So it started a few weeks ago it would stay at about 14v when i had it over 2000rpm or it would drop to 12v then slowly die. I relocated the battery to the back bin about a month before all this went down without issues (fyi)

So i replaced the alt thinking it was the volt regulator. Upgrade to an S5. Now when i start the car it will be at about 10v and when i rev it up a little it will jump to 14 and stay until i drive a little bit then it will do down to 12v and with it at any RPM it will stay at 12 or 13ish.

I tested the battery, and it seems like its getting charged but it will veerrrrry slowly die. ex. if i have it idle at 12.80 and let it sit about every 5 min it will drop .01.....

Sorry for the large post i just wanted to get as many details i can fit. Not sure where to go with this.

 

Im going to see if i can get a reading off of the alt once i get home today.

What scares me the most is it isn't a slow up and down it is sharp and you can notice the lights get dim is drops so quick

 

so i got home and let it idle and it is at 12.8 at the batt and 13.3 at the alt.

im going to start checking grounds.....

 

There's a good chance it's the alt or battery, even after replacing the alt. Those replacement alts are a gamble. Have an auto parts store test both for free. Keep your warranty paperwork held together somewhere convenient.

Your grounds may be lousy but still unrelated to the problem. Regardless it doesn't hurt to address them and a variety of other grounds while you're at it. www.aaroncake.net has a grounding guide in the car section. You will need dielectric grease, anti-sieze compound, fine sandpaper, contact cleaner that's safe for plastic, and a few of the store's shortest M6 x 1.00 stainless steel bolts. A thread chaser is nice if you can find one and get a handle that will fit in tight spaces. I'd do all the grounds when you have the time, but a difference in voltage between the chasis and the connector is a sure indication of a bad ground.

 

Check it at the alternator one more time, but this time put your meters negative lead on the case of the alternator for the meters ground. Do this with a hot engine just like you did before. Heat effects the voltage output to some extent.

 

good stuff im off the next few days so ill give the grounding a shot, and get the alt retested at a shop.


That was how i tested the alternator voltage with the ground on the case of it.