Mazda Repair: Alternator malfunction and repair, check battery, luck chris

Question
Hey Chris,
I have a 2003 Mazda 6i 4 cylinder engine. I just recently saw that my check battery light went off. I took it to get inspected at a non-dealer shop and was told that the alternator is going bad and that my voltage is at 12.5 which is not where it should be. My confusion about all this is that I took my car to the dealer a month before who changed my battery when I found my battery had just died out one night, but no mention of the alternator being the culprit...just a dead battery and that this is normal according to the dealer. Now that I saw the check battery light on, and told what was going on, I am surprised that my car at this age (only 2 yrs and 35000 miles) requires a new alternator. Is it possible the dealer has provided me with a faulty alternator and can I get it replaced through them under warranty? If not, how easily or difficult would it be to replace it myself and can you give me a step by step layout? Thanks, John

Answer
Hi John thanks for asking
a half decent alternator should charge at around 14 volts. And yes this should be covered under warranty by the dealer, take it to them first and see what they say. If they will not cover it them get back to me and i will give you instructions on how to replace it your self.
Good Luck
Chris P