BMW Repair: 1988 528e electical short??, bmw repair, dead as a door nail

Question
Hello.
I have a 1988 528e with 240K miles. Over the past 2 weeks, the voltage warning light would glow brighter/dimmer as I drove the car. I also found that sometimes when I tried to start the car (turn the ignition), nothing wuold happen--no clicks, nothing. I would return the key to the OFF position, then try again. After 1 or 2 times, it would start fine.
Three days ago I started it (to take it to my local BMW repair man), drove 200 ft, it dies (no warning), just dies. Try to restart--nuthing. Dead as a doornail.
My man replaces the alternator and battery. Sez it's running fine.  So, I drive away.
Two miles later, the voltage warning light flashes Hard and Bright. At the same time I hear static corresponding to the voltage light being illuminated. The light is only on for about 1 second.
About 30 seconds later, the car dies again. Dead as a door-nail. Next, I sit (waiting for the tow truck); about 20 mins later the car starts fine. I drive it for 5 mins...fine. The tow truck drops the car at the BMW repair man. Today, the repair man says that they ran it for 10 minutes and drove it around---they cannot recreate the problem.
IM afraid to drive this car now----Im in Los Angeles and traffic is mad.
Can you please shed any ideas on what might be wrong with my car?
Thank you very much.

Answer
Hi Steven,
Something (most probably a short) is bringing down the electrical system. But it could also be an open circuit.
Continuous voltage monitoring is necessary to the point that the stall occurs. Then check what circuits are down or up
(like horn, lights, blower, etc.)so that you can narrow down the problem areas.
If I have to jump into conclusions, I would check first for intermittent fuses and relays (specially the main relay). Look for burn or overheating marks on both fuses and relays.
Also check ground connections.
This is not an easy job. Good luck.
Tino