Friday night is Harmonie practice night. So there I am, 11:30 PM, tired, played out, in the car ready to go home. Key in the ignition, turn, and.... gronk. The lights are dim, the starter motor doesn't turn. Flat battery. Hmmm how can this be? The car turns everything electrical off automatically, and I drove here in the daylight anyway.
So having failed to fix the problem with a jump from a friend, he gives me a lift home (thanks Gabriel) and today I return to St Suzanne with the wife to see what can be done. I give the car a good 20 minutes of jump lead connection, and yay! it starts. Nothing too serious wrong with it, then.
We set off to drive home, but the wife reports that at low RPM the car is dodgy, the lights on the panel are flickering, the engine is not running smoothly. (At higher RPM it's running fine) So we head for the garage.
So the symptoms are: Battery goes flat. The most likely possible causes are the alternator failing, or a broken fan belt, or a dead battery. But when the car is revving well, there is plenty of current. So the recharging system is working, so there is probably no problem with the alternator or a fan belt. Diagnosis: failed battery, although why that should be is beyond me.
The car now has a new battery, and it's working fine. If the battery wasn't the root cause of the problem, it should last about a week. I'll keep you posted if problems recur.