Not sure if this is the proper forum, but let's see if someone can help me with this problem.
I have 2004 E450 Diesel RV (Fourwinds 5000). The "house" battery will take a good charge when plugged to 100v hookup, and when I run the on-board propane generator.
But when the battery goes low after camping at a no-power hook-up site and drive the truck home I get no charge to this battery. The truck battery charges just fine.
I have checked all the fuses and circuit breakers that appear to be part of this system.
I have read that there is some kind of device that might need re-setting, but I am not sure what or where this device might be ??
Anyone know what this problem might be..

 

Did it ever charge from the truck system?

Most RV motor homes run an isolator to charge the RV battery. Its a BIG finned block about the size of a brick. It has the center post to the alternator and one end post routed to the RV battery.

The other option is a relay that energizes when the ignition is on. My truck uses that method there is a trailer relay in the front power box of the truck.
I would think you RV uses that method.

Look in the owners manual Ford- for that relay and a fuse. In my truck it came as part of the trailer tow package. Should be the same in the RV.

There may be a disconnect circuit breaker under a seat or in the area of the Rv power panels.. some do that. Info on that option would be in the RV manual.

Not much help I bet, but that's my best shot.. for the stock fix.

If you do not have the Ford add-on charge relay.. you should have the charging isolator.. if you do- it could be burned out. They do that all the time..

IF all else fails.. then add a relay.. When I had a MH, I used a HD starter relay - Ford truck. Run NR 10 wire from the truck battery- fuse with a BIG inline fuse like 50 amp, to the relay, then a wire to the RV battery with a fuse at the battery end. Both ends with a fuse.
Connect the relay trigger post to an ignition hot wire from the truck. When you turn on the key - the relay closes and connects the RV battery to the truck battery. Worked better then those lousy isolators.

 

Thanks for your quick reply psdendurance;
1) I got it 2 years ago, I am not 100% sure but I suspect it has had this problem since I got it at 4500 miles ?? RV manual says it should charge from the motor system.
2) BIG finned brick, I did not see this, but everthing is burried in the truck, I'll look again.
3) I checked for this trailer relay - the space is empty.
4) Could not find anything helpful in the RV manual, but will look again.
5) I am reluctant to try any "Add-ons" as this should be part of the original vehicle package.

 

My truck would not charge my trailer batteries after I blew a fuse when trying to start the trailer generator off the truck power. It was a 20A fuse in the panel under the steering wheel. Not one of the common fuses but a fuse that has a little square window to look in. I don't know what you call this type of fuse, but I overlooked it when looking at the common fuses.