Trailer drained my truck battery?

Gary44 · 09-11-2017, 10:06 AM

Apologies if this has been addressed before, but I can't search the forum on my tablet.

I left my Chevy Tahoe hooked up to my Grey Wolf 26rr while parked at my house, after a week the trailer batteries drained because I left an inverter plugged into the 12v plug. But the Tahoe battery is completely dead also. I didnt think that was possible. Can someone tell me if this is normal? If so, that would suck out in the boondocks.

**ependydad** · 09-11-2017, 10:25 AM

Yep. I actually banked on this happening one cold night in Tucson. The camper battery went dead by midnight. I plugged into the truck to have heat + CPAP overnight. Fortunately I have 2 truck batteries and I disconnected one so that I had something to start with in the morning.

If i'm ever hooked up overnight, I unplug the umbilical cord to the truck. I drape it so that it's obvious to me AND I tell my wife to remind me before I drive away.

rockfordroo · 09-11-2017, 10:37 AM

Yes, for a Chevy, it's normal. The aux power circuit is not switched (i.e., it's always on). Either pull the umbilical cord to the trailer or install a switch and/or ignition switched relay in your Chevy's aux power circuit.

I installed a relay and switch in my Silverado 1500, but I just pull the umbilical in my 2500.

NMWildcat · 09-11-2017, 10:43 AM

Some vehicles have a battery isolating solenoid that interrupts power to the trailer plug when the key is off. Some come standard, some come as part of the tow package, and others are added. You can easily check your vehicles trailer plug with a meter to find out.

Even though my truck has this solenoid, being a creature of habit, I still remove the plug when stopped for the night without unhooking.

aeblank · 09-11-2017, 10:55 AM

I installed a 12v charge controller. It disconnects the feed when the source (truck) goes below a certain voltage.

I'll forget to plug or unplug eventually......

Mountainmanbob · 09-11-2017, 02:02 PM

I kind of figured this might happen that's why we always unplug for any time-consuming stops.

M-Bob

Gary44 · 09-11-2017, 02:37 PM

Well, I guess it's good that I learned this in my driveway. Thanks, guys.

Now, I'm off to find a butcher that sells crow, because I rolled my eyes and told the wife the system doesn't work like that.

Crusadernoob · 09-11-2017, 02:47 PM

Quote:

Originally Posted by ependydad

Yep. I actually banked on this happening one cold night in Tucson. The camper battery went dead by midnight. I plugged into the truck to have heat + CPAP overnight. Fortunately I have 2 truck batteries and I disconnected one so that I had something to start with in the morning.

If i'm ever hooked up overnight, I unplug the umbilical cord to the truck. I drape it so that it's obvious to me AND I tell my wife to remind me before I drive away.

Yup, unplugged on night in Albuquerque, as always I asked the DW to remind me, needless to say we were in a hurry and drove off with no lights! Lucky for us we had planned a first thing stop at Wally World 2 miles down the road.

**Mr. Dan** · 09-11-2017, 02:48 PM

Quote:

Originally Posted by rockfordroo

Yes, for a Chevy, it's normal. The aux power circuit is not switched (i.e., it's always on). Either pull the umbilical cord to the trailer or ....

... and for a GMC, of course, since a GMC is pretty much a Chevy with a different smile and different mix of option packages.

We have crow here but you'll have to procure them yourself. I ate some a couple of years ago when I mentioned to my son (GM world class master technician) that my plug was surely dead when the truck wasn't running. He said, "Nope, test it". So I tested and logged voltage with key off, key on but not running, and truck running. All numbers were different... all were 13+ volts. Now I pull the umbilical cord even if I'm hooked to shore power.

Mountainmanbob · 09-11-2017, 06:44 PM

After running them down great time to put some distilled water in those batteries.

And then a nice full charge.

M-Bob

jjuscg · 09-11-2017, 07:34 PM

Quote:

Originally Posted by NMWildcat

Some vehicles have a battery isolating solenoid that interrupts power to the trailer plug when the key is off. Some come standard, some come as part of the tow package, and others are added. You can easily check your vehicles trailer plug with a meter to find out.
Even though my truck has this solenoid, being a creature of habit, I still remove the plug when stopped for the night without unhooking.

