Spaced coils vs. tight coils resistance

[Arvellon]

Hi,

I purchased an RTA which is single coil, and now all coils I build have high resistance.

My questions:
1. Does a single coil have a higher resistance than dual coil if the coils are the same (same wire, same gauge, same amount of wraps, ...).

2. Would making a spaced coil instead of a tight coil result in a lower resistance?

3. Any other tips/ideas to get a lower resistance coil?

ps. The RTA is the Serpent SMM, I use 23AWG SS317L wire (wire doctor) and my mod is the smok Alien TC

Thanks in advance!

 

[Coastal Cowboy]

1. If you have two identical coils (same wire, number of wraps, inside diameter), the resistance of your build will be exactly one-half of a build made with just one of them. This is because you have doubled the pathway for electrons to flow through the circuit.

2. A spaced coil using a certain total length of wire will have the same resistance as a contact coil made from that same amount of wire. A spaced coil that has the same cylinder length as the contact coil will use less wire and have a lower resistance.

3. Use a larger ID for your coil (go from 2mm to 3mm) and use the same number of wraps. Use fewer wraps. Use a less resistive wire like stainless vs kanthal.

Smok mods do a less than stellar job of temperature control. They can do it, but you're really better off in power mode with Smok.

Try using a twisted or multiwire coil like a Clapton instead of that borderline coathanger wire. Wire gauges thicker than 26awg have a dropoff in flavor production due to lower surface area. The math is worth exploring elsewhere, but a similar diameter wire made from twisting two strands of 28awg or three strands of 30awg improves flavor efficiency in ways that will roll your eyes back in your head.

 

[Sugar_and_Spice]

You may also need thinner wires. 23 AWG is wider than say Awg 26, or 28. What this means is the thinner the wire the less mass you have to heat up. This affords lower ohms to be obtained.

 

[Sugar_and_Spice]

Try using a twisted or multiwire coil like a Clapton instead of that borderline coathanger wire. Wire gauges thicker than 26awg have a dropoff in flavor production due to lower surface area. The math is worth exploring elsewhere, but a similar diameter wire made from twisting two strands of 28awg or three strands of 30awg improves flavor efficiency in ways that will roll your eyes back in your head.

I haven't used the twisted wire yet. What ohms(resistance) can be expected if the total mass is similar to 24 AWG?

 

[Coastal Cowboy]

I haven't used the twisted wire yet. What ohms(resistance) can be expected if the total mass is similar to 24 AWG?

Let's go to the Wire Wizard and see!

Twisted 3x30awg Kanthal:

Single 24awg Kanthal:

I'm not answering your question the way you asked it--you asked to solve for resistance given a certain mass and I solved for mass given resistance. But in order to achieve the same mass as the twisted wire coil, I would have to increase the number of wraps to an infeasible number and it would produce a coil with at least 2.5 Ohms.

What I was trying to do was get the OP to try increasing surface area rather than lowering just resistance because on a regulated mod resistance doesn't matter (except in temperature control). Look at the difference in surface area for the two coils. More surface area means more juice in contact with hot metal, which means more flavor.

 

[Coastal Cowboy]

Oops.

Link to the Wire Wiz:

Wire wizard | Steam Engine | free vaping calculators

 

[Coastal Cowboy]

You may also need thinner wires. 23 AWG is wider than say Awg 26, or 28. What this means is the thinner the wire the less mass you have to heat up. This affords lower ohms to be obtained.

I missed this.

Thinner wire produces higher resistance, even though there is less mass. Thicker wire has more mass, but its wider diameter means there is more room for electrons to flow. It does take less power to heat the thinner wire, though.

This is why higher resistance builds do not always mean you will need less power. Let's say you have two builds made from the same wire. One has a resistance of 0.50 Ohms, the other 1.0 Ohms. It will take significantly more power to heat the 1.0 Ohm build than it will the one at 0.50 Ohms. A power setting that produces decent vapor on the 0.50 Ohm build may not produce any vapor at all from the 1.0 Ohm build.

Let's say you have two builds with equal resistance of 1.0 Ohms but one is made from 30awg (thinner) and the other from 26awg (thicker). It takes less power to heat the 30awg build than the 26awg build. In fact, if you hit the 30awg with the same wattage you use on the 26awg, you stand a good chance of popping the coil through overheating.

 

[Sugar_and_Spice]

Thank you Coastal Cowboy, such a detailed answer. I really appreciate it.

 

[Storm52]

I missed this.

