I will do some more digging, perhaps there is a make/model on the convertor itself that can be seen. I haven't dug into the spot it is located yet, but appears there is a door of sorts on front of it under a cabinet. Odd little fasteners I'm unfamiliar with holding it on.
So if the unit does not actually sense when the batteries are fully charged, wouldn't this be an issue every time your plugged into shore power, even when out camping? I'd sure hope that even back in 93, they used the technology to prevent battery overcharging.
I've been keeping it plugged in so I can leave a 120v light on inside the unit for some warmth and to help prevent dampness, or sometimes an electric heater if we have company visit overnight.
Is there usually a way to shut off the convertor's charger feature manually, and still have 120v available in the coach? That would be a nice feature, if it's not automatic.
I have a separate automatic battery charger, which I guess I better hook up to the engine battery from time to time, to keep it up over the winter. It has the auto trickle charge feature, so it won't overcharge it, if say it's left on overnight.
Tenbear, they are definitely two 12 volt batteries in the coach.