Depending upon the model, a notebook battery usually lasts from 1 to 8 hours. However, with efficient battery usage, an hour or two of battery power can significantly be increased. You can save battery power by using the built-in battery saving modes and by following good notebook battery-saving practices.
Built-in battery-saving modes are Stand By and Hibernate. In the Stand By mode, open applications are stored in the RAM, the hard disks power down, the monitor switches off, but the processor goes on running. When you again perform some activity of the mouse or the keyboard, then the hard disk powers up, the monitor switches on, and the data from the RAM is activated, restoring your notebook exactly the way you left it.
The Hibernation mode is used when the notebook is left unattended for a long time. The open applications are stored on the hard disk, which subsequently powers down, the monitor turns off, and the processor turns off going in for hibernation. On soft rebooting like a restart or wake up on LAN, the processor turns on, the laptop wakes up, and the same exact settings are restored. Both these modes should be used to conserve battery power. You can...