Shore Power 12V to vehicle
I have a new (old) truck camper and am still trying to sort out and fix various items. One thing that I have discovered that causes me concern is that when on shore power, there is 12V being supplied...
Forum Discussion
In general, it should not be a problem. Basically, the higher voltage source "wins" and supplies power, while the other just kind of sits there.
If the converter is not supplying a proper voltage (which would apply to both the camper and the vehicle), then that's a problem that needs fixing in any case. If it's the original converter, it would probably be money well spent to upgrade/replace it in any case as it's likely a single-stage ferroresonant unit. Those sorts of converters do provide a reasonably regulated output--not perfect, but good enough--provided they are in proper working order and the incoming power line AC frequency is correct, which it pretty much always will be for utility power but might not be with a generator. They are, however, not super efficient and heavy and sometimes hum annoyingly.
A bigger concern for me would be that, if not connected to shore power and hence without the converter operating, the camper's electric usage could discharge both the camper's battery and the truck battery, leaving you stranded with no power and no way to start your truck. Adding a relay to shut off the trailer charge line when the engine isn't running is the obvious solution to that problem.
If the converter is not supplying a proper voltage (which would apply to both the camper and the vehicle), then that's a problem that needs fixing in any case. If it's the original converter, it would probably be money well spent to upgrade/replace it in any case as it's likely a single-stage ferroresonant unit. Those sorts of converters do provide a reasonably regulated output--not perfect, but good enough--provided they are in proper working order and the incoming power line AC frequency is correct, which it pretty much always will be for utility power but might not be with a generator. They are, however, not super efficient and heavy and sometimes hum annoyingly.
A bigger concern for me would be that, if not connected to shore power and hence without the converter operating, the camper's electric usage could discharge both the camper's battery and the truck battery, leaving you stranded with no power and no way to start your truck. Adding a relay to shut off the trailer charge line when the engine isn't running is the obvious solution to that problem.
