Changing your car battery yourself can save you time and money and can be done in just a few minutes. You will need to make sure the vehicle is in park and the engine is off. Make sure you are working in a well ventilated area. remove the battery terminal ends and the battery hold down straps. Install the new battery in the reverse order. You will want to clean the terminal ends before reinstalling them and apply a small amount of grease on them to help prevent corrosion in the future.