The two most common variables that determine your battery life are extreme temperatures and short run times. 

Cold weather can diminish your batteries cranking power and city stop-and-go driving will diminish your batteries reserve power.  If you drive less than 20 minutes between stops, the alternator cannot fully recharge your battery.  This means your battery is not always at full capacity and that your alternator is constantly trying to make up for the shortfall. It’s best to have your battery tested at least twice a year and to make sure the terminals are free of corrosion.  A well maintained battery will give you a maximum life expectancy and peace of mind.