One things I would definitely do is check each connection between the alternator and ground, battery, or anything else it connects to.

On my BMW 320i, after I had an alternator shop install a new alternator, the car would run fine but the battery wasn't getting a charge. I remember the VM showing that the battery was getting about 13.85vDC.

It turned out that the person who installed the alternator didn't tighten down the grounding wire on the alternator, so there was only enough current to keep the ignition and lights going. I tightened the nut and it has worked perfectly for 20,000 miles.

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Aaron
'84 300D 267,000 - Running WVO - Rice Bran Oil - Mmmmmm, fishy...
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