A method and apparatus is disclosed to charge a battery. A wall adapter may provide a power to a battery charger in a collapsed mode of operation. In the collapsed mode of operation, the wall adapter may provide the battery charger with a collapsed power. The battery charger may provide a charging current and/or voltage in a constant current charge mode of operation and/or a constant voltage charge mode of operation using the collapsed power. When operating in the constant current charge mode of operation, the battery charger provides the charging current and/or voltage having a constant current until the voltage of the battery is less than or substantially equal to a constant charge voltage. Alternatively, when operating in the constant voltage charge mode of operation, the battery provides the charging current and/or voltage having a constant voltage until the voltage of the battery is less than or substantially equal to a float voltage.