Form what I know about Lithium-ion batteries draining them is not a good idea. I am under the impression that most if not all e-cigs are Li-ion.
You see the idea of draining a battery is because of NiCd. This type of battery outputs a good voltage all the way up till it is almost dead. This makes it work well for say a drill. NiCd has a problem of growing air bubbles on the plate in the battery if not fully drained and charged each time. This would lower the surface area on the plate and lower the overall power of the battery.
Li-ion batteries age differently. They age at about the same rate each year. It does not matter much if you use it allot or none at all. The loss of power over time is about the same. What does age the battery is:
Draining the battery below a certain voltage (too far)
Heat
Overcharging
From what I understand a Li-ion bat likes to be charged as much as possible at very small amounts to keep it toped up.
You see the idea of draining a battery is because of NiCd. This type of battery outputs a good voltage all the way up till it is almost dead. This makes it work well for say a drill. NiCd has a problem of growing air bubbles on the plate in the battery if not fully drained and charged each time. This would lower the surface area on the plate and lower the overall power of the battery.
Li-ion batteries age differently. They age at about the same rate each year. It does not matter much if you use it allot or none at all. The loss of power over time is about the same. What does age the battery is:
Draining the battery below a certain voltage (too far)
Heat
Overcharging
From what I understand a Li-ion bat likes to be charged as much as possible at very small amounts to keep it toped up.