The car battery life span is usually about four years in normal city/country driving. This is because the standard lead acid battery must stand up to not only 200-degree plus heat under the hood in the summer. But in the winter, it must work when temperatures are consistently at or below freezing for much of it. Further, short trips with frequent stopping and starting strain the battery in ways you would not expect. For example, one would think that short trips would not harm a battery, but that is not exactly true. As the battery never has a chance to either get up to proper working temperature or to achieve a full charge. AAA advises changing batteries after three to four years, which is a good guideline.