Tips to save iPhone battery life
1. If you are on IPhone OS 3.0 and have push notifications turned on (for instant messengers like AOL or eBuddy), then turning them off would help preserve battery life.
2. Turn off 3G if your operator does not support 3G. This will avoid unnecessary searching of a 3G signal. This can be done from Settings >> General >> Network
3. Keep wifi off when not in use, to avoid continuous scanning of wifi signal at all times. This can be done from Settings >> Wifi. If you have a jailbroken iPhone with Cydia installed use SBSettings to quickly toggle services like 3G, Wifi and Location Services.
4. Similar to wifi turn off Location services (from Settings >> General >> Location services). This will help conserve battery power when you do not need GPS services.Again SBSettings can come of great help here.
5. Turn off Push notifications on your email, and turn it to manual delivery option or to an option so that your email is retrieved in fixed time intervals. This can be done from Settings >> Mail, Contacts, Calendars >> Fetch New Data. In the same options you could choose Advanced and configure specific email retrieval options for different email accounts (eg your work email may require a more frequent retreival interval than your personal gmail/yahoo account).
6. Reduce screen brightness (from Settings >> Brightness). This again can be managed from SBSettings.
7. When clicking on the Home button not all apps actually close, and some continue to run in the background, and keep consuming your battery juice. Again SBSettings comes to your rescue which comes with a process explorer which you can use to kill apps you do not want running.
Hope the above tips help you conserve battery life. I have found significant savings in battery life (my battery lasts 3-3.5 days easily with normal use of internet, emailing, sms and voice calls).
Have attached a picture of SBSettings, so that first time users can get a feel of what it looks like.
