Automotive batteries can be the source of unnecessary trouble for drivers, especially in extreme weather conditions. The battery is responsible for two functions: it starts your car and also passes along electricity to the electrical components in your car. Extreme heat is more detrimental to your car's battery than extreme cold - this is one reason many car companies are installing the battery in the trunk of the car, away from the hot engine.
Many people mistakenly assume that when a car is running, the alternator powers the electronics in the car - this is incorrect. When the car is running, the alternator generates electricity, which flows to the battery for storage. When you turn on the lights, radio, seat heaters or other automotive electronics, the battery provides the power, not the alternator. The alternator then provides additional current to the battery whenever the engine is running, which recharges the battery.
Car batteries are filled with acid, which allows them to convert chemical energy into electrical energy. It is important also to periodically check the terminals on your battery for oxidation (white or green deposits on the battery posts). If you find that your battery terminals and cables are dirty, clean them with a wire brush and baking soda to facilitate an efficient charging process.
Most batteries begin to significantly lose their ability to store a charge around the three year mark. This does not mean that your battery dies at this point, but it does mean that your alternator and other components in your engine need to work harder to keep your battery charged. We recommend changing your battery every three years to prevent the unnecessary wear and tear on your other engine components. Take your old battery to any car parts store for a credit typically around $7 - $10.
Another obvious benefit of replacing your battery every three years is that you minimize the risk of your car not starting when you need it to. Newer cars have significantly more electronic components that can be damaged by an improperly performed jump start. By minimizing the need for a jump start, you prevent the inconvenience of a dead battery as well as the risk to your electrical systems from a bad jump.