where my TRAILER BATTERIES are installed. Also your INVERTER will want to pull alot of current from the TRAILER Batteries even just running the fridge.

I suspect you are going to need more batteries on the trailer side if you will be running the INVERTER alot.

Using a multimeter across the battery terminals should show 12.6-7VDC when the batteries are fully charged. If the truck motor is running or you are connected to SHORE POWER the multimeter should read 13.6VDC or more (Up to 14.4VDC in my case) depending what charge mode it is doing at the time.

Just my observations here...
Roy Ken

With a propane refer just run it on propane.

Inverters can draw a lot of amps and most likely more than you TV can supply. In that case solutions are involved.

If your TV is fully charged the alternator will not be putting out enough voltage to charge the trailer battery. The output of the alternator is usually determined by the voltage level at the TV dash. Wire size and distance to the trailer further reduce the voltage. A #10 wire from the TV battery to the trailer plug will significantly reduce voltage drop. Turing on your headlights may also up the system voltage (watch the voltmeter on the dash to see if this has an effect). Are you leaving the TV engine running and the trailer plugged in while you lower the landing gear?

Your TV will charge the battery no matter how well its own battery is charged. You can think of it as the camper battery "taking" the current it needs and not so much that the TV is just putting it out.
Check the voltage at the camper battery while it's running. It should be very close to the TV voltage. If it's a bit low, maybe 1V less, then you should see the voltage steadily rise. If not then you aren't charging. Ford has a fuse for the output so if it's not working then that would be the first thing to check.

First, Ford often ships new trucks with the relay for the trailer charge circuit not installed. On the two I owned and more I test drove, they were in a plastic bag in the glove box or behind/under rear seat. Consult your owners manual for the location of where it goes and verify in your distribution box. For a check on that, as All I could afford said, truck running in park, check voltage at RV battery when connected to 7-pin is higher than when truck off. Etrailer has good diagrams, vehicle side outside, RV style.

Besides that, in 2 hours you may have depleted your RV battery running the fridge off an inverter. You should do a power analysis on your RV. I too recommend using fridge on propane instead of inverter.

Just measure DC voltage at your rig's battery when you're attached to your truck and truck is running. Should see 13.2 or better if voltage is actually reaching your RV battery, and if it is it's still not delivering the amount of amperage being consumed by your inverter while powering your fridge. Not worth the hassle of running thicker wire when propane option on fridge is functional.

I did the same thing and ran our fridge via inverter a couple times while traveling down the road and discovered that my battery was down although I was receiving a charge via alternator. Since we camp off the power grid most times getting to your campsite with depleted batteries is the wrong way to start a camping trip where shorepower is unavailable. We set our fridge to auto.

If Im not mistaken... the only time the TV will charge the camper is if the -optional- 12v wire is connected in the wiring harness. I believe its #4. Its thicker than the other light wires. In my factory plug it was NOT connected. The wiring was there, but it stopped near the battery and there was no fuse in the holder.

**As an aside, your TV is not gonna give it a good charge, the wire is too thin to really give a charge. It will offset the use of the landing legs, and the fridge running on propane, but your looking at 3-5 amps max.

BTW, the fridge will run cooler on propane than on electric.