Warning and disclosure!:
You might not like the maths. You might not need the maths. Anyway, apropos the premiere of the eLeaf iStick 20W in later September 2014, some people had to stay in touch, again, with the PWM problem.
It appears that the same, more or less, happened with some VAMO and other early VW Chinese mods in 2012/2013..... but eLeaf / iSmoka did not attend the meeting.....
How about the voltage on screen does not reflect the power felt in vaping with an iStick 20W? Because that one uses average volts in its screen, and not Root Mean Squared volts, the ones valid to calculate power with the famous formula:
So, knowing that the output of the iStick 20 W is a PWM (Pulse Width Modulation), seems fair to ask about what is that.....and how to convert to the relevant parameters.