Do you disconnect the electrical plug from your car/truck when stopping for an hour or so to shop?

SLJ · November 15

I use to disconnect the 7 pin on my old tow vehicles but my current Ford tow vehicle's factory tow packaged disconnects internally when I shut off the ignition. I don't disconnect now unless it's time to unhook at the campsite. I get 5.5 amps when idling and more when driving so plenty to power my 12 volt fridge and keep the batteries topped off when towing.

donmontalvo · November 19

ChanW said:

We installed an isolation relay when we bought our Tab. It works well. Not too difficult to install if you have electrical savvy.

As noted by others, neither unplugging the 7pin, nor an isolation relay, will save your Tab battery, if you leave your 3-way fridge going on 12V for any period of time (been there, done that!)...

We used this one (West Marine carries it):

Where exactly does this get installed?

The reason I ask, I had an off grid kit in built into my Jeep and would prefer not to do anything that can interfere with it.

https://donmontalvo.com/2022/03/27/main-line-overland-lifepo4-ftw/

Cherokee · November 21

YES we do; then we put our 3-way on LP till we start again. After I start the TV we place the ref on battery. We turn the gas OFF when we are towing for safety reasons.

donmontalvo · November 22

Cherokee said:

YES we do; then we put our 3-way on LP till we start again. After I start the TV we place the ref on battery. We turn the gas OFF when we are towing for safety reasons.

I’ll have to translate your response with fresh eyes in the morning.

MuttonChops · November 22

Interesting . . .

The first thing I did on purchasing a TAB 320S
Wassss to add a Relay in my tow vehicle to disconnect the TV battery from the Trailer Battery (7-pin) when the engine was not running.

It is a shame Truck/Car manufactures have removed the Relay that older model vehicles had.

It is not difficult for a DIY-person to add a Relay to the trailer 12VDC circuit.

ColleenD2 · November 22

I agree Scott. I prefer to use the words since we aren't paying by the letter. Then everyone is speaking the same language. 6 years in and I still don't understand all the lingo or even try to.

i have to come back to this whole discussion when my brain is clear. I have no idea what most of this is talking about. I never have the fridge on battery, I vaguely remember Bob saying with a three way it depleted the battery even when the car is running. We always have the battery switch turned to on because uhhhh doesn't the brake controller need that? Maybe I've been doing it all wrong all this time. Dana our dealer said turn it on so I turn it on and turn it off when we store after a trip. We pull the 7 way if it's more than stopping to eat, we used to pull it anytime but now about one hour at most. I wonder if the solar makes up for that draw when it's sunny. Hmmm

elbolillo · November 22

neither our ‘21 Honda Pilot nor our current ‘24 Sequoia need to be disconnected from the trailer. Pull into Walmart. Put down the stabilizers. And Bob’s your uncle.

donmontalvo · November 22

MuttonChops said:

...[snip...
...[snip...
...[snip...

It is not difficult for a DIY-person to add a Relay to the trailer 12VDC circuit.

I'm trying to understand where such a relay would be installed.

I have an off grid power kit in my Jeep, and I don't want to do anything that may cause issues.\

https://donmontalvo.com/2022/03/27/main-line-overland-lifepo4-ftw/

I definitely am in the "can't be bothered" camp, insofar as not wanting to have to remember to plug/un-plug the 7-way wire at the hitch. I'll forget.

I am not an electrician, but the decision on whether to install one or not hinges on my need to protect my off grid power kit on the Jeep.

AnOldUR · November 22

I chose the easy way out and simply disconnected the charge line in the junction box behind the tub. I find that the solar panel on the roof of our T@B is enough to maintain the battery while on the road and I have a suitcase to top it off once at a dry camping location. No problems using this method with a 12V fridge running full time.

My initial concern was the different charging profiles between the LiFiPO4's in the T@B and the lead acid in our Jeep. Probably not much of a problem, but made sense at the time.

Sharon_is_SAM · November 22

@AnOldUR. I have read that the TaB lithium battery will drain into the TV battery. We will also go the route of disconnecting the +12 V 7 pin line in the junction box.

AnOldUR · November 22

I'm not sure who to credit for this picture, but it was a good aid for doing this to our 2020 320S. The "TRAILER PIGTAIL" wire is the one that I removed. It's the heavier gauge of the two black wires connected to that post.

Image: https://us.v-cdn.net/5021717/uploads/editor/hx/ivcdfo4oa5ty.jpg

edit to add that my box wasn't as neat as the one above ...

Image: https://us.v-cdn.net/5021717/uploads/editor/8t/22eqlzzoumus.jpg

ScottG · November 22

The top pic is mine, from my 2015-S. I don't think the basic wiring scheme has changed much over the years.

To add my $0.02 to this discussion, I almost never fuss with running the fridge while on the road. The box is a pretty good cooler--pre-chilled with a container of happy-hour ice, it stays sufficiently cold for several hours. YMMV depending on conditions.

So... no need to disconnect when stopped.

AnOldUR · November 22

Interesting @ScottG. It looks like they changed some of the wire gauge sizes in the (relatively) newer T@B's.

One of the "YMMV" things is that I swapped out my 3-way fridge for a 12V chest model. It draws much less than a 3-way running on 12V. Running it while on the road doesn't draw down the battery much. Also, I'm not sure what battery types you have, but my change was less about running the TV battery down than the different battery chemistry that some of us find ourselves with when upgrading our trailers to lithium.

Horigan · November 22

Our brake controller installation included fuses under the TV hood for the brake control and charging wires. When we switched to lithium, I just pulled the charging line fuse since we get enough charge from the solar panels when traveling.

Sharon_is_SAM · November 22

So there is another option @Horigan! That may be even easier to reach. We’ll see.

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Do you disconnect the electrical plug from your car/truck when stopping for an hour or so to shop?

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