HOW TO EXTEND LAPTOP BATTERY LIFE

There are a few steps you can take to stretch out the available electrons in your
battery thereby extending your laptop's battery life.
ADJUST YOUR POWER SETTINGS
To take advantage of the power-saving features that the laptop's manufacturer has built into your
laptop, you'll want to consult your user manual, as they vary from one machine to another. Meanwhile, you can also give your laptop's battery life a significant boost by tweaking the power options in your operating system.
THIS IS THE METHOD:
Windows Vista and 7 gives you control of how your
laptop manages power by bundling various  hardware and system settings into three default power-plan options: 
1. Balanced.
2. Power saver.
3. High performance.
Balanced 
This offers full performance when you need it, but conserves power when your laptop is idle.
Power saver
This provides the biggest boost for extending battery life, but results in lower performance.
High performance
This maximizes system performance at the expense of battery life.

Switching between plans is a simple two-step process:
1. Click on the battery meter icon, located in the notification area on the Windows taskbar.
2. Select one of the three default power plans: Balanced, Power saver. or High performance.
 If you are seeing just only two power plans after clicking the battery mater, click on 'more power options' so as to locate the third and click on the desired plan. 
For Windows XP 
Windows XP offers two power schemes designed for laptops and other portable PCs:
1. The Portable/Laptop power scheme
2. The Max Battery power scheme
The Portable/Laptop power scheme 
This minimizes power use to conserve battery life, but adjusts as your processing needs change so system speed isn't sacrificed.
The Max Battery power scheme  
This also minimizes power usage but doesn't adjust to changing processing demands. This setting is meant for situations requiring minimal processing, such as reading documents or taking notes.
To switch from the Portable/Laptop power scheme to Max Battery:
1. Click Start Menu, and then click Control Panel.
2. In Control Panel, verify that you're in Category view, and then click Performance and Maintenance.
3. In the Performance and Maintenance window, click Power Options.
4. On the Power Schemes tab of the Power Options Properties dialog box, click the arrow under Power Schemes, and then click Max Battery.
5. Click OK.
Care and maintenance of your battery
There are a few best practices that can help in preserving your laptop's battery life which includes:
- Defrag your hard drive regularly so it runs efficiently.
- Clean your battery contacts with rubbing alcohol periodically.
- Use Hibernate mode rather than Standby mode. 
- Keep your laptop battery out of extreme heat.
- Clean the battery with dry cloth, especially at the metal connectors.
- When plugged in to the AC outlet for a long period of time, Take out the battery from the system.
- Fully discharge the battery once a month by unplugging the AC power cord. After
that, charge it again completely.