I know that batteries have a limited life and gradually become less efficient over the years. I follow Apple's advice of running the battery completely flat every few weeks, but can anyone tell me which of the two procedures will make my battery stay healthy the longest. A - keep the mains adapter attached whenever possible to keep the battery at maximum charge as much as possible. or B - only connect the charger sometimes or when the battery starts getting a bit low. Will one routine make the battery stay healthy longer or doesn't it make any difference? I've followed a lot of people's advice and just got a second battery for my black Macbook. Should I now swap them over on a regular basis?