jj;

I agree with all the other posters. Start by cleaning all connections in sight...especially those heavy ones on battery and starter, and reconnect using a film of anti-corrosive grease, not to be confused with dielectric grease*.

The battery is a huge electrochemical reservior which if charged and connected will NEVER allow the electrical system voltage to collapse - even if the charging system fails, you have HOURS (or should anyway, if connections are OK) of power for running the ignition and, and, and! Poor connections at voltage regulator and fuseblock will also cause voltage drops and a poorly charged battery. The OE generator doesn't have a lot of extra output (if any!) to be wasted in poor connections!

I had the (heavy) starting contact inside in a solenoid fail once, falling off and onto frame. This caused an instantaneous massive short on the fully charged battery, indeed causing the system voltage to collapse, the heavy battery cable to superheat, the cooking oil on the ground strap to make a helluva smokeshow, even the temp guage to go through the roof (from heating the metal capillary tube). I had to scramble out and rip the battery connection off before somethng really serious happened...the car, and I did survive...but I wish I had a video of that!

Since your car recovers, I don't believe this to be the problem, but I recount the story because it is another of the few situations where the entire electrical system did collapse.

More details in Gas-Tight-Joint tech article: http://www.intelab.com/swem/gastight.htm

Cheers