How to Make Your Cell Phone Battery Last Longer
While many of us now use mobile phones instead of land-line phones in our homes, these mobile phones come with Lithium Batteries which require some maintenance as long as they are used.
Method One
Increasing the Time between Charges
1
Turn the phone off.
Note: only do this if it's going to be for several hours; turning a phone on/off actually uses a massive amount of power itself. This will probably be the most effective and simple way of conserving your battery’s power. Why? This will help conserve energy and also charge your phone. If you don't plan on answering the phone while you're sleeping or after business hours, just turn it off. Do the same if you are in an area with no reception (such as a subway or remote area, since constantly searching for service depletes the battery fairly quickly.) Some phones have an automatic power save feature, but it takes about 30 minutes with no service to kick in. By then, much battery power has been used. If you don't need to receive or make calls but are using a smartphone as a PDA, disable the phone functionality (flight mode).
2
Stop searching for a signal.When you are in an area with poor or no signal, your phone will constantly look for a better connection, and will use up all your power doing so. This is easily understood if you have ever forgotten to turn off your phone on a flight. The best way to ensure longer battery life is to make sure you have a great signal where you use your phone. If you don't have a perfect signal, get a cell phone repeater which will amplify the signal to provide near perfect reception anywhere.
3
Do not follow the method of full charge and full discharge.Avoid letting your cell phone's battery run all the way down. Unlike nickel-based batteries (such as the NiCd or NiMH rechargeable AA batteries seen in most supermarkets), lithium-based batteries are designed to be charged early and often, and letting them get too low can damage the battery.
[1]With Lithium batteries, doing shallow discharges and frequent charging prolongs battery life.
4
Switch the vibrate function off on your phone, using just the ring tone.The vibrate function uses additional battery power. Keep the ring tone volume as low as possible.
5
Turn off your phone's back light.The back light is what makes the phone easier to read in bright light or outside. However, the light also uses battery power. If you can get by without it, your battery will last longer. If you have to use the back light, many phones will let you set the amount of time to leave the back light on. Shorten that amount of time. Usually, one or two seconds will be sufficient. Some phones have an ambient light sensor, which can turn off the back light in bright conditions and enable it in darker ones.
6
Avoid using unnecessary features.If you know it will be a while before your phone’s next charge, don’t use the camera or connect to the Internet. Flash photography can drain your battery especially quickly.
7
Keep calls short.This is obvious, but how many times have you heard someone on their mobile phone say, "I think my battery’s dying," and then continue their conversation for several minutes? Sometimes, the dying battery is just an excuse to get off the phone (and a good one, at that), but if you really need to conserve the battery, limit your talk time.
8
Turn off Bluetooth.It will drain your battery very quickly.
9
Same goes for WIFI, GPS, and infrared capabilities, if your phone has these features built in.Keep them off except when you need them.
10
Turn the brightness of the display to the lowest setting possible.
11
Use GSM rather than 3G - Using your phone in 3G / Dual Mode will drain the battery quicker than if you just use GSM mode - have a look at your phones spec and you'll see it will quote two different battery life times - normally 50% more for pure GSM use.
12
With a smartphone, avoid using moving or animated pictures or videos for your background.
Animated backgrounds will drain the battery faster.
13
Use a black background whenever possible.AMOLED screens use a lot less power displaying black instead of white
[1]. When web browsing use sites like Blackl
[2]that display a black Google background instead of white.

Source: www.nct.com.ng/forum/make-your-phone-battery-last-longer-method-1_321_p1.html