Hey,
I had the exact same problem. I was dicking around with my 240's electrical system and killed my regulator. Here's what I did to test and successfully resolve.
Test to see if the battery is being charged with the engine running: Run all the electrical accessories (hi beams, etc) and let the car idle. Come back in 30 or 60 minutes (in your safe neighborhood). Turn the car off, then try and turn it back on. The starter should have very little to no power.
If this is the case-- and your alternator isn't making bad sounds or such, and is spinning, the voltage regulator is likely NG.
Two screws should be holding in your voltage reg on the rear side of your alternator. Take the little guy out and replace it.
Edit: Hey, I just noticed you live in Alameda. I lived there for the 1st nine or so years of my life. Should still be safe neighborhood!!
