Jose wrote:
I had an alternator failure once, at night over water coming back from
Block Island with a full passenger load (four in all). In retrospect I
should have tried cycling the master (I may have actually tried that; I
don't remember). My first response was to turn things off to conserve
the battery, and to reassure the passengers that the engine would keep
running without electricity and we were perfectly fine.

So far, so good.

I considered
what drew the most juice and what gave me the most bang for my buck, and
settled on one comm radio, the strobes (which I later turned off), and
the transponder. I told ATC (I had flight following) what had happened
and what I was doing, they were fine with that. ("are you declaring an
emergency?" "no, not at this time").

Again, so far so good.

The front seat passenger startd to feel a little queasy, so I managed to
get the air vent pointing right at him, which helped a lot.

They asked my intentions, which were to continue on to Danbury

Now I'm starting to think there was a bit of get-home-itis going on. I
don't know what you were flying, but BID to DXR is the better part of an
hour in most spam cans. You were going to overfly a half-dozen towered
airports where you could find repair services and rental cars during that
time.

How did you know you were going to still have enough battery in a half hour
to work the radio? Maybe before the alternator went off-line, it hadn't
been charging the battery very well for quite a while and you had a lot
less battery time than you thought you did.

How do you know it was the alternator itself which was at fault, and not
some short somewhere which knocked the alternator off-line and was
continuing to drain the battery?

I know you said it was "clear and a million", but I can tell you from
experience that at night, you probably won't know there's a cloud in the
sky until you find yourself inside it.

DXR has a part-time tower. What if you got there after the tower closed
and didn't have any working radio to turn the runway lights on? DXR is
surrounded by high terrain. Not the kind of place I'd like to be trying to
find a runway in the dark.

You've already got a pax who's not feeling well. What were you going to do
if "a little queasy" suddenly turned worse and you had no working radio to
tell ATC that you needed priority handling at the nearest airport due to an
ill passenger?

Day-VFR by yourself, an alternator failure should be a complete non-event.
At night, it becomes a bit more of an issue. With non-pilot pax (who are
YOUR responsibility), I'd be thinking much more conservatively. With one
of the pax not feeling well, I'd be thinking getting on the ground at the
first reasonable opportunity.