Towing vehicle battery voltage drops to 10 volts overnight with camper RV plug attached and NOW shore power hookup

[Heckler45]

GOOD morning fellow rv owners. We have had two travel trailers in the past 20 years. This is our FIRST travel trailer with a 12 volt refrigerator/freezer system and a solar panel. I worked as an automotive technician for 32 years so I maintain all of my equipment like you wouldn't believe. We picked up our camper from the rv dealership (Refrigerator cooling issue) on Friday and I just left it parked in the driveway hooked up. I left the 7 pin rv plug attached and DID NOT hook up any shore power. I went to move the truck the next morning and the battery was low, I could tell by the sound it was making and thought "This isn't good." I checked the truck 12 volt battery and had 10 volts. My first thought was, of course the battery...but it's only 3 years old. I charged it overnight and it passed with flying colors. Then, I checked the alternator output....oh yeah, 100 amps and room to spare. Time to move on to a voltage/current draw.........I used my trusty Fluke 77 meter and nope, NO current draw other than the typical parasitic draw. I then remembered that the 7 pin rv vehicle plug has a 12 volt tab.......could the camper be drawing the vehicle battery down a few volts? So, I disconnected the shore power cord and backed up the truck to the camper. I had my wife watch the Fluke meter reading as I re-attached the 7 pin rv cord from the camper. There it is, the current draw increased to 1 amp. Has anyone else had this issue? We never had this issue with our last two campers.

 

[Kevin D Pem]

Did you install a battery isolator in the truck?

What amp capacity are the trailer battery bank.

Did the batteries have the same reading (voltage) in the trailer as the trucks?

As simple as wiring really is. The complications land in the calculations.

Most people expect to much from batteries, and the related charging system.

 

[Heckler45]

I never needed to install a battery isolator in any of my towing vehicles before. I still have my 1994 Chevy Suburban I used for towing the last two campers, never an issue. The camper has only one 12 volt battery now, I am installing two in the near future. I did not check the voltage of the camper battery vs the truck battery. I purchased the 2012 Dodge Ram brand new so I know the entire history of the truck. NEVER had any electrical problems before. One way I guess to really perform a quick diagnosis is to hook up the truck to the camper with the 7 pin rv plug, disconnect the shore power cord and then.....shut off the refrigerator. If the truck battery maintains 12 volts and starts right up, there's the answer. My main concern is has anybody else had this issue with the newer 12 volt refrigerator/freezer design?

Did you install a battery isolator in the truck?

What amp capacity are the trailer battery bank.

Did the batteries have the same reading (voltage) in the trailer as the trucks?

As simple as wiring really is. The complications land in the calculations.

Most people expect to much from batteries, and the related charging system.

Thanks for the response.

 

[Phillbo]

I would never leave mine plugged in to the truck overnight. Not worth killing the TV battery and leaving me stranded in the morning.