If you’re having a problem where your MacBook Pro seems to randomly shut down when you’re running from battery, then you may have hit some dead cells and lowered the capacity of your battery. I had this problem a few months ago and got to chat to one of the Apple Geniuses (Geni-i?) about it. The problem manifested itself by just shutting down my laptop before it gave me a low power warning or anything at all. The way to tell if you have the same problem as me is:

1. Click the Apple Menu
2. Click “About This Mac”
3. Click “More Info”
4. Select “Power” in the left pane
5. Under “Battery Information” look for “Full Charge Capacity (mAh)

Apparently this number should be up over 5000 on a healthy battery. When mine died, that number was around 3000 from memory. Currently mine is at 5440. If your battery has a low full charge capacity, then it’s likely it failed, and if you take it back to Apple they will (hopefully, as they did for me) replace it with a brand new one, free of charge.

Hope that helps someone.