To replace a car battery, first, ensure the engine is off and the vehicle is in park with the parking brake engaged. Locate the battery, usually under the hood, and identify the negative (black) and positive (red) terminals. Remove the negative terminal first using a wrench, then the positive. Carefully lift out the old battery, being mindful of its weight.Clean the battery tray with a mixture of water and baking soda to remove any corrosion. Place the new battery in the tray, connecting the positive terminal first, then the negative. Apply a thin layer of anti-corrosion grease to the terminals to prevent future corrosion.Tighten the terminal clamps securely, ensuring they’re snug but not over-tightened. Finally, start the car to ensure the new battery is functioning correctly, and dispose of the old battery at an appropriate recycling center.