Battery life, and perhaps more importantly battery performance, are a major concern of most mobile Mac users. While Apple portables all have really decent battery performance, able to run many hours on a single charge, the run-time always seems to be just slightly less than you need.
You can extend battery run-time using a host of battery conservation methods, from the obvious to the silly. In this article, we're going to take a look at battery conservation methods that are known to work, even if they may seem unusual.
Extending Your Mac's Battery Run-Time
Getting the best run-time out of your Mac's battery starts with having a battery that is in good shape and calibrated. Calibration is the process by which your Mac battery's internal processor (yes, they do have a bit of smarts built into them) is able to estimate the remaining charge on the battery and predict when the current charge will be used up. If the calibration is off, then your Mac may either tell you it's time to shut down while there is still a good deal of life left in the battery, or worse, tell you it's time to shut down when it really is time to shut down, without leaving you enough time to save your work and end your session.
For this reason, you should always keep your Mac's battery calibrated, starting with the day you receive your MacBook, MacBook Pro, or MacBook Air. Apple also suggests that you re-calibrate your battery every month, but I've found that the need to re-calibrate is highly dependent on how you use your portable Mac. With that in mind, I recommend as rarely as once every four months to as often as once a month, depending on your usage.
You can follow this guide to calibrate your battery:
With battery calibration out of the way, let's look at some tips for extending the battery's run time.
Turn Off Unused Services
Your portable Mac has many built-in services, such as AirPort and Bluetooth, which can be turned off if you're not using them.
You can disable AirPort or Wi-Fi if you're not using this feature. Doing so will prevent your Mac from continually scanning for active wireless networks, or making an automatic connection to a network. Either way, you'll save power by turning Wi-Fi off.
Launch System Preferences and select the Network preference pane. In the Network preference pane, select the Wi-Fi item in the list of network services. Click the Turn Wi-Fi Off button.
Bluetooth is another energy drain that can be disabled if you're not using it. Launch System Preferences, and select the Bluetooth preference pane. Remove the check mark from the On box.
Spotlight is a feature that you might think you'd want to turn off. After all, it routinely accesses your hard drive to track changes to the file system. But while you can squeeze out a bit of extra battery time by turning Spotlight off, I don't recommend it. Many applications, including many applications that have some type of built-in search system, such as Mail, use Spotlight. Turning Spotlight off can cause the search functions in many applications to fail. In some cases, it can also cause an app not to load or to freeze when you try to use it. But if you're determined to squeeze out a little more battery time, try this simple compromise.
Open Spotlight preferences, select the Privacy tab, and drag your Mac's hard drive to the Privacy list. This will keep the drive from being indexed, but it won't turn Spotlight off completely. This should allow many applications to run without crashing, although their search features may still not work.
Manage Energy Use
The Energy preference pane in System Preferences allows you to manage your Mac's energy use. There are multiple options for conserving battery life, including turning off the display and putting drives to sleep. The Energy preference pane is the best place to start with battery conservation:
Spin down your Mac's hard drives. You can use the Energy preference pane to put your hard drives to sleep when they're not being used. That's one good way to conserve battery power, but an even better way is to use this tip to customize when your Mac spins down the hard drives:
Turn off keyboard backlighting. This feature uses an ambient light sensor to determine whether the keyboard needs to be illuminated in low light conditions. I find that the keyboard is lit more often than not, even when backlighting isn't needed. You can turn keyboard backlighting off using the Keyboard preference pane in System Preferences.
Don't use the optical drive. Spinning up the DVD drive is a huge energy user. Instead of using the optical drive to watch a movie on a trip, make a local copy of the movie using a DVD ripper. This will allow you to store the movie on and watch it from the hard drive, which, while still an energy hog, is less of one than the optical drive.
Some Silly Ideas That Work
Turn off background notifications. Many applications have a background utility that runs all the time to check whether the app has any updates pending that need to be installed. These pesky mini apps use your Mac's memory, CPU, and network. Turning them off when you're running your Mac on its battery is a great idea in theory, but there's no central way to do it. Instead, you'll have to check individual apps to see if they offer an option to disable automatic notification of updates. Check the app's preferences or help menu.
White on black display: This is taking battery management to the extreme, but if you can stand looking at white text on a black background, it does extend battery run-time. LCD displays work by applying energy to the individual pixels of the display, causing them to reflect light. When no power is applied, the pixels block the backlight, so displaying a mostly black background reduces the amount of energy the display uses.
To achieve this effect, you need to set your desktop wallpaper to a solid white by using the Desktop & Screen Saver preference pane in System Preferences. Once you do that, use the Universal Access preference pane to set the display to White on Black. This will invert the display colors, making all text white and the white background black.
Personally, I think just turning down display brightness is a more functional choice, but you may have a higher tolerance for visual pain than I do.
Muting sound is another way of reducing energy usage. By turning off your Mac's built-in speakers, the battery won't be used to generate all of the default squeaks and squawks associated with various events. Just hit the Mute button on your keyboard, or use the Sound preference pane to mute the output.
Turn off your mail client's auto-checking for new mail. Checking for new mail uses your network connection (which uses a good deal of battery power if it's Wi-Fi) and spins up your hard drive to write new data if there's new mail. It's easier said than done, but only check your email when you really need to.
There are many more ways to conserve battery power. What are some of your favorites? Let us know by adding your energy conservation methods to our list.