Ohm's law.
Someone please correct me if I get the details (of the twist) wrong, but this is the general idea.
Ohm's law describes how electrical potential, current, resistance, and power relate.
Electrical Potential (AKA voltage) is measured in Volts (V) and symbolized by V.
Current (aka amperage) is measured in Amperes (A) and symbolized by I.
Resistance is measured in Ohms (greek letter omega, Ω) and symbolized by R.
Power (aka wattage) is measured in Watts (W) and symbolized by P.
There are only 2 equations that matter:
V = I * R
P = I * V
Plus some algebra.
So, the Twist works with V = 3.2 to 4.8. Say it's set to 4.8 V and you're using a 1.5 Ω cartomizer/attomizer/whatever. That means that the carto would be drawing 3.2 A of current……which the twist can't do.
As a safety precaution, it's limited to 2.5A maximum current and something happens to restrict it to that so there's no chance of an over-current fault that might cause the battery to overload/vent/explode.
So, the most you can draw from a 1.5 Ω carto/atty/whatever is V = 2.5 * 1.5 = 3.75 V. And there's no reason to set it higher.
Now, if you really wanted to run your 1.5 Ω carto at 4.8 V, you're getting P = I * V = (V/R) * V = V^2 / R = 15.4 W. That's pretty ridiculous. 10W is where the Kick tops out, so let's use that as an example instead. Working backwards to get the current we need…
P = I * V = I^2 * R
I = (P/R)^(1/2) = sqrt(10/3) = sqrt ( 3.1 ) = 1.76 A
Then, V = I * R = 1.76 * 3 = 5.3.
Well……okay, not quite, because the twist tops out at 4.8. But it's under the current limit and the Twist can actually get pretty close. So what's the most power it can do with different atomizers?
By my calculations, it looks like right around 2.2 Ω is perfect. You can go up to about 10.4 W (4.8 V @ 2.1 A) if it'll actually give you all the voltage (which it won't…but it's close…ish). That's nothing to sneeze at. Everything else has a lower max wattage either because the current limiter kicks in (seems to be around 2.1 A based on pbusardo's nifty chart, not 2.5 A like I assumed) or because the battery can't do a higher voltage.
So…unless I'm missing something, 3.0 Ω is too high…2.2 is about right. And the numbers I'm seeing roughly correlate to what I've been experiencing with the thing……if you assume that the markings on the dial are more like guidelines than actual markings.
Man…that took a while. If only I could find more 2.2 Ω attys. I might end up looking towards something with a higher current limit instead of buying another……but it's not like the thing is bad. It just doesn't like really LR.
