Need the solar/power pros to weigh in

luthj

Engineer In Residence

TantoTrailers

Active member
I can’t seem to find the rating in the manual for the 2016 F150. The fuses for trailer lights and brakes range from 20A to 30A if that means anything. I may be able to see the wire size on the cables tomorrow but I think they are in wire housing and dirty af. Assuming it’s 10 Amp, how can I tell if it’s ignition switched?

edit: in my search I came across this thread which may apply to my truck since my 12v may shut off when I open my doors, I don’t have push button ignition so the key thing won’t apply. Still have no idea what the wiring is rated for but I’m assuming it’s ignition switched if it may shut off when opening the driver door.

 
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dreadlocks

Well-known member
A multimeter or test light on trailer plug with key in your pocket will check if its always hot or not.

BMV will show you how many amps you get when your hooked up w/engine running.. I only got about ~5A outta my vehicle plug.. brakes and stuff are own circuit, and rated for higher amps than the aux circuit usually.
 

luthj

Engineer In Residence
These DC-DC converters are just dumb converters. They will attempt to output a voltage. If that limit is exceeded they may cycle on-off for a bit. You may need to adjust the units voltage down some to prevent rapid cycling on a bank that wants to pull more than the 100W or so.
 

TantoTrailers

Active member
My life seems like a circus act of jumping through hoops! I think my truck may be in a window of poor production where they didn't wire up the charge pin with the proper wiring size...if I am not mistaken, the wiring to the 7pin is 18#...


 

TantoTrailers

Active member
So I read every comment on that video and I think I may have the wrong understanding. It seems like the guy in the video wired a new relay, fuse, and 12# cables to the 7pin connector and then went directly to the trailer/house battery. I do not think he is using a DC/DC converter. Am I correct? Would that then result in 2 ways to wire this?

1) leaving stock 18# wiring and using a DC/DC converter to get a bit more juice

2) running new wire, fuse + relay mod, and then direct to house battery (through BMV)

or is there a 3rd option where I run new 12# wire, fuse/relay mod, AND DC/DC converter?

Personally #1 seems easiest and all the modification really happens at the trailer...but this may be getting too far into the specifics of my year model F150?
 

luthj

Engineer In Residence
What is your alternator voltage? Then work out the voltage drop at something around 10A. With such a long run, you are unlikely to get more than 1-2A with the alternator running under 14V.
 

TantoTrailers

Active member
What is your alternator voltage? Then work out the voltage drop at something around 10A. With such a long run, you are unlikely to get more than 1-2A with the alternator running under 14V.
You mean running with option #2? I'm curious how the guys in the video comments were able to get up to 20A from that mod.

"I also decided to purchase SAE J1128 - # 8 gauge to go from the battery, through the 20 amp breaker, the heavy duty 12v 100A relay and to the back bumper. the entire run is wire loomed and fished through the truck frame (the passenger side is shorter FYI) . I managed to get five cable ties on the wire loom through the side holes along the frame so it's just not bouncing around inside the frame. I don't know if I mentioned this but I'm not charging a battery. I am powering 234 watts / 19.5 amps worth of LED lighting on my back bumper and boat trailer (I get there in the dark, flip the switch and it's like daytime at the boat ramp). My older F150 has this setup and it runs great on the factory harness but I didn't want to harm the harness on the new 2016 F150 with the small OEM harness wire size. Had it not been for this video... I'd might still be searching for a solution."
 

luthj

Engineer In Residence
Charging a battery is not the same as driving a load. A load will work find at 11.5V or 14V. A batteries charge rate is determined mostly by the voltage at its terminals. At 12.5V no charging is occurring, at 14.4V the battery will accept C/5 at high levels of discharge, and taper to about C/20 for the last 5% of capacity.

So the battery charge rate is a combination of alternator voltage, drop in the wiring, and battery SOC. Using a DC-DC you have more control over the batteries terminal/charge voltage.
 

TantoTrailers

Active member
I gotcha, given the facts about my truck wiring, do you think I need to do both the relay/wiring mod + the DC/DC converter or should I try going with the stock wiring as is?
 

TantoTrailers

Active member
=) simply to charge the battery while driving the truck with trailer connected. 5A-10A charge would be just fine to compensate for the power consumed by my fridge during that time.
 
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