Car batteries generally need to be replaced every 3 to 5 years. This timeframe is a typical lifespan but can vary depending on factors such as climate, driving habits, and battery quality. For example, extreme hot or cold weather can shorten battery life, and frequent short trips may not allow the battery to fully recharge, wearing it out faster. Regular battery checks, especially after the 3-year mark, are recommended to catch early signs of battery failure and avoid being stranded. Signs that a battery may need replacement include slow engine cranking, dim headlights, and electrical issues. Maintaining and monitoring the battery can help prolong its life and determine the best time for replacement to ensure reliable vehicle operation.