Truck Battery Drained by Mystery Camper problem or something in Truck?

[menoco]

My truck battery was totally dead yesterday. Because of past problems with camper I assumed it was camper that had drained truck battery, even though I had installed solenoid last year. Using another car battery and jumper cables started and ran truck for half hour. Starts OK.
Then I checked monitor in camper. It showed that camper battery was at full power! Would running the truck on idle for 30’ be enough to charge up the camper battery? Would not think so.
Now I suspect that problem may not be camper but the electrical system or even our frigid Wyoming weather.
I recently posted about my problems with lights that kept blowing fuses. http://www.wanderthewest.com/forum/topic/9571-fuses-for-interior-lights-keep-blowing/
I was also having a problem with furnace fan that will not stop. I had installed a new thermostat with off switch, but that didn’t stop it. Had to pull furnace fuse to shut off fan. camelracer suggest problem could be a fan control relay and that the thermostat didn't directly control furnace fan.
I hadn’t followed up on searching for light’s short or the furnace fan problem b/c recent snows have meant the top weighs too much to lift.
things to know:

• the fuses for the lights and furnace were out and refrig on off when truck battery was drained.
• the truck has a new battery as of 3 weeks ago. I got the new battery b/c a couple of times in last month, the battery appeared dead, only to start weakly after a couple of minutes.
• camper has new battery as of April.
• We have had a week of below zero morning temps with highs in teens. During the last week I didn’t start or run the truck until yesterday when it was totally dead.
• The camper is plugged into truck. Last resort is to unplug.

Seems like a good pluzzer. What's best theory (or guess)?

 

[PaulT]

Sounds like the truck charging system to me. It should be easy to separate the camper power from the truck at the thermal breaker under the hood. Disconnect there and test your truck's charging system. Either way, it should cut in half the things you will need to look at next. If it looks like the camper is the problem, I'd check the battery isolator in the camper as the camper's batteries apparently did not discharge

Paul

 

[mitch h]

After you check out what Paul said, just double check and make sure the hot wire and ground wire did not get switched around somewhere. Mitch

 

[Wandering Sagebrush]

I agree with Paul, but I would start by just pulling the plug on the camper to isolate things. If the battery runs down with the camper disconnected, check to see the charging voltage coming out of your alternator. It should be in the range of 14+ volts. If it's low, you have a charging issue. If it is sufficient, you might try putting an ammeter (across a shunt) into the battery circuit to see if you have something that is giving you a slow drain when the engine is off. There is probably a slight phantom draw from things like your clock and security system, but that should be really minimal.

 

[Kolockum]

An Ammeter is nice if you don't have one handy you can use a voltmeter (it will show if power is being pulled but not how much). If you do detect a power draw start pulling fuses one by one until the power draw drops off. This will isolate the circuit where the problem is. The first connection I would check is the camper-to-truck as mentioned above.


Good luck