Since the SP4 core i5 is a pretty expensive acquisition in my view I am a bit concerned that the battery on this thing will crap out way too early and since it's not user serviceable I have a few questions... I mainly use my SP4 at home with the charger on, I take it that this does not use up a charge cycle, however I know the battery has a lifespan by age as well regardless of cycles. - How many charge cycles can the battery take? How does age affect battery performance? - What are the options if the battery dies out of warranty?