I’ve been going thru their checks - but it’s a bit of a mess because the external voltage regulator isn’t in the loop anymore. I did confirm that the ‘G‘ light bulb that’s in there now is a working bulb, and that there seem to be no blown fuses.I was just going through the Fiat factory manual and noticed that in the Electrical Troubleshooting section (page 221) they have diagnosis procedures for electrical issues you are having (no GEN light and poor charging). You might want to go through the step by step processes in there to figure out what the problems are.
Before I put the alligator clips on the alternator, the ‘G’ light was working, but proper charging wasn’t happening. After alligator clips, ‘G’ light is dead, and the same charging problem exists. It’s possible I shorted out the internal voltage regulator? Would that kill the ‘G’ light?
I also tried your idea of grounding to the case instead of frame: exactly the same voltage readings as if I was connecting my meter to the battery terminals, 12.31v. So no difference whatsoever.
Meter drops BELOW 12v when ignition is switched on, raises to about 12.2v at 1k idle, and 12.7v at 3k idle.
It‘s interesting that switching the ignition on drops battery voltage from 12.31 to 11.97v - that seems like a big drop to just light up the instrument cluster.
It can only be one of two things I think - bad alternator/voltage regulator, or a wiring fault of some kind?
But I’m always ‘all ears’