To answer your alternator question, typically the voltage regulator goes first. I have had this happen on my twice on different cars, without getting the battery light. The voltage regulator limits the output to the battery, from the alternator to about 14.5 volts. It's real easy to check the condition of your charging system. With the car off, the battery should read 12.5 volts. Once started, it should read 13-14 volts. Rev the engine and it should stay the same. Any spikes higher than 14.5, means you most likely have a bad voltage regulator. If the volts don't increase from 12.5, then your alternator is not charging the battery.

__________________
1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member