Can my travel trailer drain my towing vehicle's battery?

[wolfie666]

I just got a 2021 Wolf Pup 16BHS. I hired a guy to drive it to me across the country.

When it arrived from the trip (4 days), we stepped inside to fill out some forms and I just happened to notice the refrigerator was running. I opened it and the freezer and they were nice and cold. I asked the driver how it's possible it lasted this long, the refrigerator and freezer are only supposed to last about a day on the battery, according to something the dealer told me.

The driver said oh, it's probably because his truck was charging it.

I was not expecting to hear that. Does the 7-pin trailer connection... charge... the leisure battery in the trailer?

Does this mean you could accidentally drain your car's starter battery if you leave it plugged into the trailer while you use it at a dry camp site?

[Mike134]

Depends on the age of your truck. Back in the day yes it very well could. Sometime in the year 20XX truck makers started putting smart towing connectors on the trucks to stop that.

[wolfie666]

Originally Posted by Mike134

Depends on the age of your truck. Back in the day yes it very well could. Sometime in the year 20XX truck makers started putting smart towing connectors on the trucks to stop that.

Does smart mean it stops sending power when the vehicle is turned off?

I'm not sure what the shipper was driving, but me, I'm driving a cargo van with a DIY add-on 7-pin connector. I'm concerned because I distinctly remember running a conductor from a terminal on my van's starter battery all of the way to the 7-pin plug in the back. That's definitely going to drain my starter battery if I forget it connected during a dry camping trip, isn't it?

[NJKris]

Easy to determine. Turn your tow vehicle off, and check with multimeter for DC voltage on the cord's power terminal. Easy to Google 7 pin connector sketch and what each terminal does. I never did, because I unplug from tow vehicle anytime I'm not towing. Just in case.

[bikendan]

Originally Posted by wolfie666

Does smart mean it stops sending power when the vehicle is turned off?



I'm not sure what the shipper was driving, but me, I'm driving a cargo van with a DIY add-on 7-pin connector. I'm concerned because I distinctly remember running a conductor from a terminal on my van's starter battery all of the way to the 7-pin plug in the back. That's definitely going to drain my starter battery if I forget it connected during a dry camping trip, isn't it?

Does this mean your van does not have the factory tow package?
If not, you need a brake controller installed to operate the trailer brakes.
And you need to check your DIY 7-pin umbilical plug to see if the charging wire is working.

[wolfie666]

Originally Posted by bikendan

Does this mean your van does not have the factory tow package?
If not, you need a brake controller installed to operate the trailer brakes.

Yes. Thanks. I did also install an aftermarket brake controller while I was installing that 7-pin connector.

[formerFR]

or just unplug it when parked....

[CHICKDOE]

what type of refrigerator? if an absorption refrigerator running on propane it would take very little battery power which could easily be replaced via the 7-pin cable.

put a switch or ignition activated relay on your 12 volt charge line that disconnects the charge line when the ignition is not running. then it will not draw down the tow vehicle batteries when the engine is not running and the alternator is not recharging the tow vehicle battery.

[Chuck_S]

Any number of ways the refrigerator could be cold depending on the unit. Mine runs on LP or AC current and if set to AUTO will AUTOmatically switch to propane when the AC current is cut off. A 12v refrigerator is designed to run connected to the tow vehicle -- it won't last on just the battery for more than a few hour -- so that's an easy explanation as 12v Trailer Battery charge line is literally standard with all HD tow options that include the 7 pin connector. My Fords for the past 20 years have all rear connectors relay controlled and only active with the ignition. Brand X may leave that line hot which will kill the vehicle battery.

-- Chuck

[rsdata]

always disconnect the 7 pin plug when camping...

ONE BIG question... do you have a 12VDC ONLY fridge or an LP/120VAC fridge?

Look for the fridge manual in your stuff OR find the model number of the fridge and google it to find out if it is 12VDC or absorption style which uses LP gas...

[TitanMike]

Originally Posted by rsdata

always disconnect the 7 pin plug when camping...

ONE BIG question... do you have a 12VDC ONLY fridge or an LP/120VAC fridge?

Look for the fridge manual in your stuff OR find the model number of the fridge and google it to find out if it is 12VDC or absorption style which uses LP gas...

I don't disagree with unplugging if person doesn't know if 7-pin charge terminal is hot or not when engine off.

Better to test the terminal and know.

On my truck it is dead when engine is not running and this is accomplished through a simple, inespensive relay.

Only time I disconnect is when I unhitch in a campsite. Pulling the plug when just stopping could lead to one forgetting to plug back in when resuming the drive.

If I had a truck with an continuously live charge line, either due to factory installing it that way or an add-on by shop/owner, I would install a relay so unplugging was unnecessary and less chance of heading down the road with no lights or brakes on trailer.

But that is just my view.

[Reverse_snowbird]

Originally Posted by rsdata

always disconnect the 7 pin plug when camping...

Definitely unplug when camping. Don't ask me how, but a friend didn't do that when he plugged into the campsite, he got feedback into the truck that took out the electronics... very expensive repair.

As to the refrigerator, you've gotten some good advice about how to check to see if it will drain the battery. There are too many unknowns to say yes or no.

[hybridlife]

Are you sure you have a 3 way fridge on this model? I think the dealer (surprise) might not have given you the correct info. If you have a 3 way fridge (12v, gas, electric) then yes about a day would be the max for try to run your fridge on battery. If it's a 2 way fridge (gas or electric) then as stated in an earlier post it takes very little battery to actual assist with running the fridge because it is really being run on propane. In my experience I've been able to run the fridge on propane (starting with a fully charged battery) for at least 4-5 days before needing to charge up.

M

[Mike134]

Originally Posted by wolfie666

Does smart mean it stops sending power when the vehicle is turned off?YES

I'm not sure what the shipper was driving, but me, I'm driving a cargo van with a DIY add-on 7-pin connector. I'm concerned because I distinctly remember running a conductor from a terminal on my van's starter battery all of the way to the 7-pin plug in the back. That's definitely going to drain my starter battery if I forget it connected during a dry camping trip, isn't it?YES it will given enough time and the amount of load running it down.

See answers in red above

Safe travels

[bikendan]

Originally Posted by wolfie666

Yes. Thanks. I did also install an aftermarket brake controller while I was installing that 7-pin connector.

If you Google the 7-pin connector configuration pic, it will identify which pin is the charging pin.
That is if you did the DIY installation correctly.

[rekaj321]

No but when stored older models had a small trickle of power to trailer battry lowering so it then put a draw on tow vehicle and in some cases blowing tow vehicle fuses etc.. Forest R iver said this wouldn't happen but then installed a power shutoff switch in 2021 models. I have a Wolf Pup and mine is located by fuse box. When I store mine I turn key off and remove it. This eliminates ALL power drain in trailer. Like that little red light at stereo even though system is off etc. Wasn't a big drain but over time could drop your trailer battery significantly.