My mazda6 replaced battery on Nov, 2008. Today I replace battery again within 19,000 miles. The Second battery paid around $80 under warranty(23000 miles) .

My dealer wants me to pay 75% parts costs if under warranty which is about $95 or pay around $165 but come with 3 years warranty. Finally, we paid for $165.

How come the life of factory battery is short? How long for your battery last? What other brands of battery is better?

This battery is very small and expensive compare to other cars. I have not replaced my 05 ford five hundred (50,000 miles). I will not buy any new car with this small battery again.

 

A couple of things.. one, I have an 04 6s, the battery is actually comparably large, do you have the correct battery in your car?
Second, all batteries are not created equal. The fact that you are getting a 36 month warranty battery is probably an indication of being a poor choice, mine is a 72 month, although I know I won't get anywhere close to that.
Your battery life will be affected by many things, ranging from how much you drive, to hwo well your charging system is working, to what kinds of electronics you are running and what draws while the car is shut off.

My rec is to get a better battery.

 

After my father drove back from dealer. I open hood to look at new battery. The dealer installed new battery which is not compact compare to original one. The warranty is 36/60. Besides, the new battery is installed under some kind of black plastic box to support installation. The compact one had no such things.

 

so you did have the wrong battery before. That explains a lot.
Regardless, don't expect to get 5 years out of a battery these days, even the good ones.