View Full Version : Our RV Killed the truck

05-06-2019, 09:47 AM
last September I parked the truck and trailer at our storage place. A week ago I went and got the truck to haul firewood. In order to unhook I had to use the jacks and turn on the 12volt. I returned the truck, hooked up and left.

On Saturday I went to get my torque wrench from the truck. The truck would not unlock with the fob, turns out the batters were dead.

Well, I got the batteries charged and checked to see if anything was left turned on or plugged in that would drain the batteries. Nothing, then I noticed that the trailer was plugged into the truck, no big deal. I opened
the storage and checked the master switch on the trailer, it was on.
I have to believe that there is something in the trailer drawing power that killed the truck.

Does anyone have any ideas?
Remember, the truck was parked with the trailer and the trailer was plugged into the truck since September only difference is the master on the trailer was turned off. Truck started great when I went to get it to haul wood.

05-06-2019, 01:07 PM
The LP detector is always on if the battery is connected. Same for any radio/clock that is wired to the 12V system with a digital display. Were any lights left on inside the trailer, like in a closet or compartment?

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05-06-2019, 02:32 PM
There is power to the fridge and hot water tank all the time

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05-06-2019, 02:40 PM
The trailer battery charging circuit on the truck SHOULD only be live when the truck motor is running. I know that on motorized RV's they have a battery isolator component (the old ones were relays energized by the ignition being ON - the new ones are diode assemblies) that prevents the "House" (RV) batteries from discharging the motor starting batteries, so you don't get stuck at some remote campsite.

05-06-2019, 04:50 PM
You did well to have left the truck for six months and still get it to fire up. A lot of the newer trucks will draw down a battery in storage through phantom power draw thru onboard electrical (Clocks, computers, etc.) Your battery may have lost enough power during storage that it may not have had enough "juice" to start your truck and fully recharge the battery(s). Cold weather doesn't help either. I store my truck with the batteries fully charged and disconnected over winter and find the power level depleted over-winter just from sitting.

05-25-2019, 09:35 PM
I've no experience with Chevy or Dodge but my understanding is that their electrical circuits allow the trailer to pull power from the tow vehicle whether its running or not. (This could have changed, don't know.) Not a good idea to leave your trailer plugged into them for too long and the vehicle not running. I do know that Ford Super Dutys have a relay that prevents the trailer from running the truck battery down when the truck is not running.