Back story: First got the car last august, was fine just needed new alternator. Popped it in, and it worked great. Garaged it for winter, took it out a month or two ago, and after a week it went from 13.5 (about) to 17+. So I figured alternator went bad (and only after a few hundred miles?) so I put in a new one. Was good for a week and same thing happened.

Currently: Every now and then it'll sit at normal while driving around, but most of the time it sits 17.5+ on the gauge. We checked in front of O'reilys with a gauge and it was high. We checked it at the battery. Sometimes if it's idling low (round 500rpm) it'll sit between 13-15volts, but as soon as I rev it to get it back to the usual 750rpms it'll jump back up. I tested at night and the lights do brighten up considerably so the gauge on the dash is accurate.

Any ideas on causes? We're thinking a bad connection or ground somewhere but that'll be a real headache.

Also if I hook up any electronics (like a radio,amp) will it fry it? What about the other stuff seeing as how it seems to be holding up fine when I drive it.

edit in: Oh is there any add on components that will drain away the extra? Like a resistor of some sort to make life easy?

 

Assuming its not the alternator for a moment the way our alternators work is they have 3 wires that they need to work. One heavy wire to charge the battery, one to power the alternator (yes as crazy as it sounds the alternator does need to be powered to generate electricity), and one to sence the battery voltage so that it may regulate the voltage to what it should be. If this last wire were to be disconnected or broken my guess is the regulator would see this as 0V and go maximum effort to try to bring the voltage up to 14 V resulting in your abnormally high output. I would also not run it this way this has to potential to do damage to your electronics. there should be a 2 pin connector on your alternator remove it and make sure at least one of them has 12 V going to it.

 

Alright either today or tommorow depending on how the weather changes I'm going to check it out. So far I try to avoid driving it, and it's also why I haven't bothered hooking up a radio. Any other ideas I can check out?

 

Well just make sure your connections are in good shape (in particularly the red wire in that connector I mentioned as that is the sensing wire). Also if im not mistaken there is a fuseable like on that wire which you may want to check out to make sure its in good shape. Keep in mind fuseable links can look good on the outside insulation but the wire can be melted internally. I would measure for 12 V on the red sensing wire in that connector and start wiggling wires around to see if you can get that 12V signal to drop out indicating a broken wire or a bad connection ect.