A dumb electrical question (please educate me)

[RedBarchetta]

I recently experienced headlight fluctuations and an occasional sputter/miss at just off idle. Of course I checked for the obvious (loose ground) and discovered that the negative cable on the battery had worked itself quite loose (must be those momentary flat spots upon start-up on the Billboards ).

I admittedly SUCK at electrical. I was always under the impression that once you started the car it was the alternator that generated power to the car, kept things steady, kept the battery charged, etc. How come my headlights were dimming with a really loose connection at the battery? And why would l lose spark at the motor (for a brief instant) during the same condition (once I got going it went away)?

I think I need an education on alternator vs voltage regulator vs battery (again) and how they all interact. This getting older thing sucks, too.

BTW, I re-checked ALL of my other primary grounds and they were clean as a whistle and tight as a drum.

-Dean