Your one-year warranty includes replacement coverage for a defective battery. You can extend your replacement coverage for a defective battery to three years from the date of your notebook purchase with the AppleCare Protection Plan. However, the AppleCare Protection Plan for notebook computers does not cover batteries that have failed or are exhibiting diminished capacity except when the failure or diminished capacity is the result of a manufacturing defect. Apple offers a battery replacement service for MacBook Air and 17-inch Aluminum MacBook Pro. You can purchase replacement batteries for late models of Apple notebooks directly from the Apple Store.