I'm using my MacBook off battery power and when it says i have about 35% power left, it will automatically shutdown. I don't get a warning or anything. I remember the battery power used to get lower (5%) and turn red and display a warning that my batter is low. Now it just shuts off all of a sudden. Anyone with any advice? I've tried to calibrate the battery but like I said, it will just go to 35% and then shut off. I've had my MacBook for about one year and the battery when fully charged says (right now) there's 3:52 of power time left at 97%. Thanks.