>But why would I have (apparently) full
>electrons for most of the journey, then suddenly none?

It took 75 miles for the lights, blower, defroster, etc. to drain a
strong fully charged battery.

As for why the alternator suddenly stopped charging the battery, perhaps
the snow and ice accumulations worked some strange incantations on the
electrical system?  Winter sure does strange things to vehicles, I could
tell some stories..........

Good luck figuring this one out, rev up that voltmeter!

Best wishes,

Tony

Anthony L. Mourkas
Hampden, Maine, USA
1984 Vanagon Westfalia (hibernating)
1987 Vanagon GL Syncro (clutch woes)
1991 Jetta Eco Diesel (just keeps on trucking, even at $1.88/gal)