I have a 2006 c6 z51 corvette. So my service charging system came on as i was driving. Determined it was a bad alternator swapped with a brand new one Worked for about 2 hours then quit working. Upon troubleshooting the voltage regulator went out on it. I figured GM gave me a bad part so i had the alternator swapped with a new one and the same thing happened to this one. Does anyone have any suggestions or opinions as to what can be happening here? Not sure why it would be doing this the battery is ACdelco and only about 4 months old. The alternator is the correct one 14v 145A. Im not an expert i appreciate any advice i can get!

 

Check the wires at the starter. This is a known problem area for voltage drop.

 

I once had three new alternators (remanufactured) for a 68 Camaro all fail like you described. Turns out the company who rebuilt them for NAPA got a bad batch of rectifiers. Every one they had in their warehouse was defective, but nobody knew it.
I would try a different alternator from another source.

Garry

 

How did you determine that?

 

I talked to a couple mechanics and they said check all the wires see if there's a break somewhere.

 

Check all the wires? ... Which wires?

You mean the wires that attach to the alternator? ... Just because one of the wires that attach to the alternator is either disconnected or broke don't mean that the alternator itself is bad.

I think these 'couple of mechanics' are feeding you a line of BS.

So, did you find any 'broken' wires?

 

I will have to check after work today. The whole problem is it's the second new alternator and somehow the voltage regulator is going bad on it idk what could be causing it. Pretty frustrating :/ when I first install the alternator the voltage is at 13.5 then after a short drive it goes down to 11.5, 11.0 and won't charge the battery brand new alternator shouldn't do that so something's wrong just don't know what yet

 

Where did you get your alternator? There are a lot of cheap remanufactured alternators out there with garbage Chinese internal parts. They mostly are found at your local box auto parts stores. If this is your situation get your alternator rebuilt in your area that specializes in this. You can also buy a quality kit and rebuild it yourself. It's not too difficult to do. Or buy a AC Delco unit. Also check for shorts in any of the wiring that may ground out.

 

Not to be a smartass here, but do you know for sure the heavy charge wire actually got connected to the new alternators? Also make sure the case of the alternator is grounded properly. If you are sure of that, check the connections on your starter. The output of the alternator goes to the battery post on the starter, and then to the battery. A bad connection there could look like a regulator problem.
Another way to be sure, is to measure the voltage at the output terminal of the alternator, instead of the battery. If the battery reads 12 volts and the alternator terminal reads 14 volts, you know you have a poor connection somewhere.
Also, most auto parts stores will test your alternator for free, and they can confirm if the internal regulator is actually bad.

Good luck with it, and be sure to let us know what was actually wrong once you figure it out.

Garry

 

Do you have the original spark plugs and wires in the car? Did you do any modification of any kind to the car before this started?

 

Double check the wires attached to the starter solenoid as they are known to have defective posts when the Bakelite cracks and breaks.

 

also check the battery if you start the car with a low battery it puts a heavy load on the alt causing a heavy draw on it thus causing diodes to pop. before starting always charge the battery to full.

 

I appreciate all the advice guys thank you! I'm slowly but surely troubleshooting work makes it kinda hard to find time but I'm getting there!

 

#1...take your car to a good auto shop/retailer and have them check your alternator function. Anything else first, and you are throwing darts at a board, imo.

 

I found the problem everybody! the starter solenoid has 2 post coming out from it the post that has the positive battery cable and fusible link that post was Loose and arching. So I simply tightened the post down cleaned up the area and now the voltage is where it should be everything is working normally and no problems. Thank you everyone for the help and support and all the advice!

 

Some misinformation here, what destroys alternators is opening the output lines to the 'load', or battery being charged. The output current of the alternator is rpm dependent, so even if the battery voltage is quite low, say 10.5 volts with a shorted cell, a healthy alternator can handle being full fielded, generating maximum current at say 1500 engine rpms which will be well below the maximum rated current of the alternator.

Some really good advice is with the car running, measuring the voltage at the battery and comparing it to the voltage at the alternator. The result should be pretty close for a fully charged system. A better test is to measure the resistance between the battery and the alternator. It should be within a couple of ohms, moving the wires around should not change the reading.

Even tested alternators at the parts store can still be defective if the output isn't tested over a range of rpms and evaluated accordingly against a chart for a healthy alternator.

last rule of thumb, parts for an expensive car, purchased from a cheap source, will eventually lead to a cheap car.