Hey man, very good news and well done on the work done.
What was the price on the Voltage Regulator?
Any symptoms of Low Voltage or "Charge battery" errors when shutting the car down before the car actually died?
I get the "charge Battery" sometimes on the M6 when shutting down, so either the battery is not getting charged adequately by the alternator, or, i have a pretty big battery drain, either Comfort Access handles, or a forgotten Tracking unit
Mine had this alarm , of which i still have (Battery need to be replaced now). Do you have the correct ( think 105MAH ) battery, it can also give this alarm. I just need to check but i believe it is the first time the regulator was replaced, milage at 185XXX now. These alternators work hard because of their location, evidence of this was how the cowl looked like when i repaired the snails. Brushes were gone on mine. At agents i paid just below 3K, other auto electrical companies quoted me +/- 1.6K for a Valeo unit but could not source me one. GW only have the complete alternator.
The sequence of alarms i had before shutting down.
Transmission failure ( Orange gear displayed )
Xrive,dynamic, stability, abs Failure
Auto level function stopped working
Electrical system failure
Then the i-drive screen went dead, the odometer stood on 60Km/h even when stationary.
I believe if your case was alternator related you would have been left stranded allready. Measure the voltage while engine is running, should be in the region of 14.2 - 14.7V range without fluctuating. Mine was at 14.7V after replacing (230amp alternator), before replacing it, it had a reading of 15.8V and fluctuated when revving.