New alternator battery still not charging
 

I have a 2000 Mazda 626 LX that died on me while driving recently. Put in a new alternator and new battery and it started like it was new. Drove it for about 90 mins and it died on me again so I charged the battery back to full and drove it back home. Tested the battery with my volt meter and it reads 12.06V of DC while running. I tried pulling the negative post off while it was running and it died immediately. I'm not much of a car guy so I'm not sure where to go from here besides checking ground wire. Any help is appreciated

How many volts are coming out of the Alternator?

How do I check that?

Test your voltage while running at the battery side of the alternator. The large cable that bolts to the alternator. Also, the 1970's alternator test of pulling the cable off is a bad idea for todays cars. Can cause a voltage spike to computer based components. ugly stuff