I have had my MacBook since 2009 and it's battery is beginning to die. (It needs replaced.) I never use it as a laptop any more, always in desktop mode. So can I continue to use it plugged in to the wall if and when the battery eventually dies completely, or do I need to take it to an Apple Store and get it replaced? If I was unclear, by battery dyeing, I mean needing replaced, not running out of charge.