Set up 2015 F150 4x4 King Ranch for Towing

[GWHunter]

I am in the process of installing a Blue Ox Tow system on my F150 and looking for feedback on if it needs a Charge Line or fuse cut out switch. There are no issues with putting the truck in flat tow mode but I am finding contradictory information on the necessary wiring accessories ie charge line and brake fuse cut out switch. I am planning on installing the Blue Ox wiring harness with diodes that will drive the truck lights. Any recommendations for what is needed to set this up are appreciated. Will be towing with 2007 Millennium H3-45.

[No Name]

After 3-5 days on the tow bar without running the Jeep we find the battery dead - this doesn't happen when the jeep is disconnected from the bus. We've turned off the lights, A/C, Radio, etc.. The Jeep has 2 batteries (regular size main battery and a motorcycle sized auto start/stop battery). I don't know if this is a Jeep/battery issue or a drain while towing issue. We are using the Blue/Ox bar and harness. I too was considering using the charging circuit in the 7-pin (for trailer brake battery) - black wire on pin 4. I've read about installing a diode that is 2x the voltage and 2 x the current of what the 7-pin can output (24v and 20-30A).

I did things a little bit different thinking I may want to have some form a brake set-up and a charging set-up in the Jeep at a later date so i installed a 6-pin on the Blue-Ox tow bar (cutting off the 4-pin with the kit and connecting to the 6-pin) - I'm running the BlueOx 7-pin to 6-pin BX88206 706 Coiled Electrical Cable Extension. The 6-pin fit well onto the Blue-Ox adapter bar on the Jeep, however I had to use #10-14 threaded rod and nuts on both ends to connect the 6-pin to the existing tubes. It is a little off-set on mine as I imagine it depends on the make/model 6-pin you install.

Regardless, with the jeep battery dying like it does, I'll be getting a diode and installing on the Jeep battery side at the ring terminal/battery terminal, probably a 10 or 15A in-line fuse as well and a black wire to the 6-pin.

A reply from an "expert" stated this - I somewhat disagree as many times I've hooked up to e-brake trailers who's brakes were almost not noticeable in at the start, then after 30-60 minutes they would start locking the wheel under full brake application (thumb on manual brake application). So the battery had to be charged by the tow vehicle as the brake force improved with time/charging.

From the expert:
"The above method will do a nice job of maintaining the trailer battery charge but the 12V circuit won't provide quite enough power to actually charge the battery up during travel. If you'll actually need to charge the battery your best option will be to add a DC to DC charger like the Redarc # 331-BCDC1225D, which will boost that charge and includes an isolator to cut off power when the truck is off. "

I'm curious if anyone else has a tow vehicle discharge issue like I do - seems there is a lot of internet chatter about this exact item (charging towed vehicle from tow vehicle). I want a simple, permanent solution - the 12v trailer battery tender circuit seems the most obvious. In my application it's 5-6ft of #10 or #12 wire, a diode, ring terminal, an inline fuse/holder and some butt splices/heat shrink. ...Unless my 7-pin doesn't have a black charging wire on #4... then it gets more complicated.

I'll report back once I get this done unless you beat me to it!

[PrevostNewbie]

My 2021 Ranger 4X4 will lose battery after a long drive. I added a charge line with quick disconnects on both ends and not had a problem since.

[GWHunter]

Eddie, Mike, thanks for the feedback. I am continuing to pursue and will update the post as I find additional information.

[georgew]

My 2022 F150 would be dead after 4 hour tow added a charge line and have nort had the problem used pin 7 to the truck battery with diode on truck side

[PrevostNewbie]

George what is the diode for on the charge line?

[RichardE]

MIke

I am not sure what you are asking so I will cover the big picture. A diode is essentially an electrical check valve. It only allows current to flow in one direction. So in this case when the towed vehicle is connected it would prevent the towed battery from trying to charge the coach.

I used this diode for my charge line, and it seems to be enough. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[PrevostNewbie]

I know what a diode is and what their use cases are. A diode on the charge line is not really protecting anything except adding an additional layer of complexity.

[georgew]

George what is the diode for on the charge line?

to prevent feed back when stopped

[PrevostNewbie]

Feedback from what when you are stopped? The charge line connects a 12V source from your Bus (Battery or charger) to your Towed battery. A diode on the 12V line would be the same as a diode on the ground line. Not needed.