Though battery problems are often associated with cold weather, heat is also an enemy of car batteries and will take a toll on performance and reserve capacity. It is recommended that vehicle owners have their car battery tested after two years of ownership and then every year after.
Heat kills batteries, many times in cold climates your battery fails to start your car on a below-freezing day. The reason this happens is that the heat of the past summers has weakened your battery. When you use it in the cold, the starter requires more electrical current to turn over the cold engine with its thickened oil.
Testing a battery’s performance and reserve (or amp-hour) capacity is not just a matter of seeing whether it will hold a charge (or checking the electric eye found on some batteries to see if it is green), so testing is best done by an auto technician.