Sorry, I sold my camper over a decade ago (still miss it), but I seem to recall that it didn't charge off AC either.
There was a separate "camper equipment" manual covering these systems that Winnebago (not VW) put out, and I believe it had wiring diagrams, etc. Perhaps you can find one.
It seems like GoWesty is the source for camper info at this time, and they have a tech article on the AUX battery charging, that again just refers to charging off the alternator, so that may be the only way provided. But you could use a charger plugged into one of the AC outlets when the camper is on AC power: http://www.gowesty.com/tech-article-details.php?id=90
There is an internal fuse in the power supply which has probably blown. You can remove the power supply and replace the fuse or replace the entire supply. When that fuse is blown the battery will not charge when plugged into shore power but will still give you 12v in the camper, because it has two separate 12v outputs. The battery will still charge from the alternator. A newer supply will give you better regulation, (cleaner power) when plugged into shore power, but the main reason I replaced it is for the improved battery charging circuit. I could have just changed the fuse but I installed two new Trojan T-105 6V batteries in the back and wanted to insure that they remained properly charged to extend their life. There is a dual battery box that fit nicely back there to hold both batteries. The power converter is located directly below the propane heater and is fairly straight forward to remove. The new unit I choose was much smaller than the original. There was some slight modifications necessary to the wiring right next to the power supply because the new supply has one 12V output instead of two. The new supply will also need to have a low profile right angle AC plug just like the old supply... in fact I used the AC cord from the old supply to make a short extension cord to accomplish this. and I used a Progressive Dynamics (PD9245CV) 45 Amp Power Converter with Charge Wizard. You could take the easy way out and change the fuse but I choose the slightly more difficult path for the reasons explained above.
as explained above, yes it is supposed to charge while on shore power.
Moreover, the interior lights, water pump, rear dc outlets, heater fan, etc are powered by the converter.
Doing some reading online, it seems that a hi-power resistor in series with the charging circuit is a common failure point.
I never managed to pop that panel open, so I don't know how hard it would be to pull the converter out...
sounds not too hard based on above posting. Maybe I should attempt the repair...
There, they also mention that the LP detector is a constant drain on the battery, and suggest that for prolonged periods of non operation you pull its fuse to prevent draining (and damaging) the battery.
I'm sure it might be a trove for several owners, pardon: operators
Haven't used shoreline power for one year. Now when I plug it in, I get a continuous loud buzz at the power converter, original Magnetek 7274, 20 amp, 110v AC to 12v DC. The buzz freq sounds higher than if it were an imbalanced fan.
Buzzing stops when I push the GFI Test button, restarts upon Reset. No buzzing when I pull the 110v circuit breaker.
12 v DC electrical works fine with charging from the engine alternator. Aux battery tests fine.
110v AC appliances also work, so I suspect the problem with the converter.
The LPG warning fuse is burnt out.
What could be the cause of the buzzing? A burnt out fuse inside the converter?