i have a N900 (4 years) and a N9 (2 years) both always charged to full and waited less than 10-15% to put on charge, both batteries are almost new (N900 lost 3-4% of total capacity and N9 1%) a couple of times happened i had to charge them before the battery was low or remove the charger before full charge, in both cases battery life decreased really faster i also have a laptop, charge period wasn't regular and many times i didn't disconnect the charger; now i don't have a battery anymore: after 7 years the capacity became 0mAh