The battery on my powerbook (it is a Tibook 867) keeps losing charge after shut down. I just went for a 10 day trip and when I get back the battery was at 80% (that is 2% a day). Is this normal or I should be worried? The powerbook is only 2 months old. Btw, if I disconnect the battery, this won't happen. And if I put it to sleep, it uses approx 15% overnight. At least here I understand why the power is being used, but still isn't 15% too much?