eCigarette Coils – A Primer on the Electronics

Voltage, Resistance and Atomizer Coils

Just a quick summary of Voltage Rules of Thumb for those of you using Variable Voltage batteries
such as the Vision Spinner. When you order your coils you are asked what resistance you would like. This will make a difference in what power you have to provide the coil….and that’s where it gets as clear as a heavy vape.

If you just want a rule of thumb as to what voltage to set your battery you can use this table:
ed. note.: It’s been about a week since I posted this and I can see some problems with this chart. For one thing, this  only applies to dual coils. For another, I find the voltages high and I actually run a step down from the recommended setting, at least until my coil gets old.When in doubt, start with a lower voltage.

Coil Resistance ΩVoltage
1.7 – 1.92.1 – 3.4 V
2.1 – 2.33.5 – 3.8 V
2.4 – 2.63.9 – 4.2 V
2.6 – 3.04.3 – 4.7 V

A lot of posts refer to Ohms Law. There’s a lot of math in here so I’m going to start by just saying: you don’t need to remember all this. It’s here for background purposes. If you know how something works it’s sometimes easier to maintain when you’ve got an idea of the basic priciples. However, I’d recommend just scanning it until you’re ready to start rebuilding your own.

So, E stands for Voltage of course. What else would it stand for?
I stands for current which is measured in amps.
R actually stands for resistance and is measured in ohms and has the symbol Ω

The LAW by which all our calculations are made states that the amount of current through the coil is directly proportional to the voltage sent across it. This is expressed in the formula:

I=E/R 

If you take out the I from the triangle below, E/R remains. Similarly, if you take out the E you are left with I times R. It’s a handy way to avoid the algebra.

So, what are the relationships?

  • If we hold Voltage (E) constant, changes in current and resistance are inverse (one goes up if the other goes down)
  • If resistance (R) is constant (no change), an increase in either current (I) or Voltage (E) will result in an increase in the other
  • If Current (I) is constant, voltage and resistance will rise and fall together as it does with constant Resistance
Using the “rule of thumb” table I started with, if I have a 2 ohm coil and RAISE the voltage past the recommended 3.5 – 3.8, to say 4.2, since the coil is fixed at 2.0 (I=E/R is I=3.6/2=1.8 amps current at 3.6 volts and 4.2/2=2.1 amps at 4.2 volts, thus putting a lot more strain on your wire coil and may result in that horrible burning taste.

So what happens when you turn up the Volts?

You basically create more heat on the kanthal wire which vaporizes more e juice per second.So that’s what you’re doing when you turn the dial up or down on your variable voltage e cig battery.

But what about VW?

A Watt is a Volt(Amp) Watt =EI
Luckily for us, once we started demanding more variability in our power the manufacturers responded with variable wattage batteries soon after.
The VW batteries save you doing the math! Their circuits sense the resistance of the coil and adjust power to it accordingly. Less chance of overpowering your coil.

Summary

Depending on the type and style of your e cigarette you will need to replace the atomizer coils every 2 – 3 weeks. Vaping at higher volts or watts is a little more expensive because:
  • coils wear out faster
  • wicks are placed under more stress
  • more e juice is used (ie. bigger clouds of vape!)
  • battery will run down sooner