Ohms Law Equation / Power Equation

A fully charged 'vape safe' battery has a maximum capacity of 4.17v and a minimum capacity of 3.02v



  • The ‘I’ stands for current in Amps.
  • The ‘E’ stands for Voltage.
  • The ‘R’ stands for resistance in Ohms.
  • The 'P' stands for Watts.

A fully and on the right way charged ‘vape safe’ battery (in this example we will be using the Sony VTC 6 3120 mAh) has a maximum capacity of 4.17v. So if we use a coil or coils (that after reading from a resistance meter) measure 0.5 Ohms, de following formula will stand:

  • 4.17v (U) / 0.5 Ohm (R) = 8.34 Amps (I).

This battery has a discharge capacity of 30 Amps, which means you are in the safe zone, to be using these coils.

To test with the minimum Ohms, we turn the formula around:

  • 4.17v (U) / 25 Amps (I) = 0.17 Ohm (R)

The Sony VTC6 has a maximum discharge capacity of 30A, but you will never use the full 30A in the formula. You will hold 5A to ‘yourself’. So in this case we use 25A in the formula. We do this to stay in the safe zone of the battery. DO NOT GO AND PLAY AROUND WITH THIS.




There are different types of batteries:

  • 18650
    • 18650 IMR (I = Lithium, M = Manganese, R = Round shape) 
    • 18650 INR (I = Lithium, N = Nickel, R = Round shape)
    • 18650 ICR (I = Lithium, C = Cobalt, R = Round shape) contains an extra circuit board (PTC) for protection, this controls the current output of the battery. Do not use these for vaping!
  • 20700
  • 21700

The first two numbers represent the diameter of the battery, the second two numbers represent the height of the battery and the last number represents the shape of the battery. For example: "18" in diameter, "65" in height, and "0" the cylindrical shape of the battery.


Series arrangement

  • Also known as 'stacked'.
  • One 'after' the other ( - + )( - +).
  • Battery Voltage will double.
  • mAh stay the same (milliamp-hour).
  • Always pair or 'marry' your batteries.


Parallel arrangement

  • Batteries faced in the same direction.
  • Batteries act as one larger battery.
  • Voltage stays the same.
  • Batteries will share their Amp limit (1.5 x the current limit).
  • Double the battery life.
  • Always pair or 'marry' your batteries.




  • Kanthal contains mostly Iron, 20 - 30% Chromium, 4 - 7.5% Aluminium. Unlike alternative types of metal such as NiChrome, Kanthal is durable enough to withstand the temperatures needed, but flexible and cheap enough to be practical.
  • NiChrome80 contains 80% Nickel and 20% Chromium.
  • Kanthal, Stainless Steel and NiChrome80 are the most popular choice for making coils.

Kanthal (A1), NiChrome (Ni80 or NiCr80), Nickel (Ni-200), Stainless Steel (SS with 304, 316L or 317L) and Titanium are the most common types of wire used for building coils. Kanthal and Stainless Steel coils are both safe and easy to use, and Stainless Steel coils are known to be more durable than the rest while also providing exceptional flavor and cloud production.

Kanthal has the slowest ramp-up time of all common types of wire, but it’s also very forgiving. When you’re just getting started, you don’t necessarily want your coils to heat up in a split second, and thanks to how durable and malleable it is, it’s easy to twist and braid without breaking. It’s cheap as it is, but even more so if you buy it on a spool.

Stainless steel, on the other hand, heats up faster, lasts longer and delivers better flavor than Kanthal. While there’s nothing wrong with using Nickel, NiChrome or Titanium coils, just be sure you know what you’re doing first. For example, Nickel coils can actually melt if the Wattage is set too high.

One last thing:
  • The thinner the wire (the higher the gauge / AWG) the higher the resistance in Ohms.
  • The thicker the wire (the lower the gauge / AWG) the lower the resistance in Ohms.


Some tips:

  • 0.3mm (28g) – 0.4mm (26g) – Best suited for Rebuildable tanks with a small build deck. This will result in coils with a higher resistance in Ohms, between 0.6 and 1.6 Ohm.
  • 0.5mm (24g) – Beste allround wire for Dripper with a middle large build deck. This will result in coils with a resistance in Ohms, between 0.2 and 0.7 Ohms.
  • 0.6mm (22g) – 0.8mm (20g) – This wire is suited for extra low resistance coils for Dripper with a large build deck. The use of this wire will result is coils with a resistance between 0.1 and 0.3 Ohms.



  • The less revolutions, the lesser the resistance in Ohms.


How to count:
  • If the legs of the coil go in the same direction:
    • From the first post to the first quarter bend in the coil is 0.5 revolutions.
    • From the last quarter bend in the coil to the second / last post is 0.5 revolutions.
    • All revolutions in between are counted as 1 per revolution.


Number of coils VS. Ohms:

In this example we will use one pre-made coil with a resistance of 0.45 Ohms. Number of revolutions in the coils described below, stay the same.

  • If you would use just the one coil, the resistence would not change and be 0.45 Ohms.
  • If you would use two of the same coils, this will cut the resistance in half. Together they now have a resistance of 0.45 / 2 = 0.225 Ohms.
  • If you would use three of the same coils, the resistance will be divided by three. So 0.45 / 3 = 0.15 Ohms.
  • If you would use four of the same coils, just a quarter of the resistance will remain. So 0.45 / 4 = 0.1125 Ohms.



More resistance/Ohms in Coils

  • Longer battery life
  • Atomizers last longer
  • Subtle flavor (depands on your e-juice)
  • Vapor is cooler (temperature)
  • E-juice lasts longer
  • Dry hit less likely to happen
  • Less dense clouds


Less resistance/Ohms in Coils

  • Shorter battery life
  • Atomizers don’t last very long
  • Flavor increases (depands on your atomizer)
  • Vapor is slightly warmer (temperature)
  • E-juice runs pretty quickly
  • Bigger chance of a dry hit
  • Dense clouds