How To Prolong The Life Of A Lithium-Ion Battery
As you may know, just about every modern laptop uses a lithium-ion powered battery. What you may not know is the care for these types of batteries differ from their NiCd predecessors. That said, it is important to give your battery proper care to get the most life out of it possible. A great article on this subject can be found at Battery University: "How to prolong lithium-based batteries".
A few notes from the article:
A lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible. Instead, charge the battery more often or use a larger battery. There is no concern of memory when applying unscheduled charges.
Aging of lithium-ion is an issue that is often ignored. A lithium-ion battery in use typically lasts between 2-3 years.
If possible, store the battery in a cool place at about a 40% state-of-charge. Some reserve charge is needed to keep the battery and its protection circuit operational during prolonged storage. Avoid keeping the battery at full charge and high temperature.
Removing the battery from the laptop when running on fixed power protects the battery from heat. With the concern of the battery overheating and causing fire, a spokesperson for the U.S. Consumer Product Safety Commission advises to eject the battery of affected laptops and to run the machines on a power cord. It should be noted that on a power outage, unsaved works will be lost.
Overall, I would highly recommend reading this article as it has some very good information. While some of it may not be practical for everyday use (i.e. remembering to disconnect your battery when running on power with a full charge), it does provide some valuable information to consider. Overall, your laptop will most likely outlive your battery, so keep this in mind.