+1 on Cycle Electrics products.

 

Check grounds and connections after verifying the battery is OK. 04 Road King the plug connector at the regulator was getting loose at the terminals inside, about 12 volts output checked at the battery motor 2000 rpm yet the stator checked good and would output the correct ac volts per the shop manual requirement.

My clue was that I had unplugged that regulator connection several times while working on the front motor mount. Those are some little pins inside that plug. I took an oring pick and gently forced the female pieces closed together, there was no corrosion. Fixed - back to 13.2 to near 14 volts running checked at the battery.