Dual coil ampere calculations

[qfivenine]

When doing single coils, I calculate the minimum possible resistance with the formula R = E / I. Doing it with the maximum of 4.2 volts that my mechanical/battery can provide. Of course, I don't push it to that resistance, I am happy with around 0.8-1.0 ohms.

What is the formula for dual coils, though? I understand that to achieve a dual coil 1.0 ohm coil I have to build two 2.0 ohm coils in the build. How to calculate the amperage that the battery has to provide? Does that formula change when doing single/dual coils?

Thanks a lot.

 

[eda123]

Use the effective resistance seen by the battery.

You can use the same formula, but you get the total resistance seen. Then you have to make two parallel resistors that combine and give that value.

In your above example, if you calculated you want 1ohm, then yes, you need 2X that value for two coils in parallel.

 

[dripdaze]

Adding a coil results in halving the resistance(ohms) which doubles the current(amps).

 

[eda123]

Adding a coil results in halving the resistance(ohms) which doubles the current(amps).

Only if the coils are the same resistance, in case it wasnt clear for the OP.

 

[dripdaze]

Only if the coils are the same resistance, in case it wasnt clear for the OP.

Good catch. Thanks.

 

[qfivenine]

So, I = E / R equals to 4.2 amps at a single coil 1.0 ohm with a freshly charged battery. Does that mean that for a 1.0 ohm dual coil (2x 2.0 ohm coils) the current is 8.4 amps?

 

[eda123]

No. Its still 4.2 amps. 2.1 amps for each individual coil.

This is why when you run dual coils, you need to crank up your voltage. If you set a 1ohm dual coil to the same level as a 1ohm single coil, you will be underfiring.

 

[qfivenine]

Thanks, now I got it. So to maintain consistency in my vape, should I when attempting a dual coil halve the target resistance? I usually vape around 0.8-1.0 ohm single coils on my mechanical, should I just do a 0.5 ohms dual coil? My battery could handle it: Sony Konion US18650VTC4 2100 mAh.