Conserve Your Cell Phone Battery When you Have No Signal

Last Updated Aug 3, 2010 11:32 PM EDT

A few weeks ago, I spent a few days in the remote mountains of Washington state, where I had no cell phone signal. But I kept my iPhone turned on so I could take advantage of the phone's GPS navigation. After a day, I discovered that my battery was draining even faster than usual, since the phone had to constantly search for a signal. By day 2, I figured out the obvious solution.

Since there's no signal anyway, I set my phone to "airplane mode," which powers off the cellular, Wi-Fi, and Bluetooth radios. Not only does this bypass the frequent and annoying pop-up messages warning me that there's no signal, but with all the radios off, the battery lasted far longer. GPS, of course, is unaffected because it receives only -- it doesn't transmit.

I recounted this story to my editor when I returned, and she replied, "Even when you're on vacation, there's no escape from Business Hacks research." She's right, and there you go.