A few years back I bought a 100 amp powermaster alt because at idle when my electric fan is on my headlights will dim until I rev the motor. All that time I ran a Delco Alt with no other issues. Changed the alt and was fine until it only put out 12 volts... So ordered a new regulator and fixed it. A few months later it started putting out 18 volts so I went back to Delco The Delco never had an issue unless at idle with the fan in (600 ) rpms or so the headlights go off. So.. decided to buy a powermaster rebuild kit and rebuild it. Went fine and was putting out the right volts and all was right Today went to drive and again putting out 18 volts The powermaster is chrome The Delco is back on and with the right volts So why only with the powermaster would I be having this issue?