There is a lot of confusion about battery charging such as how long to charge a battery for the first time, how long does a charged battery last for etc. There are various sizes and strengths of e cigarette batteries for example:

650mAh charge = 6-8 hours

900mAh charge = 10-14 hours

1100mAH charge = 18-22 hours

18650mAH charge = 18 = 22 hours

Over a period of months you may find that your lithium ion electronic cigarette battery loses performance and the amount of time between re-charges dwindles. This is natural and you can expect to get around 8 months from a standard e cigarette battery, after this period you should really dispose of it safely and buy a new one.