rapidly fluctuating charging voltage
 

I tried to check the charging voltage on my 98 Fatboy this morning but the voltage jumps all over the place rather than show a steady charge. Is this indicative of voltage regulator failure or stator? How to tell?

Thanks in advance

Test the output of the stator. If all is good. It's the voltage reg.

I did an Ohm test on the stator connection at the crankcase..it was good. Not sure how to dynamically test the stator. Thank you for your input, much appreciated.

Tested the AC output of the stator, at idle..18 volts and increases nicely as rpm's go up. So will replace the alternator. Thanks for the instruction.

Replaced the alternator..no change. Replaced the ignition switch last year but appears to be working well.

There is a large voltage drop when I start the bike...the draw down on the battery with the bike off is .78 milliamps so I do not think that is the problem.

well, I replaced the entire charging system..I wanted to do this anyway, since the bike has 100k miles on it. But the issued continued..I then went to the frame grounds and sanded the frame as well as combined the ground eyelets into one larger rather than separate. Did this for both frame grounds...voila..now charges consistently at 13.8 volts.