Help with a strange electrical issue

[MC Hammered]

Once and a while when I start the car the cluster indicators light up as shown in the picture and the voltmeter shows that there is no charge happening. I blip the throttle and the indicator lights turn off and the voltmeter shows a charging voltage.

The problem does not return for a while and there is no common clues as to when it happens. Engine could be cold or warm, outside temperature cold/warm/hot and it doesn't matter if it is raining or dry.

Belts don't feel loose so other than suspecting the alternator to be dying does anyone have any suggestions as to what is going on?

TIA for any info.

[Cephas]

Alternator brushes look ok?

[5Toes]

^ my thoughts exactly. Super easy to change and affordable. My e34 with its new one was borderline overcharging!!

[MC Hammered]

Thanks for the suggestion and I'll take a look at the brushes and the VR.

I do have a intermittent rough idle which is one of the symptoms of a worn brushes.

[M3PO]

If your alternator is only putting out 11.4V, something is wrong with it.

[MC Hammered]

It puts out 11 and when I blip the throttle it goes to 13.5+

[328ijunkie]

does it ever return to <13 after blipping throttle?

[MC Hammered]

does it ever return to <13 after blipping throttle?

No it does not.

After blipping the throttle once or twice the voltage readings go back to normal. I may have a bit of a rough idle which almost feels like a misfire, but that goes away when I start driving the car.

[MC Hammered]

My friend helped me extract the alternator and along the way I snapped the main power stud. We checked the brushes and they were both worn very short, there was oil contaminating the rotor and brushes as well.

Luckily we had a spare alternator on hand, bolted it up and when I start the car I read a solid 14.0V output vs. the variable 12.5-13.7V range I have been seeing.