Shutting down your Wifi
The easiest thing you can do to immediately increase your battery life is to shut off Wifi on your device. In order to do this, you must hit the home button to get to your home screen, then tap on the Settings Icon (picture of grey gears). From there, Wifi will be the second option, and tapping on it will bring you to Wifi options. There, you can tap on the On-Off slider, and switch your wifi to off if it was on. While the device comes with Wifi on by default, if you aren't regularly using a Wifi connection to reach the internet, then the phone will waste a significant amount of battery searching for available networks. As you walk around with Wifi on, your device will periodically check every few minutes to see if there is a network to connect to. Additionally, if you go into a mall or somewhere with a lot of networks, your battery will drop much quicker as it searches and notices all of the available networks.
Only Bluetooth When You Need It!
The next thing that you can do to help your battery life is very similar to shutting off your Wifi, but this time it's turning off your Bluetooth. For the most part, Bluetooth is used to connect to a wireless headset and occasionally to your computer if you want to wirelessly transfer a file. For most users, you won't need this switched on unless you are currently using a headset. To turn Bluetooth off, you must first go into Settings, and then into the General tab. Then click on Bluetooth, and slide the control switch to Off if it is in the On position. Just like the Wifi signal, if Bluetooth is on, your phone will be searching constantly for a Bluetooth device which will put a strain on the battery.
Don't Obsess Over Email
If you have a lot of email accounts, or even simply one, then email might be what's causing your battery drain. In order to remedy this, again go to your Settings, and then tap on the Mail, Contacts, Calendar tab. This will bring you to a list of your emails, and just below that list is an option for how often to "Fetch New Data." This is the setting for how often your phone wakes up and searches for additional email. If your phone is set to "Push" then your phone receives an email the second that it is sent to you, which means waking up much more frequently. However, if you turn Push off with the control switch, and then instruct your phone to Fetch New Data every thirty minutes or so, then you will save a lot of battery life. Instead of constantly being connected to your email, it will only check every half an hour. This may be more inconvenient for some, but many people don't feel the need to be constantly connected to their email.
Location, Location, Location
Lastly, and along the same lines as Wifi and Bluetooth, Location Services is another area that will drain your battery. If you have location services on, you will be surprised at how many different apps access your location and therefore turn on your GPS. This is a huge drain for the GPS to lock on and transmit your location, and if it is engaged continuously, your battery life will begin to fall very quickly. In order to turn this off, simply go into Settings, and tap on the Location Services tab. Not only can you turn the whole GPS off, but you can also limit what applications can and can not access your location. For instance, if you see an application that is virtually unrelated to location, but it still wants to know your location, you can simply tell Location Services to deny that application access.
Toggle As You Go!
With Location Service, Wifi, and Bluetooth, it is important to remember that you have these options. Wifi can be beneficial when you need to download applications directly to your iPhone, and you have an available network at home. Bluetooth is useful for using a hands free headset while driving or multi-tasking at the office. Location services comes in extremely handy when navigating to different areas, or finding out the location of your destination. These are all benefits of having an iPhone, so remember to turn them on if you would like to use them. After you are finished, simply switch them off, and continue on your way!
In Case of Emergency...
In an emergency situation, you can also go into Settings -> General -> Network and switch off the 3G network. This will significantly affect the speed of your internet connection, but if you are trying to squeeze the last bit of juice out of your phone, this is the most useful way to do it. While in most normal situations this is unnecessary, and downright inconvenient for regularly using apps, it can come in handy when you simply need your iPhone to act just as a phone.
Got it? Get it? Good!
With these hints and tips, you will find that your new iPhone 4 or iPhone 3GS battery life may double. If it weren't for all these radios that broadcast various signals, your iPhone battery can actually last for weeks without dying. When getting used to the phone, it's important to learn about these radios and learn how to manage them to get the most out of your device. Another tip, and the most important of all, is that you should take your battery life with a grain of salt. This device can show you how to drive somewhere, retrieve your email, hold and play all your music, take amazing pictures, and so much more. That all comes with a strain to the battery life, and until battery technology improves, that's just the way it is!