When purchasing a netbook, its battery life should be a prime concern. There are a variety of netbook batteries (3-cell, 4-cell, 6-cell, 9-cell, etc.) and since netbooks can come with different batteries, this fact may make you reconsider the netbook you were originally going to purchase.
Obviously, higher-celled batteries pack more power and can allow a netbook to run for longer periods of time, and the same-celled battery used in different netbooks may last for different lengths of time (a Toshiba NB100 running on a 6-cell battery will no doubt last for a different period of time than an Acer Aspire One running on a 6-cell battery).
Here is a quick comparison of the battery life of some netbooks. They are ranked in decreasing magnitude of battery life.
The test conducted on these batteries includes playing a Windows Media Video (WMV) clip until the battery dies. The power management status was set to “always on,” which is in the middle of the power management spectrum between “max battery” and “home/office desk.” This is to allow for an average estimate between the minimum and maximum life of the netbook battery.
The conclusion of this test is that 6-celled netbook batteries last for well over three hours while 3-celled batteries last for little over two at max. The number of cells in a battery is roughly proportional to its battery life (i.e., a 6-celled battery lasts roughly twice as long as a 3-celled one).