Notebook Battery

Notebook computers are getting smaller and more powerful which require batteries that can provide enough power to last without being too heavy. Lithium Ion batteries are used in current notebooks due to these requirements.

A couple of advantages a Lithium Ion battery has over other rechargeable battery types would be:

Higher energy density, holds more energy in the same size and weight as other rechargeable's.
No memory effect, don't have to discharge then recharge to keep the battery in good shape.

There are some issues with lithium ion batteries however:

Expect to replace them every few years since they will eventually quit, they will last anywhere from a couple hundred to 600 or more charge cycles (discharging and recharging).
Aging - even while not in use they can irreversibly lose up to 20% of total capacity per year.

Tips to Extend Notebook Battery Service Life

All rechargeable batteries eventually need to replaced but there are things you can do or be aware of to keep your lithium ion battery operating as long as possible.

Heat is your battery's worst enemy: do not leave your notebook or battery in a vehicle on hot sunny days and make sure the cooling vents of your notebook are not blocked to prevent heat buildup.
If you are not going to use the battery for long periods or primarily use the AC adapter then consider storing it in a cool dry place to slow aging. It is recommended to keep the battery around 40% charged during this time.
Recharge often rather than draining it completely before recharging.

Buy a Spare Battery?

Due to the aging issue mentioned above you should only buy a spare notebook battery if you really need one (constantly running out of power while on the road with no option to use AC adapter). If you do decide to get a spare be sure to check manufacture date to avoid old ones.

Battery Operating Time Tips

There are little things you can do to increase run time such as lower your screen brightness in low light conditions, switch off or remove the wireless network card if there is no access point nearby, make sure all power saving features are enabled, and unplug anything unnecessary or not in use such as PCMCIA and USB devices.