There are many laptop battery manufacturers, and even more retailers to buy your laptop battery from. However, your biggest concern in purchasing a laptop battery will be to choose the battery that fits your computer. For this you will need to know the make and model number of your laptop; if you don't know this offhand or don't have the necessary paperwork, check the inside of your laptop's battery compartment while the computer is off and unplugged. There you should find the model number, along with some other information. You may also find the part number of your laptop battery, located on the casing of the battery itself.
When buying a laptop battery, you will probably only have one or two choices that fit your computer. Choose the battery with the longest life available for your computer. There are several different kinds of laptop batteries; because the technologies of each are very different, a laptop must be designed specifically for the type of battery it uses. Most laptops are only designed to use one type of battery technology.
The nickel cadmium battery, known as NiCad (pronounced "Nigh-Kad"), used to be the most common type of laptop battery. Nickel cadmium batteries couldn't hold very much power by today's standards, and could only be charged a limited number of times. NiCad batteries could easily be ruined by being left on the charger after they had reached full charge, or by being recharged before they were completely dead. The latter problem, called the "memory effect," meant that if you recharged your laptop battery before it had run completely down, it would remember the point at which you put it back on the charger, and only discharge that far the next time you used it.
The nickel metal hydride (NiMH) laptop battery was the next step up from NiCad. NiMH batteries could hold considerably more power than NiCad, but they still had something of a memory effect -- although it wasn't as pronounced. Lithium ion (Li-Ion) is the latest technology for laptop batteries; although Li-Ion batteries hold about the same amount of power as NiMH, they are considerably lighter and far superior. The Li-Ion laptop battery doesn't have a memory effect and lasts considerably longer than its predecessors. If your laptop supports multiple types of batteries, and the Li-Ion is one of them, then you should choose the Li-Ion as the best type of battery available for your laptop.
Regardless of which type you have, it's important to properly care for your laptop battery, in order to get as much life out of it as possible. "Conditioning," which means fully discharging and then fully charging the battery, should be done at least every few weeks, as it maintains the full capacity of the laptop battery. Some authorities claim that this is not necessary with Li-Ion batteries, while others maintain that it's a good idea to condition all laptop batteries regularly, rather than simply leaving them plugged into the wall at all times. Your laptop battery should never be stored in an area that drops below 50ºF (10ºC) or rises above 95ºF (35ºC); this means that your laptop should not be left in the car or in a storage area that is not climate controlled. Also, for extended storage of six months or more, the laptop battery should be discharged to 50% capacity and removed from the computer; a battery stored for an extended period of time at full capacity may lose the ability to charge fully, while a battery stored in a fully discharged state may never be able to charge again at all.
