My attempt to leave town in the bus was aborted when the bastard broke down electrically in Calistoga. AAA was able to get it started but with considerable difficulty. I hot-footed it back to the storage yard in American Canyon.
Having just parted with over a grand to a large RV repair shop in Vacaville and gotten stranded anyway, I decided to try to figure this out on my own.
I had heard of multi-meters and even seen them. I decided to get one. It turns out they are relatively cheap and are available in auto parts stores. And one can do a surprising amount of testing of various things with them. There are a number of helpful tutorials online showing how to do automotive diagnostics with a multi-meter.
One can measure the condition of a battery by checking its voltage. The voltage will show whether the battery is charged or discharged and also whether it is rechargeable at all. Voltage across the battery with the engine running will show whether the alternator is working satisfactorily or not to keep the battery charged.
One can test for electrical leaks, called "draws" or "parasitic draws" by measuring the current flow between the positive post of the battery and its battery connector which one has disconnected from the post.
One can also check whether the battery trickle charger is working correctly. If the battery starts out with a modest voltage and then rises to a higher one after trickle charging, the charger is working.
These are all valuable things to know that one cannot learn without a multi-meter. Without one, one is just inferring, a fancy expression for guessing.
I have spent the past week testing out various wrong theories. I am much more confident of my current wrong theory than of its predecessors. Today I am going to try a longish drive around the industrial section of American Canyon and back to the storage yard. If it starts after that, which it did not do in Calistoga, then I will conclude that my current wrong theory is less wrong than the ones before it. The proof, as the French say, is in the creme brulee.