Why do my truck batteries die?

Had the same issue with my Lance/Chevy. Replaced the Battery Separator in the Lance and it resolved the problem.

There's a miniscule draw causing the problem. ALso, if the camper batteries are up there in age, they themselves will draw down the truck batteries.

I have had the same problem with Outfitter Apex, GMC truck. Batteries in both are good, if the truck is parked for a week it sometimes won't start because batteries are down. If the frig is on, the camper batteries are down in a few hours. When I know the truck won't be used for a week, a trickle charger gets hooked up.

A refrigerator can draw a lot of energy. Even with solar, do you have the Outfitter 85 watt Go Power solar system, this system cannot keep up with a refrigerator, it will keep two 6v batteries charged without the refrigerator.

Check to see if your isolator is defective, your truck should be charging the TC batteries when it is running.

The comment on bad batteries discharging good batteries is a point well taken.

Keep us posted.

Owyheedog wrote:
Any ideas to throw out there?

Yes. Stop guessing and make some tests.

Get a multi-meter and check some voltages.
If you are unwilling or unable to do that, take it to a shop where they can.

First thing disconnect what you think is a fully-charged camper battery and let it rest for a couple hours, then check the voltage. If the voltage doesn't measure at least 12.6V, the battery is weak.

Another thing you can do is put a test light in between the hot wire of the trailer plug on the truck and the plug on the camper. Might also have to connect the ground. If the light lights, there is something drawing power in the camper. The light won't light if there is no complete circuits in the camper. You could perform the same test with an ammeter to determine how many Amps are being pulled by the camper when it should be "dead."

Some trucks don't shut off the camper/trailer battery charge circuit when the key is off. You have to unplug it to disconnect the circuit.

Yes, unplug the camper and test the 12V hot lead on the trucks plug in.
When the truck's ignition is off, there should be no power to that plug.
If there is, it will power the camper batteries and drain the truck.
If that lead is dead then start checking the lights pins.
Did it just start doing this? I thought all Dodges cut power to the 12V lead with the key off.

My Chevy didn't have an isolator until I installed it. I installed a solenoid type.

Unless your truck has a separate circuit for the camper lights that is not turning off when the switch is turned off, the only thing that can run the battery down is if the charge circuit is not disconnecting from the TC.

I have a master 12V disconnect under the sink but that only disconnects the battery from the TC not the truck from the TC.

The TC has a propane detector and possibly a CO2 detector that aren't switched off unless you remove the fuses. They will pull the battery down in a few days.

As someone already said, put a meter on the 12V pin of the truck connector with power off. It should be open if the truck is off. If not your power isolator is shorted or you don't have one.

If that is the case, you can pull the fuses and achieve complete disconnect as long as there are no shorts and nothing has been added without going through the fuse box.

Good luck with the hunt.

An automotive battery can't survive too many cycles where its brought down to totally dead.