Twenty-five thousand miles and a late-May 2014 purchase. I am still on the factory battery.
Curiously, about six weeks ago I received an alert that the 12V battery had an issue and that "car might not restart." After the service center pulled my logs and called me back, the manager (who was not a tech) indicated that it looked like the battery heater had gone bad.
My car was hauled to Seaside and the battery heater was replaced. I asked the ranger/technician if they would proactively replace the 12V, and he said that they would test the battery to see if it needed replacing. When I received my car back, the battery was NOT replaced.
Finally, the alert that popped up on the dash is just a generic error message to cover several different failures, including a failed battery heater.