Hi, I'm hoping somebody can help me out here.. I'm about ready to throw in the towel on this problem. I'll have a td;dr at the bottom if you want to skip to that.

So I've had this car now for 7+ years, and in that time I've had about 5 alternators on the car (I don't drive the car super often so i'm replacing alternators about as often as I replace the oil!). After having to replace the alternator the second time, I wasn't too worried about it because I drive down a road that regularly floods a bit and my assumption was that I was splashing water on it. Fast forward several years, and I've now had 5 alternators on the car and this newest one that I got just 3 months ago (it probably has less than 500 miles on it) is bad. Although, this time I don't think it's the alternator itself that is bad. The problem I've had with all of these alternators is that the voltage regulator seems to go out. The voltage starts to fluctuate wildly and It basically looks like a disco party in the car because of all the flashing lights (even the headlights, so I'm sure everyone around me is confused as to why my lights are doing that). While it's usually just the regulator that seems to go out, one of those times when the regulator was acting up the alternator actually stopped working entirely so I was stuck driving home from work with just a battery to power the car. Replacing my alternator always fixes the problem, but I can't keep throwing alternators at the car every year. The most recent time that I replaced the alternator was about 6 months ago or so, and the new alternator worked well, although this alternator seemed a bit weak and wouldn't output a very high voltage at idle (sometimes as low as 12.2 volts). That alternator lasted about 2 or 3 months before I started having issues again. I had a new battery go bad because it started leaking acid, so I got a replacement and that one went bad as well. I checked the voltage on my car, and from the obd2 port the voltage is fine, but from the battery the voltage reading is way too high. The highest reading I got was about 21 volts, but usually it would only get to about 16 (which is still too high). Something I've noticed is that I can let it idle for a while and the alternator will put out a healthy 14.7 volts but as soon as I put it in gear, that's when the voltage shoots up (so I guess when there's more load on the alternator?). I've only observed this a few times because I don't want to start the car very often with this problem, so I've only ran it a few times for diagnostic purposes and quickly shut off the car when I noticed the voltage starting to climb. It seems like there's something in the car causing the alternators to go out, which in and of itself is a problem, but this time it seems like there may be another problem in the car causing the voltage to spike that might not even be the alternator. I'm confused, frustrated, and ready to throw in the towel. My only options are to let a shop deal with it or sell the car, but my experience with letting shops fix issues like this is that many times, they won't. This dealership that I've used has been real good to me and if I can't figure out anything else to try, that may be my next step. I'm really hoping to avoid either one of these options though.

TL;DR
I've had this car for 7 years, and in that time I've had to replace the alternator 4 times(5 alternators in total) because they keep going bad (voltage regulators going out causing erratic voltage in the car). This last alternator has now gone bad but instead of an erratic voltage, the voltage is climbing way too high (21+ volts) and frying brand new batteries. I'm not sure what the issue is, but there seems to be a deeper issue than just a bad alternator.

I really hope somebody can offer me suggestions, give me some advice on what I can do to try and diagnose this issue, or just share any knowledge they have about this because I'm just lost right now. I don't know what to do with it.
Thanks for taking the time to read my post.
-Shannon

 

Tell us about anything else installed in this vehicle . . . big, high wattage stereo system? Do you rev up the motor to high RPM levels that might be overspeeding the alternator?

Rick

 

There's really nothing installed on here that should draw more power. It has a stock speaker system, and nothing additional has been added to it. I do drive the car rough sometimes but not regularly.

 

What does "drive the car rough" mean? Try taking one of your failed alternators to a local reputable rebuild shop and let them look at it for a rebuild with better quality parts. Is the engine compartment wiring all stock and original?

Rick

 

I mean I occasionally get on the gas a bit, sometimes it does see WOT. I don't just sit there and rev the engine up a bunch while in park or anything if that's what you're asking though. As far as anything else under the engine compartment, no. The only thing I can really say about the wiring around the engine is that I've had issues with wires shorting out on more than one occasion, this car seems to like wiring issues. The first issue I had was with a multiple cylinder misfire that I traced to an ac wire shorting out on the engine block. A little electrical tape fixed that. Then a cylinder 5 misfire that was caused by an injector wire shorting. It's possible that this is just another wire shorting out somewhere but I don't know if that would cause the voltage to shoot up really high though? I know it could definitely cause low voltage or even no output from the alternator but I'm not sure if it could work the other way around or not?
Also something I just thought about a little bit ago.. I think when I replaced the alternator this last time, I think I ran the wire from the connector (to the alternator) up against the alternator bracket so it's possible that it could be shorting out on that. I'm still not sure if that would cause high voltage though. If anyone knows if that could happen or not though, I would be interested to know. That probably wouldn't explain all the other issues I've had, but maybe at least this issue with the high voltage.

 

Google your car and look for ground connections for your car. Late model cars can have 15 or 20 grounds. Some are in areas that get corroded from road splashes etc. Find them, take them apart, clean them, reassemble them, slobber grease on them to reduce future corrosion. I've seen this many times.