2000 V70XC free-wheeling alternator
 

Has anyone had an alternator that failed to charge because the free-wheeling clutch was slipping at the wrong time?

I have seen one.
But usually what I see when they go bad is when cold it charges. Once the Alt gets hot is stops charging. But it is usually only the regulator and you can replace it.

Yep, it was a bad regulator. Given that it's inconvenient to change, I opted for a Bosch rebuilt. Case closed...