@SirRichardRear good video and good basic explanation. I think a lot of the confusion comes not only from the variation between mechs vs regulated but with mods like the smok alien which displays info kind of funky. It confused me anyway. I have the istick tc100w which is a bit odd in that it's a parallel regulated mod, most are series. The alien being a 220w mod should be series.
For example on my alien right now I'm vaping at 38w and the readings say 3.775v, .352 ohms and 10.72 amps. Going by the math, 38w/3.7v/2 (series)/0.9 (efficiency) = 5.7a (out of available amp limit of a single 18650 - series, double volts, total amps equal amp limit of single battery). In order to get the amps that are displayed on the mod and using the data displayed, 38w/3.775v/0.94 (playing with efficiency #'s and using 93-94% efficiency which is within possibility) = 10.73 to 10.71a which is what's showing on the screen.
The math pretty much works out within reason but examining the display of the alien mod it looks to be using the batteries as parallel rather than series (which we know is wrong if it's a 220w unit). It would be less confusing if the display showed 38w, .352 ohms, 7.55v and 5.3 to 5.4a. Then users would have a better idea of their battery draw I think. I know there's a difference in what's hitting the atomizer vs what's being drained off the batteries but for those looking at the data in terms of their battery drain the info displayed seems a bit back assward.
Unless I'm wrong I think it's safe to say that inverting the values would give a more accurate assessment of the load. Read the voltage display and double it, read the amperage display and halve it. Not on all regulated mods but at least with this one in particular. I've seen quite a few confused questions come up in terms of battery use with this mod in particular as it's been one of the more popular recent mods and personally it had me scratching my head. It's nice to have a display that makes some sort of sense or why have it.