Dedicated 10 ga wire for power to 7-pin on TV

[Doug & Betty]

I have seen several mentions of running a dedicated 10ga wire to the 12v pin on the 7-pin jack on the TV but what is the best or preferred source for this power at the front end? Direct to the battery seems the obvious choice but would the voltage regulator or someplace else be better? Also, what fuse amperage would be recommended for this wire? This in anticipation of needing it to run the fridge on 12v whilst underway. Thanks.

[Santiago]

Hi Doug and Betty, if your 3 way fridge uses 15 amps when on DC as I have read here, I would use a much bigger charge wire from your battery to the tow vehicle bumper connection. On some vehicles such as my Ram 1500, the connection stays ON after you turn engine off. This will drain your vehicle's starting battery in short order. There are remedies for this as well.

[Brian B-P]

Originally Posted by Doug & Betty

I have seen several mentions of running a dedicated 10ga wire to the 12v pin on the 7-pin jack on the TV but what is the best or preferred source for this power at the front end? Direct to the battery seems the obvious choice but would the voltage regulator or someplace else be better?

Direct to the battery has two problems:

1. there needs to be an overcurrent protection device (fuse or circuit breaker)
2. running down the battery...

   Originally Posted by Santiago

   On some vehicles such as my Ram 1500, the connection stays ON after you turn engine off. This will drain your vehicle's starting battery in short order. There are remedies for this as well.

The remedies are devices such as a relay (controlled by the vehicle's ignition switch) which shuts off the power when the engine is not running. A competently designed factory-installed towing wiring package which includes a trailer battery charge circuit would not leave the power on without the engine running; however, no wiring package with the charge circuit was available for my van.

But yes, the charging circuit doesn't need to run through anything other than a fuse or circuit breaker and a relay or similar device. I used 10 gauge wire and a 30-amp circuit breaker and a relay which is only on when I leave an underhood switch on (I leave it on for the whole trip, but off otherwise) and the engine is running. If I had to do it again, I would consider an 8-gauge wire.

Originally Posted by Doug & Betty

Also, what fuse amperage would be recommended for this wire? This in anticipation of needing it to run the fridge on 12v whilst underway.

The fuse needs to be rated at less than the safe current-carrying capacity of the wire. Details vary by wire insulation type and installation details, but typically a 30-amp fuse (or circuit breaker) is used with 10 gauge wire.

[Ron in BC]

Originally Posted by Brian B-P

But yes, the charging circuit doesn't need to run through anything other than a fuse or circuit breaker and a relay or similar device. I used 10 gauge wire and a 30-amp circuit breaker and a relay which is only on when I leave an underhood switch on (I leave it on for the whole trip, but off otherwise) and the engine is running.

I have 10 ga. wiring, a manual switch and a 30 amp fuse. I only use it when conditions aren't good for solar and my battery isn't fully charged. Since I only turn it on once in a while for a specific purpose I've never had any problem remembering to turn it off when I'm finished driving for the day.

Ron

[Brian B-P]

Originally Posted by Ron in BC

I have 10 ga. wiring, a manual switch and a 30 amp fuse. I only use it when conditions aren't good for solar and my battery isn't fully charged. Since I only turn it on once in a while for a specific purpose I've never had any problem remembering to turn it off when I'm finished driving for the day.

Ron

Good, but I think most people would prefer that the system is functional every time the trailer is plugged in - I certainly do.

Anyway, the manual switch qualifies as something like a relay - it provides a method of controlling the connection between the tug and trailer batteries. Having to unplug the trailer cable whenever the engine is shut off wouldn't be acceptable to me (although apparently it is to Fiat Chrysler), but the manual switch is a lot better than that.

[Santiago]

Originally Posted by Brian B-P

But yes, the charging circuit doesn't need to run through anything other than a fuse or circuit breaker and a relay or similar device. I used 10 gauge wire and a 30-amp circuit breaker and a relay which is only on when I leave an underhood switch on (I leave it on for the whole trip, but off otherwise) and the engine is running. If I had to do it again, I would consider an 8-gauge wire.

Brian,

My charge set up is similar but designed for 40 amp feed to trailer's DC to DC charger.

In the engine compartment, I ran AWG4 from the positive starter battery terminal to a 60 amp fuse inches away in order to protect what will be a 40 amp flow.

