Dim your screen
The biggest power draw in any laptop is the LCD screen. You will be surprised by the amount of extra battery time you can get by making an adjustment here. Most laptops will have set of brightness up and down buttons (usually with a picture of the sun on them) among the function keys at the top of the keyboard. Holding down the <Fn> key and hitting one of these buttons will let you adjust the brightness of the LCD backlight. Set the display as dim as is comfortable and your battery will last longer.
Get a bigger battery
While this option isn’t available for all models, many laptops will accept an extended life battery pack. If your laptop came standard with a 6-cell battery, you might be able to get a 9 or even 12-cell pack for it. Larger batter = longer life. This will add some weight and may not seat flush with the back of the laptop, but if you need more time, this is the most potent option. In addition, some laptops may have a combo slot where a second battery can be installed instead of a CD or DVD drive. Not many models offer this, but it is worth checking into.
Upgrade to an SSD
Screaming performance is not the only benefit of having a solid state hard drive. While these are still expensive in terms of cost per gigabyte, they can boost your battery efficiency as well. No moving parts means they don’t need as much power.
Adjust your power settings
Many manufacturers include power saving modes that will automatically reduce energy usage when the laptop is not plugged in. If not, Windows has its own. You can have the laptop dim the screen, power down the hard drive, throttle the CPU, or turn the screen off after a period of inactivity. You can also have the system go to suspend or hibernation mode if it hasn’t been used for more than a few minutes.
Turn off your wifi
If you are not using the internet or any devices over your network, turning off the wireless radios will also help you gain time. Most laptops will have either a small slider switch on the front or side of the unit, or a button above the keyboard for this. Some may have a <Fn> button similar to the brightness control. If not, you can always disable the wireless network adapter in the Network and Sharing center in Windows 7 or Vista or in the View Network Adapters screen in XP.
Cycle your battery
While the current generation of lithium ion batteries doesn’t develop a “memory” like the old NiCad models did, you can still lose some life after many partial charge/discharge cycles. Once a month, let you battery run all the way down until the system shuts down and you may regain some life from an older battery.
Regardless of what kind of laptop you have, you should be able to squeeze some extra time out of it if you use one or more of these suggestions. If your battery is 1.5 – 2 years old, it is normal for the life to be reduced to some extent and may need to be replaced in extreme short life cases.