2017 F150 7-pin Trailer Battery Charging Output

[Jammer]

Joe,

I have a 2017 F-250 now.

You are correct, you will not get 12v to the trailer until you start the truck and go through the motions of driving, and the truck electronics have to recognize the presence of a battery.

I ran into this when I had left something on in the trailer while in storage, and was trying to get the fridge going.

[hranchaz]

You have to go through a short process to get the newer Ford F-150 trucks to "recognize" the trailer so it will start charging the travel trailer's batteries. It is not plug and play. No rewiring, work-around or new fuses, required, just a couple of steps that Ford built in. Here is a short video illustrating how to do it:
https://youtu.be/8aX6HrPUnB8

[vanderwielen]

I know this is an old thread, but the issue with most of the above is the fact that the wire size on most trucks, including my Ford F150 King Ranch is only 16 gauge. The total resistance of the charging loop is .161 ohms, so with a charge current of 10 amps, you are dropping 1.61 volts which will only charge an almost depleted house battery. In my case, my Victron DC to DC converter drops to 9 volts under an 18 amp load, which is problematic. So, the only cure it to install a separate beefer feed to the rear bumper to a pair of Anderson terminals.

[Wazbro]

Originally Posted by vanderwielen

I know this is an old thread, but the issue with most of the above is the fact that the wire size on most trucks, including my Ford F150 King Ranch is only 16 gauge. The total resistance of the charging loop is .161 ohms, so with a charge current of 10 amps, you are dropping 1.61 volts which will only charge an almost depleted house battery. In my case, my Victron DC to DC converter drops to 9 volts under an 18 amp load, which is problematic. So, the only cure it to install a separate beefer feed to the rear bumper to a pair of Anderson terminals.

My Chevy has a 10 gauge wire which is the industry standard and required for the 30 amp fuse on the circuit. Unfortunately not all vehicles are wired to the industry standard.

Still kind of small to charge trailer batteries.

[pjshier]

Odd that your charge circuit is 16ga; our F250 KR is a 10ga wire on a 30 amp fused circuit. With the 18 amp DC-DC controller/isolator we are seeing respectable current flow to the AS LiFePo batteries. For us it is not THE charging approach, but one of three: TV, solar suitcase and backup generator.

[gypsydad]

Not sure about the pigtail being the issue here? I know my "new" F150 Platinum several years back, did not charge my AS; We called Ford dealer and a service tech told us they did not include the fuse for this, gave me the slot to look for it up front, and sure enough, it was empty. Friend had same issue with his F150; sure enough, his slot was empty also. There was a thread or two on this a while back.

Now, there also is a thread or two on the pigtail not staying connected to the from the AS to the Ford TV receptacle, causing "disconnected" alert for lights/brakes. AS replaced my receptacle 3 years ago, and that was fixed. But several folks have reported this issue also.

[JJTX]

Originally Posted by JoeHTP

We just picked up our new 25' FC yesterday, and are towing it with our 2017 F-150 XLT.

All the trailer lights work perfectly (running, brakes, etc.), but we cannot seem to get any battery charging voltage. As I understand it, prior to 2015, F150s required a relay to power to the charge line, but post 2015, it is a smart connector that is supposed to detect when there is a load on the connection and provide power automatically. No relay.

The trailer towing setup on the dash detects the AS, the only thing not working is the charge line.

Anyone have a clue as to how to solve this?

Ford dealer told me my 2015 even with tow package had NO charge circuit from battery to the trailer. They had to add it with a separate wire and advised this is common. On newer ones, too. So, they added the wire from the battery to the pin on the back harness.

So generally, ford does NOT power this pin factory to the F150, its not a mistake. I'm sure the reason is the constant power draw. If there is a problem with your trailer battery or your trailer drawing voltage when off or what-not, it will kill the truck battery. They added a fuse in line at the battery and it works fine now.

Just remember, if you park plugged into your trailer and theres a power draw it will kill your truck battery as well as the trailer.

[vanderwielen]

Originally Posted by JoeHTP

We just picked up our new 25' FC yesterday, and are towing it with our 2017 F-150 XLT.

All the trailer lights work perfectly (running, brakes, etc.), but we cannot seem to get any battery charging voltage. As I understand it, prior to 2015, F150s required a relay to power to the charge line, but post 2015, it is a smart connector that is supposed to detect when there is a load on the connection and provide power automatically. No relay.

The trailer towing setup on the dash detects the AS, the only thing not working is the charge line.

Anyone have a clue as to how to solve this?

You’re discovering the same issue I had. The wire in your f150 is too small, and what current you can draw is insignificant thus charging doesn’t occur. You’ll end up with a DC to DC converter with a smart alternator setting. Also, load up on solar. I get more with solar on the the road, than the DC to DC converter

[ROBERT CROSS]

Originally Posted by paiceman

We had an F150 I think it was a 2012 Ecoboost. Ours did not charge, there are two fuse boxes on the F150s. The fuse for the trailer charging, at least on ours, was up front in the engine compartment and there was no fuse in the slot. Put the proper one in, don't remember what it was, and we had charging.

Bud

Probably this...we even had a separate wire to connect to the positive buss under the hood.👍

Bob
🇺🇸

[66coupe]

As others have noted. Check yr owners manual for the fuse locatiion in the fuse box behind the radiator top of motor. In mine & every 150 i know of that fuse is stashed somewhere in the cab. Mine was in the dr door cupholder…..