It then goes to a continuous duty solenoid controlled by truck ignition source. As you know, when the engine is not running, without the solenoid ( in some vehicles not all ) the connection between the vehicle starting battery and trailer battery remains intact. This will almost always cause vehicle battery to go flat. Solenoid breaks that connection.

Took it one step further. Using a green lighted toggle switch, lit when on, I added to lower dashboard area. This switch cuts power to the solenoid when ignition is on while driving around at home. Call me paranoid but if I am using truck at home and not towing, I hate knowing that the solenoid is needlessly ON. It is heavy duty designed to operate continuously but I rather give it a rest until next time we tow our trailer.

As a matter of interest, my 2016 21ft is factory wired with AWG8 from hitch to trailer battery. This charge line is really charging the battery, the propane fridge taps that same battery. I think some people have the impression that the tug charge line goes directly to the fridge, No. I by passed that little wire and ran AWG4 to the trailer battery. My case is different as I have a 40 amp DC to DC 3 stage charger but all the principles mentioned here apply to smaller charge wires.

While AWG10 from tug starter battery to bumper hitch will work, like insulation and money, the more the better. As you well know, voltage drop is the enemy here. There is so little potential driving this ( tug battery to trailer battery ) that every little drop in voltage is detrimental to the "cause". If you ( or wife if you are so lucky ) has to run wiring under tow vehicle, it costs no extra effort to run heavier wire. By the way, the overall wire length is a lot more than meets the eye due to all the snaking needed to get from back bumper to engine compartment. Longer length = more voltage drop.

[Santiago]

Last two views.

This shows the truck cabin switch. It's mounted in an oval shaped backer I made from ABS sheet and riveted in place. Wife ( Kim ) painted the white ABS backer black.

[Tin]

Very Nice job looks great!

[Ron in BC]

Originally Posted by Brian B-P

Good, but I think most people would prefer that the system is functional every time the trailer is plugged in - I certainly do.

Anyway, the manual switch qualifies as something like a relay - it provides a method of controlling the connection between the tug and trailer batteries. Having to unplug the trailer cable whenever the engine is shut off wouldn't be acceptable to me (although apparently it is to Fiat Chrysler), but the manual switch is a lot better than that.

If I ran the fridge on 12 volts or hadn't just driven across Canada and the US without ever having to use that source of power I'd probably think that a remote or automatic function was more important. But solar did the job, sunny days or not and I'm not likely to ever run the fridge on 12 volts.

Ron

[Doug & Betty]

Thank you all for the great tips! 8ga it will be. I like Santiago's solenoid and separate switch. I was concerned about battery drain but had not thought of an inline solenoid active only when the vehicle is running. That's why I came to the forum.

Santiago, thanks also for the photos. Would you please let me know what solenoid you used. I can see some of the data in the photo but not all of it.

I've towed over 25 years without any issues of the fridge not working on propane while underway but it sounds like the newer units might have this problem. Running this dedicated power wire is easy insurance should it be needed. The DW is a great assistant with tools and such but I will be the person crawling around under the TV.

Doug

[Santiago]

Originally Posted by Doug & Betty

Would you please let me know what solenoid you used. I can see some of the data in the photo but not all of it.

Hi Doug, glad it helped.
Please know that I tend to overdo things so adjust your project to taste.
My setup is for house battery charging while driving as I did not install solar panels.

We like touring everywhere and don't really camp unless its a great and special park. So because we drive all over, the 220 amp alternator more than keeps up. There are too many square miles to explore and locals to talk to in North America to cover before we drop dead. We do same overseas via buses and trains with one carryon backpack but North America is just as great to explore.

Good that you will match ETI's charge wire size, AWG8, costs a few dollars more but as I said labor is same. You only need to run positive. At rear of vehicle find bolt that will not undo anything if removed. Grind circle around opening to bare metal so your ground lug makes good contact, after bolting back on, cover with glob of water proof sealant.
I found an empty pre-drilled hole in my truck frame. Drilled it some more, tapped it and inserted machine bolt for my ground.

PARTDEAL.com is the place I ordered from.
Cole Hersee Solenoid 12V SPST Grounded Continous Duty - 24612-10-BX 77136716 1 $22.50

Good that DW helps, mine does too.
Unfortunately her going under the truck falls under the category called wishful thinking.