The life of battery depends on the no. life cycles i.e no. of complete charging-discharging cycles, which battery undergoes during its life span. So the key method to increase the battery life is avoiding the unnecessary charging-discharging cycle.
Following are the 6 ways to increase the battery life.

1: In laptops, tone of the most important factors affecting the battery life is the Fan. If there is more dust on the fan it consumes more power and laptop can easily get heated. Keeping the fan clean can boost up the performance.

2:Do not expose the battery to heat. This can include, not using a pillow or blanket or any such things for the under support of laptop, as these can easily block the ventilators and make the fan work more. Its always advisable to use laptop on a hard platform.

3:  You can choose to set laptop to automatically dim the display after few minutes of inactivity and later goto hibernate mode automatically.

4: Avoiding the use of screen savers can help save the power.


5: Keep the brightness low i.e Power Saver Mode(if that is OK for you to work in low brightness) or else you can choose to work in the Balanced Mode.

6: De-fragmentation can also help you because faster the hard drive, lesser its demand for power.

Now, the most important thing. I have seen many people who just remove the battery of laptop and use it directly with help of AC adapter. They do this because it helps reduce the battery wear. Well, surely it reduce the battery wear but what they do not know is that if there is a sudden power cut for few times, it can kill your hard drive forever.

So, my suggestion is to always use the laptop on battery. And make it a practice to always completely charge the battery to 95-100% and charge it again only after a complete discharge i.e 10-15%. Its fine to recharge the battery from half-way if its really necessary but do not do that on regular basis.