Correct voltage from alternator?

[bmdubya1198]

The engine was running when I tested the alternator. It was not running long, but it was running. It was still warm from earlier.

[bmdubya1198]

I think you have two things going on, electrical radio problem and a different idle problem

Clean your IAC valve ( sneer) and are you stage zero on everything else?

The white residue is tears collected from the floor of the BMW parts counter.

Hahaha
IAC is clean, and everything else is stage zero. Literally the only two things I haven't done are the timing belt and transmission fluid change.

[bmdubya1198]

I replaced the alternator yesterday with one from the junkyard. Once I got the old one out, I brought both to Autozone to be tested, and they said both are good.
Once I started the car with the new alternator, it showed 13.9-14.1 V on my OBD reader and Torque app. However, the alternator is pretty loud now. The bearings sound pretty worn out, but apparently it's good.
At one point while it was running, my interior lights went out and came right back on. Then when I turned on the headlights, there was a drop to 13 volts, then it slowly climbed back up to about 13.8. Turned on the rear defrost, same deal.
Could it be the voltage regulator? I removed the regulator on both alternators and the brushes are unevenly worn. The lower brush is worn lower on both, and the lower brush was definitely worn lower on the new one than the old one.

[bmdubya1198]

Did another drop test today.

0.07 V at idle with all accessories OFF
0.34 V heat and fan on high, rear defrost on, headlights on, 2k RPM

As for the negative side, it's fine. 0.03 V with the same things on at 2k RPM.

What can cause this 0.34 V drop? Could it be the voltage regulator? I tested continuity on the positive cable, and from battery positive to starter B+, it's about 0.02 ohms. Same reading from bat+ to alternator B+ and starter B+ to alternator B+. So I don't think the cables are an issue. From what I can see, they are in good condition as well.
I tested the alternator with the procedure in the Chilton's manual, and it's good (within 0.5-2.5 V difference between battery voltage, alternator voltage, and alt. voltage w/ load at 1,500 RPM). Like I said, AutoZone tested the alternator as well and it came back good.

[wizechatmgr]

Sounds like bad positive line from alternator to starter or from starter to battery - assuming yours is like mine...