If you have the latest 3G iPhone you’re probably annoyed that the battery life isn’t all that you’d hoped for – especially if you are a heavy user.  After doing some research, I gathered my own list of 20 simple tips which have enabled me to greatly extend the battery life on my iPhone.

1. Turn Location Services OFF (Settings > General)

2. Reset Location Warnings (Settings > General > Reset)

Applications that use Location Services are granted permission (by you) to do so. For example, the first time you ran the Maps application – you will have been asked whether to allow the Maps application to determine your location.

The iPhone remembers permissions you have granted so it doesn’t ask you every time, but you can reset these permissions using the Reset Location Warnings function.

3. Reduce Brightness (Settings > Brightness)

The lesser the brightness, the longer your battery will last. Find a comfortable level appropriate for the lighting conditions where you are using your phone the most.      

4. Turn 3G Reception OFF in fringe areas (Settings > General > Network)

If you have a weak 3G signal your phone will be spending a lot of time switching between 3G and 2G/”Edge” networks – which is an unwanted drain on the battery. So if you’re in a fringe 3G zone you may be better off turning OFF the 3G capability in return for longer battery life.

5. Fine tune your email Fetching and email Accounts (Settings > Fetch New Data)

Turn OFF Push Notifications, and try Fetching your new email either HOURLY, or better-still, MANUALLY. If you have multiple email accounts you can personalize which ones are Fetched automatically or manually under the Advanced settings on this screen.            

It should also be noted that just because you may have multiple email accounts set up on your computer, doesn’t mean you must have all these set up on your iPhone.  Use iTunes syncing options when your iPhone is plugged in – select the INFO tab in iTunes, scroll down to Sync Selected Mail Accounts and only select those ones you want synchronized to your iPhone.

Alternatively you can turn individual email accounts “off” directly on the iPhone (Settings > Mail, Contacts, Calendars > Accounts) – select the account, and use the account ON or OFF option.

6. Enable Auto-Lock (Settings > General > Auto-Lock)

Ensure your phone goes to sleep after a few minutes. I fine the “3 minutes” option good for my usage.

7. Lock your Phone when finished (SLEEP/WAKE button)

Get in the habit of pressing the SLEEP/WAKE button immediately after you have finished interacting with your iPhone.  Even if listening to music or podcasts, press the SLEEP/WAKE button to put the iPhone to sleep. The audio will continue, and you can use the volume controls, and the button on the headphones to Pause (one click) and Skip (double click).

8. Turn Wi-Fi OFF when not using (Settings > Wi-Fi)

Unless you are using wireless data services in a hotspot, you should turn Wi-Fi OFF. Leaving it on causes your phone to be constantly “sniffing” for new hotspots to join as you roam around throughout the day, which can be very taxing on your battery.

9. Turn Data Roaming OFF (Settings > General > Network)

Turning this option off is one tiny thing the iPhone 3G needs to worry about – I doubt it has much, if any, impact on battery life – but it does make you safe from receiving massive horror data usage bills if you happen to travel outside your country without an appropriate data plan!

10. Turn Bluetooth OFF (Settings > General > Bluetooth)

If you’re not using a Bluetooth Device with your iPhone, turn it off and save yourself some precious battery power.

11. Turn OFF all non-essential Sound Alerts and Vibration (Settings > Sounds)

Every time your iPhone has to do ANYTHING (even make a “click” noise each time you touch a key if you have “Keyboard Clicks” turned on) it is a use of energy, and therefore a drain on your battery.

Turn all non-essential sounds alerts off, and disable vibration unless you are operating in a noisy environment.

12. Turn the iPod’s Equalizer (EQ) OFF (Settings > iPod > EQ)

Running the EQ uses extra processing power when playing your music, and that uses more battery power. Turn the EQ off to extend your charge.

13. Run a Full Battery Cycle once per Month

Apple officially says:

“For proper maintenance of a lithium-based battery, it’s important to keep the electrons in it moving occasionally. Be sure to go through at least one charge cycle per month (charging the battery to 100% and then completely running it down).”

There’s a common misbelief that the iPhone’s battery is lithium-ion (Li-ion), however CrazyGadgetGuru actually states the battery in the iPhone is a lithium-polymer (Li-poly) cell, and has busted a few battery care myths and gives some great advice about extending the life of your iPhone’s Li-poly battery as discussed in The Two Laws of iPhone Battery Care.

14. Limit Video Watching and Gaming on the iPhone

Gaming (particularly games involving 3G graphics) and Video watching are both major drawers of battery power. If it’s critical that your battery lasts the whole day, avoid these activities.

15. Don’t Fiddle!

I know the iPhone is the funnest toy to play with, but maybe you should find other things to play with instead.  All that senseless time-wasting fiddling and flicking around on your iPhone during every spare minute of the day is consuming battery power. My battery always lasts much longer when I’m occupied and doing other stuff.

16. Not all USB charging is equal

Be aware of a few things if charging your iPhone from a computer’s USB port – not all USB ports have the same power capacity. Always use one of the USB ports directly on your computer – don’t charge your phone via a USB “hub” distributor, or from any secondary USB “extension” ports (e.g. on some computer keyboards).

You’ll also get faster backup and syncing when connected into a direct USB port.

17. Airplane Mode can be your Friend (Settings > Airplane Mode)

Airplane Mode is a quick and effective way to turn off all “transmissions” from your iPhone, but using it in other situations can help your battery last. Try using Airplane Mode whenever you don’t want to be disturbed – such as in meetings, or a movie theatre. It’s also a good idea to use Airplane Mode if traveling through fringe reception areas so your phone isn’t continually trying to seek out a weak signal.

18. iPhone getting hot for no reason?  Try a hard reset.

Your iPhone generates heat when it’s processing data – in other words, when its “brain” is working, it gets hot.  If your iPhone is getting hot for no apparent reason, there may be some software running in the background that is caught in an infinite loop or locked-up. All this extra processing will be using battery power – possibly quite substantially, and could be a result of a software error. It will also make your phone seem “sluggish” and non-responsive.

If you suspect this to be the case, try a “hard reset” to clear the memory and start the phone up from scratch. Press and hold the HOME and SLEEP/WAKE buttons simultaneously for about 10 seconds – ignore the “Slide to Power Off” graphic – just keep holding the two buttons until the screen goes totally blank. Wait a few moments, then press the SLEEP/WAKE button for 2 seconds to start your phone up again.

Check the App Store regularly for software updates in case new releases for your installed applications are available. These may fix bugs or performance problems.

19. Charging from a computer via USB? Make sure computer stays on long enough.

Many of us use “Energy Saver” features on our computers to put them to sleep when not in use. But if you’re charging your phone from your computer, you’ll want to make sure your computer stays awake, otherwise you might not be giving your phone enough time to charge up properly!

Check your computer’s Energy Saver settings in Mac System Preferences or Windows Control Panel to ensure it stays awake long enough for phone charging.

20. Get the latest software updates for your iPhone

Apple are continually looking at ways to improve the iPhone 3G’s performance and battery life, and as they find issues relating to this they will put out a software update.  It’s important you download these updates (done through the iTunes sync process), and update the software on your iPhone as it can address important performance and battery-life issues. Apple states the 2.1 software update “significantly improves battery life for most users”.