This is why higher resistance builds do not always mean you will need less power. Let's say you have two builds made from the same wire. One has a resistance of 0.50 Ohms, the other 1.0 Ohms. It will take significantly more power to heat the 1.0 Ohm build than it will the one at 0.50 Ohms. A power setting that produces decent vapor on the 0.50 Ohm build may not produce any vapor at all from the 1.0 Ohm build.

I find the reverse is true. I use 1.8Ω coil at 8 watts. If a .5Ω coil is used, I don't get much if any vapor @ 8 watts. I normally have to bump it up to 20+ watts to get a decent vape. Wouldn't a high resistance produce higher temperature at the same power? Isn't the power restricted at higher ohms and doesn't "flow" as quickly? Maybe I'm missing something!

 

[Coastal Cowboy]

I find the reverse is true. I use 1.8Ω coil at 8 watts. If a .5Ω coil is used, I don't get much if any vapor @ 8 watts. I normally have to bump it up to 20+ watts to get a decent vape. Wouldn't a high resistance produce higher temperature at the same power? Isn't the power restricted at higher ohms and doesn't "flow" as quickly? Maybe I'm missing something!

Are you building with the same wire for the 1.8 and 0.5 Ohm coils?

Assuming the same wire, the difference between the two is the mass of metal and their different heat capacities.

Heat capacity is the amount of energy required to increase the temperature of an object by 1 degree. The larger the mass, the higher the heat capacity.

To get a better vape with the higher resistance coil at the same voltage, you would reduce the diameter of the wire, which would reduce mass and reduce heat capacity.

Look at it this way. Put two pots of water on the stove. Put one liter in one pot and two liters in the other. Turn the heat on for both. It will take more time or more heat to make the larger quantity boil. The smaller pot represents the 0.5 Ohm coil of a certain gauge and the larger one represents the 1.8 Ohm coil of that same gauge.

There's more physics involved, too. If you put the heat on a low setting with the two pots, you may eventually get the smaller pot to boil, but the larger pot may not boil at all. That's because the object being heated also dissipates energy into the atmosphere. If it dissipates heat at a rate fast enough to prevent reaching the boiling point, the water simply evaporates.

Same thing with coils in your atomizer. A larger mass may not heat to the desired temperature unless more heat (Wattage) is applied.

 

[sonicbomb]

Regardless of what wattage you are using the goal is the same, maximum surface area and minimum mass.

Understanding the relationship between power and coil resistance | E-Cigarette Forum

 

[Storm52]

Regardless of what wattage you are using the goal is the same, maximum surface area and minimum mass.

Understanding the relationship between power and coil resistance | E-Cigarette Forum

Thank you both. Light bulb, with minimum mass, turned on!

 

[vapdivrr]

Just curious though, why do you want a lower resistance with the 23g wire? Seems 23g at 2.5 or 3mm coil with an average number of wraps will give you a pretty low resistance to start. Are you looking to heat up faster?

Sent from my SCH-I545 using Tapatalk

 

[BrotherBob]

I purchased an RTA which is single coil, and now all coils I build have high resistance.

Welcome and glad you joined.

 

[chellie]

Are you building with the same wire for the 1.8 and 0.5 Ohm coils?

Assuming the same wire, the difference between the two is the mass of metal and their different heat capacities.

Heat capacity is the amount of energy required to increase the temperature of an object by 1 degree. The larger the mass, the higher the heat capacity.

To get a better vape with the higher resistance coil at the same voltage, you would reduce the diameter of the wire, which would reduce mass and reduce heat capacity.

Look at it this way. Put two pots of water on the stove. Put one liter in one pot and two liters in the other. Turn the heat on for both. It will take more time or more heat to make the larger quantity boil. The smaller pot represents the 0.5 Ohm coil of a certain gauge and the larger one represents the 1.8 Ohm coil of that same gauge.

There's more physics involved, too. If you put the heat on a low setting with the two pots, you may eventually get the smaller pot to boil, but the larger pot may not boil at all. That's because the object being heated also dissipates energy into the atmosphere. If it dissipates heat at a rate fast enough to prevent reaching the boiling point, the water simply evaporates.

Same thing with coils in your atomizer. A larger mass may not heat to the desired temperature unless more heat (Wattage) is applied.

That is a great explanation with examples and I understand it and it makes sense. Still, I find the same thing @Storm52 said so I have to think it through. I vape on a .5 coil at 20 watts. If I use a 1.2, for example, I find I have to turn the wattage down and that lower wattage does not give a good vape on the .5 coil. I am guessing that in the example I just gave they were not the same wire