Car batteries require replacement after four years on average, states HowStuffWorks. Dead batteries are usually an indication that a battery needs replacement. Car batteries should be tested using an electronic tester during regular maintenance.
The appearance of the battery and the owner's driving habits can also indicate the need to replace a battery, claims HowStuffWorks. Short trips and long periods of battery inactivity lessen battery life. Starting a car requires a large amount of electricity, which means the battery never gets fully recharged in short commutes. Batteries may also require replacement if there are signs of corrosion, buildup or stains on the terminals. Owners can use baking soda and water to clean up buildup.