25 miles into my 30 mile ride home the lights start dimming, then SRS light came on, and eventually the car stalled. I got it push started and everything was bright for a moment then dimmed again. It brightened and dimmed a couple of times by the time I got home (with the lights off.) The alternator light never came on. What could it be? Regulator, brushes, fuses, alternator? Anything unusually different with Mercedes?

I just changed the alternator in my wifes car, could it be something contagious?

__________________
5 speed '91 190E 2.6 320,000 mi. (new car, fast, smooth as silk six, couldn't find any more Peugeots)
5 speed '85 Peugeot 505 2.5l Turbo Diesel 266,000 mi. (old car, fast for a diesel, had 2 others)
5 speed '01 Jetta V6 (new wifes car, pretty quick)
5 speed '85 Peugeot 505 2.2l Turbo Gas 197,000 mi. (wifes car, faster, sadly gone just short of 200k )
5 speed '83 Yamaha 750 Maxim 14,000 mi. (fastest)
0 speed 4' x 8' 1800 lb Harbor Freight utility trailer (only as fast as what's pulling it)