I bought a battery from Autozone two years ago. I took the battery in just before the two year free replacement warranty ran out because it would barely hold a charge anymore.
The employee said it wasn't the battery and to have someone look at the charging system. I spent $150, and a day of down time just to have the service center tell me it was the battery. I took the defective battery back to AutoZone and because the free replacement period was now 9 days past they wouldn't replace it for free.
I would have saved more money if I just threw it away. Don't listen to people at AutoZone, they just try and blame someone else for their defective products.