A good car battery warranty is important to ensure you won't be out money if something goes wrong with the battery. The best car battery warranty is offered by Exide on its Marathon battery. It offers a 40-month replacement that is absolutely free with the return of any defective battery. In addition, the company offers a 108-month limited warranty covering a variety of other problems and situations. The Marathon battery comes with a 40-month 24-hour emergency warranty and the number is right on the battery, offering you convenience and relief in an emergency situation.