Well as you've probably read, I've been having a terrible problem with my voltage @ idle. When I'm driving it's fine, but when I stop at a stoplight the voltage drops super low and all my lights dim. I now have a sub with 400w amp but the problem was there way before I got that, so that's not to blame. The other day I got fed up so I went and bought a Duralast Gold 105 amp alternator. I installed it but of course it didn't even help. In fact, my voltage now is even lower at idle and I'm idling at 500 rpms!!!!!!!!! I took all the wires off and all the grounds and sanded everything clean; I even put a new connector on the end of the wire going to the back of the alternator...Still no change. Although the other end of that wire was grounded to a bolt which also held the positive battery wire. Not sure if that means anything. Today I went to buy a new plug to go into the back of the alternator..because someone mentioned that could help. But the dude at autozone assured me that wouldn't make a difference seeing as my battery is 100% charged. I also just installed a new starter. Another guy at autozone said it's because my dual fans run constantly with the car on. That makes sense, except for I just installed a switch to turn them on and my voltage is still the same. Anyone with ANY possible solutions, please let me know because I'm at the bottom of the barrel and I have no other ideas Thank you .

new idea:

start pulling fuses for everything you dont need to have it run.

perhaps some other accessory is sucking power?

VERY longshot.....

btw, you dont have underdrive pullys do you?

check ground wire to battery, there should be a smaller one to the body of car as well, if its been replaced maybe wire is too small and you need a thicker one

I went to autozone and I bought a 30 inch 4 gauge side terminal battery cable. I unbolted the screw attaching the black bar going from the AC to the engine. Of course I sanded them both clean. I bolted the bigger end of the cable on there and bolted the other end to the passanger strut screw. So now my engine is grounded as humanly possible. Is this what you're talkin about? Thanks

Pull the top plug off the alt, turn the key to the "on" position engine off and measure with a decent digital meter voltage at the pulled plug pins. One wire should measure what the battery voltage is, the other will be a half volt or so lower. The lower of the 2 is the sense wire. If the sense voltage is missing or very low the alt won't throttle up enough to keep the voltage above 13 when load is heavy. The fans if wired up full time will dramatically lower the voltage which is why I don't recommend doing it. Also, if the battery terminal voltage is low because of a low state of charge the alt will NOT run at full output and it will never charge the battery. Always trickle the battery overnight and make sure it is fully charged and in good condition before trying to diagnose a problem.