Absolutely you can!
The Istick display is not "wrong" - just calibrated in mean volts rather than RMS.
RMS is a better way to calibrate a device because it better approximates for an AC waveform what a DC voltage would do.
The Istick will happily maintain a nice, steady power level once you dial in the sweet spot for your setup. The only place you would notice an issue would be if you changed to a coil with a different ohms and expected the VW mode to maintain the same vaping feel. The VW mode should be able to do this on an RMS device - in theory.In practice, you would likely tweak the wattage with a different coil/juice combo anyway, for other reasons.
You just may have to tweak the wattage a bit up or down if you change coils. No big deal.
Best,
Don
I think I need to retract my statement that it is not wrong. It is...
A new issue came to light. The Istick reduces the voltage from the boost circuit by 1 volt from 5.8 to 4.8 at about where the battery shows 2/3 of a charge if a voltage setting of less than or equal to 4.8 volts is selected, apparently as a battery saving measure. The Istick gives no indication that this has happened, since it compensates to maintain a constant voltage to the coil by adjusting to a higher PWM duty cycle to maintain the same mean power to the coil.
However, the user will perceive this as a sudden drop in power when the voltage is reduced. In my case, the drop is about 2.5 watts RMS.
I ran the following graph for just the 2.0 coil setting, with an extra trace showing the change due to the Vmax shift when the battery indicator shows < = 2/3. It shows that the Istick will display a nice-looking continuous wattage and voltage even when the Vmax steps down at 2/3 battery. However, since
the actual user experience is governed by the RMS power rather than the mean power, the user will perceive a sudden drop in power when the battery hits 2/3 and lower.
In my case, I use a BVC coil that reads 1.9 ohms, which is pretty close to this graph. I run it at an Istick displayed wattage of 8.0, which is actually about 12 watts RMS. However, when the battery drops to 2/3 or less, the RMS watts drops to 9.6, although the Istick won't show any change on the display at all - watts or volts.
A 2.5 RMS watt drop would likely be quite noticeable. That is just plain wrong on the part of the designers. Is it a deal breaker for the Istick? Not for me, as long as I'm aware of it. However the user will likely feel the difference even though the display will show absolutely no sign of the sudden shift at 2/3 battery..
It also makes the VW mode less useful, as it is supposed to maintain the watts over any variation in coil resistance by adjusting voltage to maintain the watts. It won't.
I still really like the Istick, even with these flaws. It's easy enough to compensate for the perceived power loss with a few clicks once it kicks in.
This would be quite easy to fix in the firmware by just changing the regulation to RMS from mean. Maybe in v2.
Don