Keeping an extra battery, charged and handy, is a good plan anytime. Long flights and longer meetings, power blackouts and transit snarls - an extra battery gives you the power to keep on communicating, come what may.
Talk time spent on the phone, signal strength, flashing notification lights, screen time out and charging habits are a few conditions that may contribute towards the operational battery time. Battery Li-ion high performance, no memory effect and fitted with an integrated protection against overloads and overvoltages.
Full battery performance is achieved only after 2-3 charging and discharging cycles have been completed. It is recommended to fully drain and fully charge the battery especially during the first 3 charging and discharging cycles, doing so may greatly improve the overall life of the battery.