More on PowerBook Battery Life with Mac OS X

Over the weekend we posted two tips to increase a PowerBook's battery life with Mac OS X during sleep. We found that turning off the AirPort card before sleeping our PowerBook 2000 (FireWire) had a major positive effect on battery life. This implies that AirPort continues to work while our PowerBook sleeps. Others have posted that certain drives in the PowerBooks' bay also draw power during sleep and some claim certain screen savers continue to work as well. We unable to confirm either of the latter.

Of course, using previous versions of the Mac OS we always turned off AirPort (actually all networking including AppleTalk) while on our PowerBook's battery to squeeze every last ounce of battery life out of it, especially the 2400c, but we never noticed any perceptible effect during sleep. This is a significant bug that we hope Apple will address in a near future Mac OS X update.

We decided to take our PowerBook 2000 (FireWire) running Mac OS X, instead of our 2400c, on our current airplane trip to the West Coast to give X more of a test in battery mode. We reported on a previous short trip that the 56K modem worked well with Mac OS X in hotel rooms but that trip did not include a long airplane ride. We also previously reported that by using full conservation (dimming the screen as much as possible and using processor cycling) on our PowerBook 2000 with Mac OS 9.1 that we got a little over 3 hours use plus a couple hours sleep time counting both ends of a coast to coast flight. There were still 20-30 minutes left on the battery indicator when we finally plugged the AC adapter in.

How did Mac OS X fair? Almost as well. After a couple of hours sleeping we woke our PowerBook on the airplane to find the indicator stating that barely over 3 hours remained. We used the it off and on for a solid 3+ hours during the flight as we did previously with Mac OS 9.1. The battery life indicator showed 40 minutes left when we put it back to sleep for landing. Barely an hour later, the sleep light stopped pulsing and we could not wake up the PowerBook until we replaced the battery.