1.Turn down the brightness: The iPhone’s bright, beautiful screen is also its Achilles heel—it puts a tremendous strain on the battery. You can take some of the load off by turning down the brightness control a bit. Select Settings, Brightness, and then drag the slider to around the 25 percent mark, or as low as you can stand.
2.Turn Wi-Fi and Bluetooth off: The Wi-Fi radio on the iPhone makes for much speedier Web browsing than on AT&T’s poky EDGE network, but if you’re on the road and you’re not planning on connecting to any Wi-Fi networks for awhile, turning Wi-Fi off will save you a lot of juice. From the main menu, tap Settings, Wi-Fi and select the “Off” switch. Same goes with Bluetooth; if you’re not using a Bluetooth headset, make sure the Bluetooth radio is deactivated (Settings, General, Bluetooth).
3.Check e-mail less frequently: I’m an avowed e-mail fanatic, and if I had my way, I’d have the iPhone check my mail accounts once a minute (as it stands, you can only check your POP/IMAP accounts once every 15 minutes). But each time your precious iPhone checks for mail, it takes a nick out of your battery life. Select Settings, Mail, Auto-Check, and pick either the “every 30 minutes” or (better still) “every hour” options. You might suffer a little e-mail withdrawal, but you’ll live.
4.Make sure “Auto-Lock” is on: Unlike the iPod, which dims its screen after a few seconds of inactivity even when the player is unlocked, the iPhone will keep its bright screen burning unless you manually press the lock/sleep control (an issue that I suspect will get fixed come the first software update). If you haven’t already, make sure the iPhone’s “Auto-Lock” feature is on: tap Settings, General, Auto-Lock, and then pick a time interval (the shorter the better).
5.Turn off the equalizer: Apple has always suggested turning off the iPod’s built-in equalizer to conserve battery life, so doing so on the iPhone couldn’t hurt. Tap Settings, iPod, Equalizer, then spin the roulette wheel up to Off. You might miss the bass booster, but at least you’ll be grooving for a little longer.