Charging issues....

my alternator took a crap batt light came on it wasnt charging so i put another alternator was charging fine for 2 days then the voltage gauge drops to the second line from the bottom up and if i unplug the negative while car running the gauge goes to the middle like normal and if i put the negative back it drops anyone knows this .....
 
I had the same problem last year i got one from autozone ..it did good for two days then the voltage regulator went bad. So i had the guy at autozone to test the replacement alternator before i went home and it was bad just like the one i got before. Well long story short i had to drive 5 mile to another autozone to get a alternator that tested good.
 
If you ever buy an alternator from autozone/advanceauto always keep the recipt. The one year replacement is a sweet deal.

I've gotten 3 new alternators so far for my 95'. All because I run them into the ground before the year is up;)