Ford trailer battery charge relay? - Page 2

rob_gendreau · 03-23-2015, 01:00 PM

I get your point. But at .2A, does it matter practically?

But having said that, I've discovered that there is a "auxiliary" power center pole in a 7-way, and on some plugs it's labeled "backup lights." On my Ford schematic they're marked as the center pole, bk-lg, for backup lights. Haven't been able to test since it seemed to want to back over me and my multimeter when I put it in reverse...

But that might be a better option, since I was trying to avoid have to run from the backup lights themselves, and since I found a 12v LED I thought of adding as supplemental light back there.

carringb · 03-23-2015, 01:22 PM

Correct. Center pole is backup lights. They also run through their own relay, so it can support many more amps than the backup light circuit in the taillights.

As far as concerns over the voltage regulator.... It's built in to the alternator (except on the newer vans) so it doesn't really care where the load is. On the older vans (pre-'05) the trailer charge relay is simply switched by the ignition, at which point the batteries are effectively paralleled. On the newer vans, it may delay connecting the aux battery if the starting battery is low, but once it reaches a minimum charge then the relay is connected full time.

E350 · 03-23-2015, 01:45 PM

Excellent carringb! Thank you very much for correcting my misstatement and concerns.

rob_gendreau · 03-23-2015, 01:51 PM

Cool. Now I have a couple of sources for power.

The backup camera isn't as effective as I thought it might be as a rearview mirror substitute; just too distorted in favor of a close up view. I have another camera I could use, but enough's enough. Just don't wanna back over any more campsite bollards....

dhally · 03-23-2015, 09:43 PM

Quote:

Originally Posted by rob_gendreau

Cool. Now I have a couple of sources for power.

The backup camera isn't as effective as I thought it might be as a rearview mirror substitute; just too distorted in favor of a close up view. I have another camera I could use, but enough's enough. Just don't wanna back over any more campsite bollards....

Our van has the backup radar and I like it, a lot! I've been in vehicles with rear cameras and I suppose one could get used to it, but the radar works even for dummies.

Another power source at the rear might be the rear AC. Our van had the rear AC and there is a 50 amp feeder in the rear wall, driver side, right next to the door. It is controlled by a relay that works with ignition. Don't know if the wire is there on a non-rear-AC van or not.

rob_gendreau · 03-24-2015, 10:43 AM

I managed to blow a fuse on the installation of the front screen after all that research and work on the rear power for the camera. Go figure.

I was wiring to an unused hot circuit that goes to the house battery in the overhead, that was preinstalled by SMB but never used by me. Guess it was for a CB or something. I had wired in a fuse and a powerpole connector for future use, and then ignored it.

I wired up a Y yoke in parallel for the wireless receiver and the LCD screen, and it blew the 5A fuse after a few minutes of use. I don't seem to have any faults in the wiring, and the LCD is fried.

I'm sort of at a loss to explain it. The LCDs are built with the ability to sense a video signal and turn on, and perhaps using a wireless transmitter somehow borked that. It would kind of stutter like it was trying to get the video. But that doesn't seem to explain a 5A short.

Guess I should double check the splices (the LCD and receiver wires are so small I thought they might blow before the 5A fuse, but glad I had the foresight to install a fuse up there.