Possible Duplicate:
Is it better to use a laptop on battery or on AC power?
I have HP dv6 i7 and I work on it for almost 15 hours constantly. Due to power problems in my area because of electricity load shedding, I keep my laptop plugged to power even when the battery is fully charged.
Plugged in all day: - It's a complicated question, with even more complicated answers, since different manufacturers give slightly different answers: Lenovo and Dell reportedly say your battery should be fine if your computer stays plugged in; HP says you should remove the battery if you are running on AC power for weeks at a time; Apple suggests you should unplug and run off the battery every once in a while.
Safe to use for 15 hours a day - Yes. As long as you have it properly ventilated e.g not on a bed or something else that would block the vents.
I wouldn't recommend leaving a battery overcharging all the time, I would decharge at least once a week to refresh the charge. In saying that, i wouldn't do a complete decharge only to 10-15%.
Once a month perform a complete decharge and overnight recharge.
I would recommend getting a UPS which will assist in keeping the power clean, backup power available and you can maybe limit the time on charge.
Laptop plugged all the time is completely safe but it is reduces your battery life.
Try to discharge once a week.
You can also try Lifetime optimizer that will keep your battery always at 70%-80% and it will never be fully charged.
And for laptop to use 15 hours a day is also totally safe.
