Coils for Tanks – FAQ

With some basic math for calculating the resistance, voltage or amps.

Frequently Asked Questions about Atomizer Coils

Answers to Frequently Asked Questions about e-cig coils.What is an e-cig coil?

Coils consist of a wick wrapped in kanthal wire (traditionally, but there are a variety of materials on the market like nickel, titanium and steel) inside of a metal cylinder. One end is threaded (traditionally but changing to threadless) to screw into your tank or clearo and the other has holes to let in e liquid. The wick soaks up the e-juice and when you press the fire button on your e-cig, a current runs through the coil creating heat, which vaporizes the ejuice.

Because the wick slowly loses its absorbancy and the resistance on the wire increases from repeated use, manufacturers recommend replacing coils once per week. While once a week might seem extreme for some, 2 to 3 weeks is the longest you can enjoy a coil before your flavour and vapour decrease, even at lower Watts. With the introduction of ceramic coils, good flavor and vapor production can be expected to at least double that of a metal only coil. The higher the watts or temperature the coil is run at the sooner it will expire.

Although coil replacement can seem like a hassle, it’s a great way to renew and refresh your vape. Manufacturers such as Sense, Horizon, Smoktech and Aspire continue to improve wick absorbency, airflow and temperature control in disposable coils and offer varying resistances and coil configurations that allow you to discover and fine-tune your personal vaping preferences.

Why Do They Rate Coils by Ohms?

By sending current through a wire the amount of resistance in the wire determines how hot the wire will get. Resistance is measured in ohms. The trend in vaping is toward lower “ohm” coils. The less resistance on a wire, the more power is required to create heat.

For a while we stabilized around 2 ohms but in the last couple years the trend has inched ever lower until the term “sub-ohm” was coined to describe coils running below 1 ohm. The lower ohm coils last much longer and provide a full rich vapor. The down side to lower ohms is a greater requirement in watts, so your battery will discharge faster.

We don’t all sub ohm however. Many popular models still come with 1.8 ohm coils and many of us stick right around 1.2 – 1.8 ohm for longer battery life and the flavor/vapor combination we like. Originally all coils used kanthal wire because resistance does not change when kanthal is heated, providing a constant output.

The diameter of the wire affects the final resistance of the coil. The thinner the wire (higher gauge number), the higher the resistance per foot. The thicker the wire (lower gauge number), the lower the resistance.

Nickel 200 is a ferromagnetic, commercially pure (99.6%) Nickel with good mechanical properties over a wide range of temperatures, high ductility, and excellent resistance to many corrosives (in particular hydroxides).
Ni200 has roughly the strength of mild steel when annealed and can provide higher strength levels when in the “as rolled” condition.

Note:

Only use the Nickel coils when using a temperature limiting mod.
Do NOT use Nickel coils on ANY mod other than those with temperature limiting.

 

How do I set my voltage for a coil?

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

note.: This chart works for BDC’s and VV (variable voltage) batteries. For lower ohm vaping you really should have a variable watt mod (VW).

What are Rebuildable Coils?

Rebuildable Atomizers (RBA), Rebuildable Drip Atomizers (RDA) Rebuildable Tank Atomizers (RTA) are subset of e-cig and vaping that presents a more challenging learning curve but many vapers prefer this method. An RBA has a deck with mounting posts. Users either wind their coils (number of wraps determines final resistance) or purchase them separately. The coils are wicked with cotton to adsorb the e-juice and provide an abundant supply to the heated coil.

How are Ohms Calculated?

A lot of posts refer to Ohms Law. Beginners can skip on by, this section deals with the theory behind creating a coil of a predetermined resistance and the number of watts it will take. Here’s a quick summary for your reference.

So, E stands for Voltage of course. What else would it stand for?
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 remembering the formula.

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.
When winding a new hand built coil, the resistance of the final coil will be a factor of the resistance of the metal and the number and size of winds. There are many good tutorials for specific builds.

Watts is Volts x Amps (Watt =E x I)

Coils should be replaced regularly. Once every 2 – 3 weeks is usually sufficient.