Buy a replacement battery.
Laptop manufacturers sell them. Retailers such as Best Buy do, too, but only for select models of major brands such as Dell and HP. You can also check out online battery stores such as www.laptopbatteryexpress.com and www.laptopbatterystore.com for a more extensive array of Macs and PCs. Prices vary depending on the PC, the battery’s voltage, and the retailer. Laptop Battery Store, for instance, sells replacements for $45 to $73, while Best Buy’s cost between $79 and $119, though its selection is more limited.
Many notebook manufacturers also sell extended batteries, which have nine- or even 12-cell capacity, providing a boost over a standard six-cell or older three-cell battery. In our recent review of the Lenovo ThinkPad X220 (p. 30), a nine-cell battery added about 5 hours of battery life, while a 12-cell battery added roughly 12.5 hours. Sometime, companies also sell so-called battery slices, which you can snap in alongside a battery. In the case of the X220, this added another 5 hours.
Tweak the settings.
Both PC and Mac owners will find a preset power management setting designed to conserve battery life. Under this setting, the computer will go to sleep sooner and the display won’t be as bright. You can also manually lower your screen’s brightness. PC users can click the battery icon in the system tray and then select “Power Saver.” If you own a Mac, click the battery icon in the upper left-hand corner of the screen. Then click “Energy Saver Preferences.” When the energy settings menu appears, type either “conserve power” or “conserve battery” into the search bar in the upper left corner of the box. This will make your Mac more energy-efficient, putting the hard disk to sleep when possible and reducing the screen’s brightness before putting the display to sleep.
Let your PC improve itself.
Windows users can have the PC diagnose energy inefficiencies on its own, and then adjust the settings accordingly. In Windows 7, go to Control Panel > Troubleshooting > Systems and Security > Improve Power Usage. Then click through the on-screen dialog box.