We went back to the motorhome this morning to see how the batteries held up. There is some good news.
We “programmed” the generator, but it did not run. We wanted it to run if the batteries got below 11.5 volts; we should have set it to 12v. We also think we may have missed a switch to the programming; it’s entirely mechanical. We now know that anything below 12 is a pretty dead battery. Just 12.6 is fully charged, so we’re working with a narrow range and have no way to measure a true level.

You hold down the battery button (circled in green)
and then read the indicators (in the yellow box).
You only get E 1/4 1/2 and Full.
And, if the battery has 12–which is empty–it reads full.
We ran the engine and generator for an hour and drove around some, too. Though the coach batteries were too dead to turn on any lights, the generator started up right away. That’s boggling. Good news is they seemingly had more oomph than they did a few days ago.
We’ll do it all again when we take her for the solar/battery work in a few weeks. Hopefully, they can get us a monitor that works better than the useless thing all RVs come with. The technology has changed, but the industry isn’t getting on board with it. I get keeping prices down, but they cut corners in some really dum-dum ways.
Meanwhile, we signed up for a group camping trip to a wine festival on the west side of the Rockies. It’s not for a few months, but it should be fun.