Paul Lipps wrote, "'Guess I don't quite understand the scenario of why the regulator, which supplies the excitation to the alternator field, would get disconnected if the battery post disconnected. "

 

Most alternators will not reliably continue to produce electricity without the smoothing affect of a battery connected to it.  Charging systems assume connection to a battery and are not designed to continue functioning without a one to moderate the output of the alternator. 

 

In my previous example of a battery post breaking off, the alternator would quit, possibly by going over-voltage and tripping the over-voltage disconnect.  Unless the pilot has a backup alternator that is self-exciting or was excited at some point during the flight prior to the battery failure, the pilot is SOL; no battery, no alternator.  The SD-8 permanent magnet alternator from B&C comes with a large capacitor that allows it to function without connection to a battery.  If it's wired with the self-exciting scheme or if it was excited earlier in the flight, the pilot now has the eight amps or so output of the SD-8.

 

Dennis Johnson

Legacy #257, prop installed today and timing the mag tomorrow