Feats of Endurance
Computer manufacturers—Apple included—make certain assumptions when advertising the battery life of their notebook computers, and many users often find their real-world performance disappointing in comparison. Apple advertises a battery life of five hours for their MacBook Pro computers, but you’d be lucky to get 3-4 hours of use most of the time. So, what gives?
The clue is in the small print. Apple’s estimates are based on "configuration and use." Models with faster CPUs and hard drives, as well as larger LCD screens, will use power more quickly than similar models in the range with less extravagant features.
In terms of usage, some parts of the system use up a lot of power, so these are obvious places to look for savings. The backlighting for the LCD screen is one of the biggest energy consumers in the system, so turning the brightness down to its minimum setting dramatically improves battery life. Another major power consumer is the DVD drive, so avoiding overuse makes a big difference too.
Less obvious places to reduce power consumption are the expansion cards. Switch off the Airport and Bluetooth cards if you’re not using them (via the Network and Bluetooth control panes in System Preferences). ExpressCard devices such as modems also use up power when plugged in, even if they’re not actually doing anything, so eject these cards when you’re done with them. Similarly, USB devices such as keychain memory sticks and external mice use up power, so pull them out when not in use.
Applications like Microsoft® Word and Adobe® Photoshop constantly access the hard drive as they create "scratch files" while they work. While harmless enough on a desktop computer, this level of activity rapidly drains the power from a notebook’s battery. So instead of using these disk-hungry and power-hungry applications, switch to lightweight alternatives where possible, such as TextEdit or Preview.
A good trick to avoid using the hard drive too much is to place important files you need to access regularly on a USB or ExpressCard flash memory storage device. While these devices certainly use up some power, they use up less than the hard drive because they have no moving parts. By contrast, accessing data from a CD or DVD is much worse than accessing data from the hard drive, so if you have disks filled with information or media files you need, copy them to the hard drive, or better yet, a flash memory device, before you travel or work remotely.
Figure 4 When not in use, turn off internal expansion cards like the Bluetooth networking card. This will help squeeze out all available power from your battery.