I pulled the batteries out yesterday to check the fluid, and they seem fine - all cells are full. I didn't think to check the dates on them while I had them out. I guess I'll be pulling them out again to have a closer look... :-/
Not sure about the STORE/USE switch. I haven't seen one in our AS. We have a main disconnect under the gaucho, right beside all the 12V
fuses, in front of the converter. Also, our batteries are in two separate accesses in the front of our trailer, rather than in the box on the tongue, like others have mentioned. I'm guessing that's because its a Classic, but not sure...
I suspect that the batteries are probably a couple years old, and may be in need of replacement this year. Its also possible that the original converter/charger might be getting a bit tired, so another thing on the list will be to look at 3 stage charging units. Since there is an 80W solar system hooked in, I'd first like to figure out how its wired.
We're planning on taking Wanda back to Can Am to have them look at a few minor issues already, so I think I'll have them go over the electrical system while she's in, and I'll go from there. For now, since we've got a couple trips planned within the next few weeks, I'll make do with things the way they are. We shouldn't need to run the furnace much any more, and we'll have 30A service on our trips, so a small electrical heater should do fine until after she goes in for service.
In the meantime, I'll be reading the electical / battery / solar forums with interest to see what my upgrade path is.
Thanks to everyone for your advice and opinions!