Help! New Alternator, Voltage Wavers

[syrenmoonflow]

Vehicle: 2000 GMC Sonoma V6

 

So here's the story. My voltage was only at (est) 10 volts on the way home, so I figured it's my alternator.

 

-Changed the alternator (100).

-Voltage was sorta weird, went to get it tested.

-Test said I needed a new battery.

-Installed new battery, new electrical test looked good at idle.

-Took a drive down the block, Voltage wavered quite a bit. I believe it dropped down to (est) 11 volts.

-Went back, they gave me the wrong output alternator.

-Installed the new (proper, 110) alternator.

 

So now, (keeping in mind this is all visual estimations), on startup it's around 14.5 volts. When driving, even at a steady speed, it will randomly move between 12.5/13 - 14.5 volts.

 

Yes it dips at intervals like all GM trucks do when I'm using a blinker, and no, this isn't the problem I'm talking about.

 

Any ideas?

Could the first/wrong alternator fried the new battery that quickly and that's the reason for the voltage waver?

I don't know what else it could be. I was thinking the voltage regulator, but I believe those are built right into these alternators now.

[truffstuff]

are you checking the voltage just by looking at the dash? if so i would grab a multimeter and test the output at the alternator studs to get an acurate reading, would also check voltage at batteries to make sure you dont have any unwanted voltage drop. the guage in your dash could be acting up and not your alt/battery.