I've done the battery recalibration several times and use my Macbook Air daily, however I've noticed that the battery gets depleted really quickly. For example today it was charged at 100 percent, then I used it for 5 min and left it alone for a couple hours. Brightness at middle setting and backlight keys deactivated. When I came back to use it again from sleep it was at 63% battery life. Is that normal?