trailer hitch power

[Left Coast Geek]

I just got one of those trailer 7-blade testers that has like 6 LEDs. The '12V power' LED never seems to light. My trailer has that wired to a Victron OrionTR 12/18 (12V 18A) DC-DC charge regulator because my last truck didn't output enough voltage to charge my trailer's Lithium batteries. in fact, at 14V 18A, the voltage at the Orion (in the back of my trailer) was down around 10V. Edit: I turned that Orion off with the previous truck, and am using solar as my primary charging. With my Expedition, I tried to get into the Orion to reenable it and its acting like its not powered at all, hence my testing the 12V circuit at the 7-blade.

I'm *guessing* this has something to do with the Expeditions' smart trailer detection...

edit: oh, I have a 2019 Expedition Limited Stealth, with the HD tow option. My trailer, a 21' Escape fiberglass, has been upgraded to 412AH (5260 WH) of Lithium-Iron-Phosphate, with a Lithium compatible power center/converter, said OrionTR DC-DC (thats disabled), and a Victron SmartSolar SMTP 100/30 solar controller driven by a 360W solar panel. I can dry camp for a full week with the solar turned off, and 1.5-2 days of sunshine will return it to 100%.

 

[Meeker]

There's a thread on this somewhere (or it was mentioned in a thread) - in short, the alternator is "smart" and only puts out charging voltage when it needs to - often times it is not charging at all because it thinks the truck battery doesn't need it. When I talked to a guy at the RV store about my solar system he mentioned that they don't rely at all on vehicle charging anymore because of this. Gone are the days the truck would top up the trailer battery while you drove.
I can still see a few amps going to my system when driving (at times) but not all the time. The solar panel actually does most of the charging even when driving.
It is also possible (never confirmed this) that you have to trick the trailer connector box into thinking there's a trailer attached before it enables the 12V.