I was under the impression from somewhere that the RV house battery(ies) would be charged from the TV while driving with the umbilical attached. However on a recent trip we had stopped overnight in a K Mart parking lot and used some small portion of the charge running out the bedroom slide and some fans, while also charging some phones and an iPad. When we got home, I was a little surprised to find I had barely enough battery to run one slide out for unloading. House batteries had not charged at all in about four hours of interstate driving. Do I have a problem or a misconception?

Ford requires a relay and a fuse to be plugged in to activate the 12 volt to the trailer. They came in a plastic bag when the truck was bought. Check if these have been installed in your F350.

I am in the same boat. Looked to see if dummy fuse had a real fuse and it did. Mine is a gm. Not sure if my camper is even wired to charge from tv.

I have a 12 Silverado and it charges my trailer while towing for sure.

In a related situation with my 2010 motorhome it seems that when running down the road only the engine battery gets charged and then vice versa when plugged in at the campground just the house battery gets charged and not the engine battery. Why dont they wire them to charge both from either source?

charging while driving | Good Sam Community

6dot6
Explorer
Aug 16, 2013
Got it figured out. Was a fuse. . I unplugged my trailer battery and my tongue jack still works off my trucks pigtail now. Which is awesome. Dont have to worry bout pulling it out of storage with a dead battery.
Old-Biscuit
Explorer III
Aug 16, 2013
6dot6 wrote:
So far as a test i unhooked battery and plugged 7 pin in truck. Theoretically i should be able to use the electric tongue jack with just the truck plugged in right? Ill check for power at 1oclock but thought that 1 was running lights? I gotta look again.

NO.with battery disconnected you would have no power to tongue jack.
Power from tongue jack comes directly from trailer battery.

Charging power from truck goes to trailer battery.

Blade type 7 pin receptacle (on truck)

Round pin type 7 pin receptacle (on truck)

12V Power from truck to trailer battery is at 1:00 position when you open cover on truck receptacle......most covers have a diagram on them.
campigloo
Explorer
Aug 16, 2013
Is your battery good?
oldtrojan66
Explorer
Aug 16, 2013
Thanks for the help and advice. You folks are the greatest!
down_home
Explorer II
Aug 16, 2013
Our Ford Dualies had a twenty amp breaker and a seperate fuse under the hood. It came with spare fuses and a puller in a bx under the hood. It didn't contain the twenty amp fuse though.
The repair place had tried to raise the fifth wheel, with a near dead batteries and connected it to the truck. It blew the fuse.
The truck does charge the batteries. Our 05 had two big alternators to handle that and other chores.
I had to go to a truck and trailers place to get a heavy duty connector when it was wired up for towing. Rather I didn't have to but I did. The wimpy little thing a CW and little connectors or crimps that bite through the wire was a no for me. Heavy wire and solder and so on. Twenty amps at a connector that might see moisture going down the road.
:)
6dot6
Explorer
Aug 16, 2013
Ok so tested and found no power. Checked fuse and it was popped. Was certain i checked that first. Ohwell ill replace tomorrow and see if she charges.
6dot6
Explorer
Aug 16, 2013
So far as a test i unhooked battery and plugged 7 pin in truck. Theoretically i should be able to use the electric tongue jack with just the truck plugged in right? Ill check for power at 1oclock but thought that 1 was running lights? I gotta look again.
Old-Biscuit
Explorer III
Aug 16, 2013
Turn truck ON (some trucks pin is hot w/o ignition on)
Open cover for umbilical cord
Check for 12V DC between the pin at 1:00 position and a good ground

NO 12V....then fuse/relay in truck is bad or not installed
YES 12V...check trailer for an in-line fuse/circuit breaker that is blown or needs reset on charge line.

When you have the proper fuse/relay and charge line is connected to that fuse/relay you can charge/maintain battery in trailer......not going to charge a low battery as the charge line is not very large.
timjcarter9
Explorer
Aug 16, 2013
Sea'scape wrote:
Ford requires a relay and a fuse to be plugged in to activate the 12 volt to the trailer. They came in a plastic bag when the truck was bought. Check if these have been installed in your F350.

Same with GM. In the under hood fuse block.
samandtheduck
Explorer
Aug 16, 2013
I had the same problem. I couldn't get into my site a day early and had to park in overflow and battery wasn't fully charged after a five hour drive. I used a 12v tester to check the 12v output on the 7 pin connector on the truck and it was good. I traced the wire from my umbilical cord to my trailer fuse panel. Just before it went into the panel there was a pigtail fuse holder with a blown 30 amp fuse in it. Replaced the fuse and it charged the trailer batteries from the truck.
Brian