Hack 1.07: Maximize iPhone and iPod Touch Battery Life  

Keep your battery running strong!

ED: again, not really a hack, but good to know

With such high-tech, power-hungry features that you're getting on the iPhone and iPod Touch, it's no surprise that many users don't get the battery life that they'd like to. However, there are a number of simple ways to lengthen the time between charges, as well as prevent the premature need for battery replacement.

Reduce Exposure to Harsh Temperatures

Exposure to harsh temperatures can damage your battery, decrease its ability to hold a charge, and ultimately result in the need for a replacement. If you've ever seen those weird people who keep their batteries in the fridge, you may be surprised to know they're not (completely) crazy--batteries dislike heat. Your iPhone works best in a temperature range of 32° to 95°F (0° to 95°C). When not in use, it can be stored at –4° to 113°F (-20° to 45°C.) However, you should try to aim for 72°F (22°C) when using or storing your iPhone. When charging your iPhone, make sure that it's in a well-ventilated place. Charging heats up the iPhone, and if it's in a confined space, the heat won't be able to dissipate, and overheating may result.

Lock the Screen When Your iPhone or iPod Is Not in Use

The iPhone screen already blanks out when you have it to your cheek, but if you drop it in your pocket, it may burn uselessly bright for a while. Leaving your iPhone's screen on constantly drains the battery. When it's not in use, briefly press the lockbutton on the top of your iPhone to lock the screen and conserve battery life.

Turn Off Email Autocheck (iPhone Only)

If you're not an email junkie, you may be satisfied having your email refresh only when you go look for it. Turning off email autocheck (or reducing it from every 15 minutes to once an hour) will reduce the amount of network traffic that your phone is using in the background, and thus reduce both Wi-Fi and cellular radio energy.

AU: Push email also kills your battery

Turn Off Wi-Fi

Wi-Fi drains your battery, even if you're not connected to a Wi-Fi network, because the iPhone is constantly looking for open hotspots to be ready the moment you want to jump online. It also hunts around for familiar networks to fetch your email. When it's not in use, turn this feature off from the Wi-Fi Networks screen in your iPhone's Settings.

Turn Off Bluetooth (iPhone Only)

Bluetooth uses up battery power, so turn it off when you're not using this feature. Go to the General section of your iPhone's Settings and select Bluetooth to turn it off.

Turn On Auto-Brightness

The brightness settings can also drain the battery. Turning Auto-Brightness on will help optimize the brightness level to help use as little power as possible. Turn on this feature by going to the Brightness section in your iPhone's Settings

Turn Off Equalizer

Using EQs for song playback decreases battery life. If you're not using it, or if you would prefer to save that energy, go to the iPod section of your iPhone's Settings->EQ and turn it off.
 

Turn On Airplane Mode (iPhone Only)

If you're using your iPhone as an iPod, or if you're in a movie theatre or in a meeting, and don't want to be disturbed anyway, you'll get a lot more power out of your phone by turning off the wireless capabilities altogether. The iPhone will significantly cut back on its energy use in Airplane Mode. If you're running low on power and you don't need to take calls, this is a way to stem your power loss until you can plug back in. When you want to exit your cone of silence, run any network-accessing application or try to make a call, and your iPhone will politely ask if it can go back online.

Charge Everywhere

Any mobile phones that have to do more than make phone calls--so-called smartphones--are liable to require a daily charge if heavily used. Wi-Fi and 3G signals take energy, you know? One way to reduce that tethered feeling--that "ARGH! I have to charge this thing every day!" sense--is to allow your iPhone to graze for energy, eating lots of little energy snacks throughout the day.

If you're an iPod owner (and chances are ridiculously high that you are), you probably have a lot of old FireWire and USB chargers lying around. Fortunately, the iPhone can use all of these. By letting your iPhone sip the USB power on your laptop when hanging out in the coffee shop or sitting in your cubicle, and letting the iPhone drink heartily from the cigarette lighter adapter or iPod dock in your car, you should be able to create an environment where your iPhone never really asks for a recharge.

That said, the iPhone lithium-ion polymer battery does have special dietary needs, so make sure that you don't forget the final tip in this hack.

Cycle the Charge at Least Once a Month

Contrary to some fears, there's no problem with keeping the iPhone constantly topped-off by plugging it into any available iPod charger in the car, home, and office. Nonetheless, cycling the charge does help extend the battery life. Cycling the charge means allowing the battery to lose its charge completely, followed by fully recharging it. Following this tip will prolong the lifespan of your battery and keep your lithium-ion battery limber and in shape.

If you ever need to replace your iPhone's battery, you can refer to Hack 13.07 Replace Your iPhone's Battery for instructions on how to do so.