I have a 2009 TL with 38k miles and I noticed this week that my green light on the battery was off completely. After searching here for guidance as to how long I had left on the battery, I wasnt able to find anything concrete and called the dearler. Sussman Acura here in PA said the stock battery is covered for 4yrs unlimited miles. I got mine changed under warranty today in under an hour after they found that the crank voltage was low.

I just wanted to keep any of the 2009/2010 owners updated in case they run across the same thing.