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 battery charge = 6-8 hours
900mAH battery charge = 10-14 hours
1100mAH battery charge = 18-22 hours
18650mAH battery 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.