sorry i'm a bit new here, so i never saw the earlier posts... i have some questions:
1. if the battery is fully charged and you leave it plugged in, won't that be overcharging the battery and won't it decrease the battery's longevity?
2. if you charge the battery only halfway and have to stop charging because you need to bring the laptop away from the power source, does that decrease battery longevity also?
3. i heard that lithium batteries should never be completely discharged. so is it advisable to start charging when your power falls to 20% and not let it completely discharge except to callibrate it every few weeks?
Standard Maintenance
For proper maintenance of a lithium-based battery, its important to keep the electrons in it moving occasionally. Apple does not recommend leaving your portable plugged in all the time. An ideal use would be a commuter who uses her MacBook Pro on the train, then plugs it in at the office to charge. This keeps the battery juices flowing. If on the other hand, you use a desktop computer at work, and save a notebook for infrequent travel, Apple recommends charging and discharging its battery at least once per month.
doesn't this contradict what you guys advised earlier?
the key words there are "all the time". its ok to leave it plugged in overnight say or for a couple of days if at a desk. just make sure your calibrate it once a month. you may need not to calibrate it anyway if your using it mobile as depleting the battery will count as a calibration. also be aware that the ultimate killer of a lithium battery is charge cycles.