Draining the batteries

[diver57]

Hi
I have a 2016 GMC 1 ton dually with a 10’ 2 northern lite camper .
When I bought it I had the 7 way plug put into the box for power to the camper.
I also have 2 - 100 watt solar panels with a 2000watt inverter.
The problem is if the truck sits for 3 or 4 days it drains my truck batteries completely, and my camper batteries are fully charged
I would have thought there would have been a battery isolator in the truck somewhere.
Any ideas of what is happening here

Thanks
Sent from my iPad

[woodhog]

You could buy a clip on amp meter, put it on the truck battery
lead, shut the truck down in the normal manner, unplug the camper from the truck.
Note the reading on the meter, it should be near zero, if it is reading something on the meter, start to remove fuses in the truck to see where the parasitic current drain is taking place..

If the truck comes up clean (nothing using energy from the batteries), plug in the camper and note the reading, do the same thing to isolate
items of energy consumption in the camper that are normally off, unless turned on..

[DWeikert]

The fact your camper batteries are fully charged implies the batteries are isolated. Either you have an isolator or the wire connecting the truck's 12v to the trailer harness was never connected, or the fuse protecting that lead isn't inserted. The truck's electronics are "supposed" to go into a sleep mode and draw minimal power shortly after shutdown. Sometimes this doesn't happen. Some things I've found on my truck, I have a BlueTooth reader for the ODBII port. If I leave that plugged in with the truck off it'll drain the batteries. My guess is its activity is preventing the truck's electronics from going into sleep mode. Some insurance companies have you plug a module into the ODBII port to monitor your driving, I wonder if that could cause similar issues, if you have one. Also, the dual 12v outlets on the dash are not switched. Anything you plug into there will continue drawing current with the ignition switch off. Is there perhaps anything plugged in there when you use the camper that isn't normally plugged in? GPS, backup camera, etc.

[Marcela]

My 2017 GMC does the same thing. Install a battery isolator. Some trucks have one from the factory, some don't.....

[Eric_Lisa]

Photomike wrote:

Cannot see the camper draining the truck either. I also would say unplug truck and camper and let it sit and see what happens. Could be a huge phantom draw in the truck.

+1 It doesn't make sense for the camper to drain the truck without also draining the camper battery.

I had a problem where my truck battery was going dead. Camper was fine though. Took me a long time to find it. I had to put an ammeter in-line between the battery and power cable. I slowly went through each fuse one at a time to try and find the phantom draw. Have to be careful not to turn anything on as the ammeter could only handle a small draw without blowing its protection fuse.

Eventually found the MSD ignition box I added at one time was the culprit. I had accidentally pinched a wire when mounting the box. It had rubbed through the insulation just enough that it created a weak draw and would drain the battery after a week or two.

HTH,
-Eric

[Grit_dog]

Be more specific. What is running in the camper when it sits and drains the truck. Just the fridge?
Doesn't make sense as it "should" drain all the batteries equally. 12V from truck goes to camper batteries. Camper batteries go to the fuse panel.
What your describing is the truck is wired directly to the camper fuse panel somehow and bypassing the camper batteries.
How long does it take to drain the camper batteries, NOT plugged into the truck using the same loads?

[towpro]

My truck sits weeks at a time with no problem. Most times I just leave it plugged into camper and let my solar charge truck. Both truck and camper are AGM batteries so solar is not doing any damage to truck batteries

[AnEv942]

Typically GMC/Chevy does not have a battery isolator- charge line always hot.
Camper plugged in it will drain truck.
That said, the campers batteries showing charged not sure-

"Mechanic' should be able to check parasitic drain of truck if excessive (though should have been able to load test a battery?).

Pull the fuse in the engine bay fuse box for the trailer battery charge line if you cant easily get to camper plug. If you have manual should identify, #2 "I think" but verify.

IF somehow and kinda of a stretch, camper is disconnected from its batteries,
but plugged into truck it might use truck for power.
More questions than answers

[diver57]

I guess I should have said it drained the new batteries also

[mbloof]

200W of solar I can't imagine that the batteries would be anything but charged. 🙂

Maybe it was faulty truck batteries after all?

My old 97 would drain the battery camper or not. I installed a knife switch on the battery which got used every time I wanted to use the truck.

[diver57]

I just install two new batteries the mechanic thought maybe bad cell so replaced

[ticki2]

Check the specific gravity in the truck batteries . A bad cell in one of the batteries will do that . On GM' s you need to install the 40a fuse for the charge line to camper , is it installed ? Have the truck batteries behaved properly in the past ? An isolated or continuous duty solenoid would be a good idea .

[Photomike]

mikakuja wrote:
Interesting problem.... Have you tried unplugging the camper from the truck to see if the issue is in fact caused by the camper??
It doesn't make sense to me that the camper batteries are remaining fully charged and the truck is dead unless there is a wiring issue.
If there is ignition relay that shuts the power off to the 7 pin connector there would only be one way I could imagine the camper draining the truck batteries without draining the camper batteries... Is there is a battery switch somewhere in the camper that is wired to allow the camper to use only the trucks power while the camper batteries are shut off??
If there is constant power to the 7 pin connector (with no ignition relay) the camper should draw from both systems and the 200 watts of solar should be more than enough to keep everything charged.

Cannot see the camper draining the truck either. I also would say unplug truck and camper and let it sit and see what happens. Could be a huge phantom draw in the truck.

[mikakuja]

Interesting problem.... Have you tried unplugging the camper from the truck to see if the issue is in fact caused by the camper??
It doesn't make sense to me that the camper batteries are remaining fully charged and the truck is dead unless there is a wiring issue.
If there is no ignition relay that shuts the power off to the 7 pin connector there would only be one way I could imagine the camper draining the truck batteries without draining the camper batteries... Is there is a battery switch somewhere in the camper that is wired to allow the camper to use only the trucks power while the camper batteries are shut off??
If there is constant power to the 7 pin connector (with no ignition relay) the camper should draw from both systems and the 200 watts of solar should be more than enough to keep everything charged.

[Notakwanon]

There was no isolator in either my 2006 GMC truck or my Outfitter camper, and yes, if the truck sat for over a week it didn't want to start. I had an isolator installed, which solved this problem. Tom McCloud