The capacity of a battery is given in mAh. The higher this value, the longer the period till the next charging.
if you are a light smoker (below 10 cigarettes a day), battery of lower capacity may suit: 280 mAh or 650 mAh is recommended
if you are a moderate smoker (10-15 cigarettes a day), 900 mAh capacity is suggested
if you are a strong smoker (more, than a box of cigarettes a day), capacity of 1100 mAh or 1300 mAh will suit you