The story indicated that our alternator was the real problem...seems as if you solved your starting issue once you replaced it.

Nominal charging voltage at engine idle is around 14.4 volts...your readings seem a bit low, although the 80-amp alternator is correct for your model.

Keep an eye one things to make sure the alternator you purchased doesn't have a faulty voltage regulator. I think your starting problems are solved, though.

Check the condition of your fuses while you're at it...I've had some fuses completely crumble in my hand when I pulled them for inspection...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car