Tach reading high

Thanks Del the alternator is "newish ". No noises and elec shop gave it a clean bill of health.
Here is a quick video I did last night, I shut car off before symptoms arose again.
With VR plugged in, it "loads" the engine so to speak. RPM drops and alt stud voltage goes up as does the battery running voltage. This is with no load applied.
Once I reinstall alt I will chk/test from batt +ve to alt stud.
Not sure why my AC test from alt stud to ground was wonky? I dont necessarily have the greatest meters??
AC or DC voltage being measured from batt +ve to alt stud?

67Dart273 said

Steve maybe there is a large drop in the charge path from the alternator to the battery. Clip the meter to battery positive, and the alternator stud. Run the car and turn on loads like lights, heater, whatever, and run engine on fast idle. This will give you an idea of the drop in that line. I don't know why the ripple reading is so ???

The ripple reading you mentioned is the NEW alternator?

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