Any particular brand of batteries? I went through 4 DieHard's in 5 years back in the 90's. Finally demanded Sears refund my money rather than paying the pro-rate charge to get yet another DieHard. (They always died just outside the 12-month free replacement period).
Then I put in a DuraLast Gold from Autozone and it lasted 10 years. Installed it when I lived in Colorado, so it lived through -15 degree cold temps for a few years and then moved to Texas where it had to endure up to 114 degree ambient temps and underhood temps that make things too hot to touch.
Same thing happened to me with Diehards. Every time they replaced it it was prorated.
But, I had to replace about every year and a half.
Dave -- I may have been born yesterday. But it wasn't at night.