The relationship between resistance, voltage and power

[Eilrymist]

Hello,

Disclaimer: I am not a smoker, my boyfriend is. I am just an overly enthusiastic chemical engineering major who's learning how to make (not terrible tasting) tobacco flavored ejuices and now rebuilding coils.

The main thing I want to know is a deeper understanding between the resistance, voltage, and power and how it effects the juice. Also, how the juice is exactly being vaporized.

So far, I am just applying some basic physics, but if I am wrong please let me know!

For rebuilding coils:

Essentially, I see that there is a wire of a certain resistance wound around a wicking material, such as cotton or silica. I will learn about the differences in material properties later once I understand the mechanism. Now, is this wire acting as a inductor? I doubt it is acting as a transistor or solenoid because we are not stepping up or down the voltage or wrapping it around a magnetic field inducing material. The inductor will resist the current flowing from the battery, which is AC current, and induce a voltage in a direction dictated by Lenz's law. In an ideal word, conductors would not dissapate any heat. However, is this excess heat what is responsible for vaporizing the ejuice? If so, is the purpose of the wick to pull in the ejuice to be vaporized by the inductor coil?

Then it comes down to battery voltage. The higher the voltage, the more power. So the more heat? My question also leads to as why rebuilt coils can be used around 1.8 or 1.1 ohms and stock coils are 2.2 or 2.5 ohms (in general that's the number I'm seeing). My boyfriend smokes dark tobacco juices and uses 2.5 ohms stock coils on his kanger protank 2. Why are people building coils with lower resistances and still work fine but dropping resistance in stock coils makes it vape worse?

Next would be why are wicks cut quite short around the ends? Would it make much difference if the wicks were left longer? Why are some cartomizers sold with short and with long wicks? Pros and cons?

I'm sorry if I'm completely off or I confused anyone with my post! Thanks!

 

[Hoosier]

The coil is a resister. Completely linear and simple DC math.
V=IR Voltage equals the product of current (amps) and resistance (Ohms). Algebra applies so I=V/R.

Power is a measure of work and the coil's work is evaporating juice and it's simply measured in Watts. W=VI. Power in watts is equal to the product of current and voltage. Algebra applies so W=V*V/R. Lower resistance means higher power. Higher voltage means higher power.

Now there is a balancing act with heat, air flow, and speed of wicking. If the wicking is too slow for the power, then the coil runs dry and gets very hot due to the lack of liquid evaporating keeping it cool and that tastes terrible. With a quick enough wick and plenty of power, without enough air flow to move the vapor out, the vapor gets very hot. (I tend to like a very warm vape, so I usually go for a tight draw.)

Wick length may or may not matter. I don't know the specifics of the air flow of your equipment and have no idea if longer wicks could interfere with the air flow. If they don't then longer wicks are seldom and issue.

Also, cotton burns. Silica does not. Cotton wicks quicker.

The different resistance coils, wicks, voltages, and devices are there so folks can tailor their vape to match what they want. My sister is happy with boge cartomizers on her eGo Twists. My oldest son like his Pro Tanks on a Vamo. I use rebuildable dripping atomizers on a Provari or a huge mechanical with a huge area for dripping. We all have exactly what we like.

 

[BeRight]

The coil is a resister. Completely linear and simple DC math.
V=IR Voltage equals the product of current (amps) and resistance (Ohms). Algebra applies so I=V/R.

Power is a measure of work and the coil's work is evaporating juice and it's simply measured in Watts. W=VI. Power in watts is equal to the product of current and voltage. Algebra applies so W=V*V/R. Lower resistance means higher power. Higher voltage means higher power.

Now there is a balancing act with heat, air flow, and speed of wicking. If the wicking is too slow for the power, then the coil runs dry and gets very hot due to the lack of liquid evaporating keeping it cool and that tastes terrible. With a quick enough wick and plenty of power, without enough air flow to move the vapor out, the vapor gets very hot. (I tend to like a very warm vape, so I usually go for a tight draw.)

Wick length may or may not matter. I don't know the specifics of the air flow of your equipment and have no idea if longer wicks could interfere with the air flow. If they don't then longer wicks are seldom and issue.

Also, cotton burns. Silica does not. Cotton wicks quicker.

The different resistance coils, wicks, voltages, and devices are there so folks can tailor their vape to match what they want. My sister is happy with boge cartomizers on her eGo Twists. My oldest son like his Pro Tanks on a Vamo. I use rebuildable dripping atomizers on a Provari or a huge mechanical with a huge area for dripping. We all have exactly what we like.

Well said, IMHO I would only add that using a variable wattage device the resistance of the coil doesn't make allot of difference (within reasonable coil resistances) since constant power is applied by the vaping power delivery system.

 

[steved5600]

Here is a pic that depicts ohms. voltage and current.
You can calculate wattage by Voltage squared divided by Resistance. In a VW mod you don't have to worry about that if you keep the resistance with in its operating range. I would add that Resistance does make a change in the vape depending on how you accomplish that change. If you rebuild and use a bigger wire than before you will have a longer coil and that will effect your vaper output. Microcoils are an example of that. But wattage remains the same.

 

[DavidOck]

The wicks on bottom coil units are kept short - about flush with the "washer" looking part of the base - to keep them from getting caught in the threads when the topper is assembled.

Top coil clearos use long wicks so they can reach the bottom of the topper to, well, wick up the juice.

There are some slight variations in the vape between top and bottom coil units, and only trying both will determine which you prefer.

Commercial coils for the PT run as low as 1.8, maybe 1.5. With a fixed voltage source, you need to find the value coil that gives the vape you like. With a variable power source - VV or VW - you can control the power delivered, and adjust to different value coils, so it's not as critical an issue.

Batteries provide DC (although variable voltage/wattage ones will generally pulse it to control), so inductance is not a factor. (Nor is capacitance, of course.)