In general, car batteries should be replaced every four years, according to HowStuffWorks. Conditions affecting the longevity of a car battery include where a person lives, how a person drives, and the condition of the charging system.
The chemical makeup of the battery also factors into how long it lasts. Some batteries may die before four years, and others may last for several years, explains HowStuffWorks. Batteries don’t typically show signs of wearing out, but battery testers can be used to capture the condition of a battery at the time of testing. However, battery tests are limited in what they can measure.