Don't know if it's a Chevy / Ford issue (and NOT trying to start that debate!) but my Expedition does have a solenoid that shuts off power to the trailer plug when ignition is off. I do still unplug if I stop overnight on the road without unhitching the TT,

Poper · 09-12-2017, 07:55 AM

Don't think it's chev /ford specific.
My Dodge Ram was drained in less than two weeks hooked to TT. With NO battery in TT!
Here's the glitch.
I had removed the battery from TT to take home and charge it but leaving TT and truck at my deer camp.
Neglected to unplug 7pin from TV. When I returned, the truck was stone dead....no draw whatsoever. It's an older 1995 Dodge with no bells or whistles.
My theory.......magnets of four wheel electric brakes on TT was the draw, even though brakes were not engaged, they were hooked up.
Just a thought.....
Now even when leaving overnight in my home driveway, I in plug from my other TV 2015 Silverado HD. Not taking any chances. Just got to remember to reconnect.

aeblank · 09-12-2017, 09:23 AM

Fords are the only one that I know of that cut power. Most of the time, it's probably a good thing.

How old is your deer camp trailer? Any modern-ish trailer has drains. Fridge, radio, CO detector, any other electronics. Mine will start beeping after probably 3 or 4 days. 2 weeks? Totally dead for sure.

Gary44 · 09-12-2017, 09:39 AM

Sooo...since it is a complete circuit, will it work the other way? When I plug in AC power, it should charge my truck back up, right?

rockfordroo · 09-12-2017, 09:41 AM

Quote:

Originally Posted by Poper

Don't think it's chev /ford specific.
My Dodge Ram was drained in less than two weeks hooked to TT. With NO battery in TT!
Here's the glitch.
I had removed the battery from TT to take home and charge it but leaving TT and truck at my deer camp.
Neglected to unplug 7pin from TV. When I returned, the truck was stone dead....no draw whatsoever. It's an older 1995 Dodge with no bells or whistles.
My theory.......magnets of four wheel electric brakes on TT was the draw, even though brakes were not engaged, they were hooked up.
Just a thought.....
Now even when leaving overnight in my home driveway, I in plug from my other TV 2015 Silverado HD. Not taking any chances. Just got to remember to reconnect.

Unless you had pulled the brake cable and activated the brake switch, your problem wasn't the brakes. Most likely it was the parasitic draw from such things as your CO/LP gas detector.

Poper · 09-12-2017, 10:00 AM

Hmmmm.. that does make sense.
Even with no battery installed, I guess the parasitic draw was still there from LP etc etc
TT is a 2012 so it has all the current draw items mentioned.
Thanks, makes perfect sense

aeblank · 09-12-2017, 10:24 AM

Quote:

Originally Posted by Gary44

Sooo...since it is a complete circuit, will it work the other way? When I plug in AC power, it should charge my truck back up, right?

Yes. Though slowly.

Gary44 · 09-12-2017, 08:41 PM

Well... I plugged it in to AC, and after about 4 hours, truck started right up. So, I guess I now know that if it happens again in the boondocks, I can run the Gen to charge the truck.

Mind blown.

aeblank · 09-12-2017, 09:02 PM

Wires don't care which direction the juice flows. Similar to the cigarette lighter "jumper cables".

Skyliner · 09-20-2017, 07:26 PM

When the same happened to me several camper's ago, my converter and the wiring to the truck didn't provide enough "juice" to recharge my tow vehicle's battery. I ended up unplugging the tow vehicle and the converter charged up my two trailer batteries. I then pulled one out to jump start my truck and the 250 mile drive home charged up my tow vehicle's battery easily.

I have a new tow vehicle and that isn't an issue for us anymore. Now I have to make sure that DW closes the truck door completely or the light stays on for a while draining the battery.

Since I often camp off grid in the mountains away from campgrounds, I often have a couple of backups. In addition to solar and 3 battery banks each 232 amp-hours, I have a 3000 watt inverter generator, a 800 watt 2 stroke generator, and a small 50 amp-hour automotive battery charger that I can use if my converter dies or I need to recharge a dead tow vehicle battery.

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