A few abbreviations will be used in the article (no knowledge of electricity is necessary): 

  • Volts (V): Unit of measurement of the voltage of an electric current
  • Watts (W): Unit of power measurement
  • Amperes (A): Unit of measurement of intensity
  • Ohm ( Ω): Unit of resistance measurement

Variable Watts

The power of an electronic cigarette is expressed in Watts and can be set in “Power” or Variable Watts mode. It must be adapted to the value of the resistor inserted in the clearomiser.

The value of electronic cigarette resistors generally oscillates between 0.1 and 2.5 ohm. It is this value that will determine the power range that can be used with the resistance in question. For its part, the voltage adapts to the selected power.

Step 1 – Know the value of your resistance

If you already know the value of your resistance, you can directly go to step 2!

If you do not know the value of your resistor, 2 solutions:

Look directly at your resistance:

The resistor value is indicated in Ohms and is usually written on the resistor itself. For example, for resistance of 1.5 ohms, it will be written: 1.5 ‎Ω. It is even common for the  power range to  be directly written on the resistance, as here:

Watch on the box display:

The majority of boxes have a display screen on which 3 primary information appears:

  • The  power  used
  • Remaining battery  life
  • The value of the  resistor  inserted in the clearomizer

If you don’t have spare resistors or don’t want to bother removing the resistor from your clearomiser, you can find the value of your resistor directly on the screen of your box.

Step 2 – Transfer the resistance value to the table below:

Now that you know the value of your resistance, you will be able to define the best setting for your e-cigarette. If each resistance model is different, we can define typical power ranges according to the value of the resistance.

Two things can be noticed. First, the wattage increases as the resistance decrease. Then, we can notice that the adjustment of the W is not done in a precise way, it shows a  range of use. It is then necessary to test the different values ​​of this power range to achieve the feeling of vape that one is looking for.

It is possible to vape outside this power range, but it still represents a risk.

Power with a value lower than the minimum value of the range will make your resistance less reactive. You will therefore obtain an inefficient vape, with a low volume of vapour and the risk of e-liquid leaking with projections in your mouth.

Conversely, a power higher than the maximum power defined by the range risks wearing out your resistance more quickly due to too rapid heating. You then risk burning the cotton of your resistance and thus obtaining a dry hit.

To go further: in search of the “Sweet Spot”

Sweet Spot is the ideal setting to use with resistance. This makes it possible to obtain a qualitative vape, with perfectly restored flavours. Mathematically, the  Sweet Spot can be defined using Ohm’s Law, which allows an optimal voltage to be applied to a resistor. It is then necessary to select the power relative to this voltage to find the ideal setting. Generally, the voltage in volts of an electronic cigarette oscillates between 3.3 and 6V, with an average voltage of 3.7 V for most models.

For example, if you have a coil with a value of 0.7 ohms, your Sweet Spot is between 16 and 50W. For a voltage of 3.7V, your Sweet Spot should be at 20W.

These values ​​are established using the formula of  Ohm’s Law:  U = R I  (with U = Voltage, R = Resistance, I = Current)

This law can also be interpreted according to the power (P):  P = U (U/R)