So the team from BMW came by last week to verify their plan of adding a buck transformer to lower my line voltage. Yes, of course it worked to fix the problem with the fast charger not starting. The electrician will be coming back in a week or so to install the smallish transformer permanently.
I assume the six of us with this problem all had positive results from this test. This is really a work-around and not a root cause solution, but it is good enough for a prototype program. The bigger question in my mind is whether the analysis they have done explains what Mike and myself and others have observed:
1) Waiting will allow the car to start charging even if the line voltage is still higher than nominal.
2) The problem is worse in the cold regardless of line voltage.
3) When the voltage is really high and the temperature really low, there are three stages of symptoms: No response at all, then after waiting awhile the car will blink once and wall box will shut off with the red light, then wait longer and the car will blink several times before stopping while the wall box stays on. Eventually if you wait long enough the car will charge normally.
Of course this might only be if the garage is warm enough and the only real variables are voltage and temperature.
But hey, the problem solution is complete. All I care about is soon I won't have to turn on the 8000 watt sauna heater in the basement to pull down the line voltage far enough to get my car to start charging.
But the good folks at BMW might want to dig a little deeper. Cold weather performance is what separates the Men from the Boys, as they say.