March 21, 1999
by Stephen Hildreth
Editor-in-Chief

Part of the appeal of owning a laptop is knowing that you can work untethered nearly anywhere. There is a price to be paid for this mobility, however, and that's in the form of limited battery time. Whether you're using a 520c or a new G3, simple power conservation techniques can sometimes double or triple the amount of time your battery will last. We've compiled some power-saving steps and grouped them in order of importance. As always, your mileage may vary.

Most important steps:

1) Put your rig to sleep when not using it. During sleep mode, your PowerBook draws almost no power. In many cases, you can walk away from your 'Book for two or three days while it's in sleep mode.

2) Turn on processor cycling. For OS 8.5 users, this is under the 'advanced settings' in the Energy Saver control panel. Other tricks along this vein include reducing the speed of your processor or killing the backside cache.

3) Reduce or turn off the backlight. While you're in the Energy Saver control panel (see previous tip), check 'turn off display instead of dimming.' This will turn off the backlight during low-power mode instead of just dimming it. The backlight draws more power than any other screen component, even at its lowest setting. Active-matrix displays draw almost twice as much power as passive-matrix screens. If you have a passive-matrix greyscale screen, you can turn off the display altogether in direct sunlight.

4) Spin down the hard disk. While spinning, your disk draws a significant amount of power. If possible, spin down your disk when you know you won't be using your 'Book for a while. This tip also applies to CD-ROMs, floppies, and Zip disks. You might also try messing around with a RAM disk, but a RAM disk is mostly a speed-enhancing tool, rather than a power-saving technique, unless you're able to put your System Folder and apps on the RAM Disk.

Moderate power-saving steps:

5) Turn off AppleTalk. You'll find this in the Chooser. The CPU will run a third of the time to monitor network activity if AppleTalk is on. Needless to say, this is a significant power drain.

6) Turn off the modem. Communications and fax programs turn on the modem, so quitting these apps will save power.

7) Turn off ADB and PC card devices. If these don't have their own power supply, then they draw power from the laptop.

8) Turn off virtual memory. VM writes to the hard drive, keeping it spinning. An alternative to using VM is RAM Doubler 8.

Minor steps:

9) Turn off sound. The lower the volume, the less power the speaker will draw.

10) Change your screen color depth to black and white. This speeds video performance (in some apps), while saving only a little bit of power. This tip is mostly pertinent for older PowerBook owners who need every last ounce of juice from their batteries.

11) Save your files less frequently. Every time you save a file, the hard drive spins up.

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