camper battery charging

If it's a brand new camper it could be a bad converter. I have seen that before. The WFCO units are good but like anything there's bad ones in the batch from time to time.

I actually was talking to someone else I know and he was having the same exact issue as you. Would charge at the campsite but not from his truck. Verified the truck was putting out power. Ended up being a bad converter. I guess there is switching in there for low power draw and it wasn't working right.

Most of the new ones have three modes. Full on in use mode where the fan is always going. There is a low usage mode which is for when you have a draw but it is not very big. The fan may come on but usually doesn't. Then there is trickle charge mode for when you have no draw. The converters are designed to switch automatically between these modes. His wasn't going into the low draw/ low use mode. Basically fridge running only during towing. Sounds like the same thing.

did you get your dvm out and check the 7 pin plug on the truck?
7-way_zps702153a8.jpg Photo by osborste | Photobucket
check for 12v and ground first. then test the amperage with the engine running.

OK, I'm a new Ram owner (2015 Bighorn) but I know a little about trailers.

We used to pull a pop-up with our minivan. I installed a 7-pin trailer connector and batteries on the tongue of the pop-up, so that the minivan could charge the batteries.

I do not know if the Ram 1500 comes with this already built in, but I installed a battery isolator from a company called Hellroarer. What this does is it prevents your car battery from being run down by the trailer by isolating your car battery from the trailer batteries. Current will only flow to the trailer battery if there is an excess of power, caused by the engine running. Otherwise, it will isolate the car battery and no current will flow to the camper. This way you only charge the camper when there is plenty of power to do so.

If you don't have one of these, then you will want to unplug your camper when you get to your destination so that the camper does not draw down the power on your car battery, leaving you stranded.

I agree with RamRodRic - have you tested your 7-pin connector for voltage?