Improve battery life...

[BigDiesel07]

Here’s the deal: even though it is not recommended to fully discharge Li-Ion batteries (as opposed to NiCd batteries), it is advised to do this around every 30-40th cycle (that is approximately 30-40 days or so for most people) in order to recalibrate the metering system on your battery. The principle is simple: you need to drain your battery completely so that the meter would acknowledge a close to 0% and start counting from there. Repeated everyday charging will get this slightly out of accuracy.

The bottom line: completely drain your battery around every 30-40th cycle and do a full recharge with the supplied wall charger while having the device powered off. Keep it charging until you see the fully charged LED notification. You’ve recalibrated your battery and contributed to its longer, healthier life.

Check the full reason out here

Also check this and this for ways to have longer battery life...