Variable Wattage and Sub Ohming


I wanted to take a second to talk about sub ohming on variable wattage devices and why in most cases, it really does not matter. As a hardcore variable and DNA user I get asked on a regular how low of an ohm can you build on the DNA, how low on the SX, and so and on. I am here to talk about why it does not really matter how low it can go.

Wattage is Voltage squared divided by resistance.  Or W = V2 / R

So in terms of a mech, or a variable voltage powered device, the resistance matter because this calculation will give you the power output or watts. Lets do an example in terms of a mech mod, firing at 4 volts with a .8 ohm coil on it. Written out that looks like this:

W = 42 / .8

In this calculation output power = 20 watts.

So now you take that same atomizer and put it on a DNA or SX mod and set it to 15 watts. In this case the DNA chip is doing a different calculation, one that looks like this:

V = (W x R)2

So lets assume that you set the variable wattage device to 15 watts, lets look at those numbers:

V=(15 x .8)2

In this case voltage or V equals roughly  3.5 volts

Now if we crank that wattage up to 20 on the device, then the voltage will be adjusted to 4 volts.

How far sub ohm you can go on a variable wattage device makes very little difference in how it vapes, as instead of you adjusting resistance for desired power, it adjusts voltage for the power you tell it. In fact with my builds I have actually found sub ohming to produce a lower vape quality due to using less wraps and having less surface area saturated.

Remember there are a whole lot of great ohm calculators out there as well to help you dial in what you need. This one is my preferred.

Hopefully this clears up some of the differences between variable power (wattage) devices and variable voltage or mechanical. If you have any questions or comments feel free to sound off below.


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Understudy77 is an avid regulated and box mod supporter, the resident high horse on The Plumes of Hazard, a blogger at The Ohm Page, and the guy who doesn't actually run Maryland Vapers.