Understanding Resistance with Coil Builds...Help?

[Donnie Narco]

I am still trying to wrap my head around (no pun intended) understanding resistances when building coils. I have been building coils for a few months, and for me it seems to be just a straight crap shoot to what I end up with.

I learned to build a 4 wrap quad coil with 28 gauge wire on a 1/8th drill bit and usually end up with .3 ohms...but how?

My questions are:

1) what does it mean to say 3/4 or 4/5 when talking wraps?

2) why is it that I see people making nano quad coils with 24 gauge and something like 12 wraps, yet they can get down to .1 ohms??? (I mean, I tried making a tight 7 wrap quad 28g and ended up with something like .7 ohms...)

3) I understand the basic principles of resistance. The thicker the wire, the less resistance because there is simply more "matter" for the electricity to flow through. But why are mine so much higher in ohms?

4) What are the advantages of using twisted or flat wire over standard Kenthal?


Thanks for anyone who can help me understand all of this. I do appreciate it! You all are great!

 

[sawlight]

1) When you look at a coil from one side you will see 3 wraps, when you look at it from the other side it will show 4 wraps, this is because of the tag ends that you tie to atty posts.

2)Resistance is divided, not added, when coils are placed parallel. If you have two 1 ohm coils, you will end up with a .5 ohm load on the battery. If you have four 2 ohm coils you will end up with a .5 ohm coil also. It's confusing, I know, but resistance does funny things under load.

3) Because you are doing more wraps, most use the heavier wire because it's easier to work with in the smaller coils and takes longer to heat up so it wont burn your juice when doing sub ohm builds. A 5/6 wrap with 32ga gets me around 1.8 ohms, where a 4/5 wrap of 28ga gets me around 1.6 ohms.

4) No idea, never played with it, unless it's easier to use when twisting together to make coils?

 

[Mikey6]

The 3/4 wrap is counted as 3 passes on the leg side and 4 passes on the outside (at least that's how I see it). So if the legs are going the same direction like on an igo, the side towards the post would look like 3 wraps and the side but the cap would be 4 wraps.

24 g wire has a pretty low resistance and using the nano wrap around a paper clip or 20g needle uses very little length of wire, which is where the low ohms comes in. Plus at 4 coils it's only 1/4 of the average resistance, so 4 0.8 ohm coils will result in a 0.2 ohm build.

Your higher ohms may be due to the "large" diameter coils you're building. I have dual 10 wrap micros with 30g Kanthal around a 1/16" bit giving me a 1 ohm build.

Twisted and ribbon coils have more contact area than single strand wraps which is going to give you more heat on the liquid and more Vapor, flavor, and throat hit. You can also run more wraps at the same resistance since there is more material.

Hope this helps a bit and I'm sure someone else will come along with more advanced explanations or tidy up where I was a little unclear.

Sent by thumb smashing my Note II.

 

[Donnie Narco]

So let me see if I get this right. I would have a lower resistance (lower ohms) if I were to build the exact same coil with 24 gauge than 28 gauge, because the 24 has less resistance??

And I know resistance is divided, but I guess what I was trying to ask is how can they use so much wire and get such a low ohm? When I learned, the guy who taught me said that 4/5 wrap was the best way to get down to a .15 ohm (which was as dangerous as I would go with a 30amp efest)....so how do these 11/12 wraps get so low? **Did I just learn incorrectly and I am thinking of resistance backwards, in that of course more wire would equal less resistance, but the way I was taught was that less wire equals less resistance???

 

[sawlight]

So let me see if I get this right. I would have a lower resistance (lower ohms) if I were to build the exact same coil with 24 gauge than 28 gauge, because the 24 has less resistance??

And I know resistance is divided, but I guess what I was trying to ask is how can they use so much wire and get such a low ohm? When I learned, the guy who taught me said that 4/5 wrap was the best way to get down to a .15 ohm (which was as dangerous as I would go with a 30amp efest)....so how do these 11/12 wraps get so low? **Did I just learn incorrectly and I am thinking of resistance backwards, in that of course more wire would equal less resistance, but the way I was taught was that less wire equals less resistance???

It's getting date in the lay and I haven't had much sleep with this storm moving in, so bear with me.
Here's a resistance chart per inch,
26 AWG 0.275 Ω/in
28 AWG 0.439 Ω/in
30 AWG 0.696 Ω/in
32 AWG 1.091 Ω/in
34 AWG 1.758 Ω/in
36 AWG 2.783 Ω/in

From here, Resistance Chart for Kanthal A1 | God of Steam

If there is four coils in the build and each coil is 2 ohms that lowers the total resistance to .5 ohms, if it has two coils at 1 ohm, same thing. These are multi coil builds you are referring to, right?
If not, then they are using the heavier wire, smaller number, larger the wire, the less resistance, thus the more coils needed to get the same resistance.

 

[Donnie Narco]

These are multi coil builds you are referring to, right?
If not, then they are using the heavier wire, smaller number, larger the wire, the less resistance, thus the more coils needed to get the same resistance.

Now this is making sense! Yes, this is what I was thinking, but I just needed some reassurance. Thank you! Go try to get some sleep and prepare for that storm!! Be safe bro!

 

[DasBluCig]

Now this is making sense! Yes, this is what I was thinking, but I just needed some reassurance. Thank you! Go try to get some sleep and prepare for that storm!! Be safe bro!

Think of wire gauge as water pipe....a LARGER pipe offers LESS resistance to water flow, whereas a SMALLER pipe has MORE resistance to flow....as the wire gauge # INCREASES...so does RESISTANCE; thus, a 32 gauge wire offers MORE resistance than a 28 gauge wire....
HTH!
Happy (vaping) Trails!

 

[jersey_emt]

The number of wraps is meaningless. Using the same gauge of wire, I can build a 10-wrap coil that is 2 ohms, another 10-wrap coil that is 1 ohm, and another 10-wrap coil that is 0.5 ohms. The difference would be the coil diameter.

When you use less length of wire, the resistance is lower. It takes a lot less wire for 10 wraps around a paperclip than 10 wraps around a 1/8" bit, so the paperclip coil will have less resistance.

This is true regardless of how many coils you have connected in parallel. A quad-coil build with each coil being 10 wraps around a paperclip will use much less wire than a quad-coil build with each coil being 10 wraps around a 1/8" bit, so it will also have less resistance.

 

[dripdaze]

Hi Donnie. Take a look at the spreadsheet in this thread. You can use it to change various coil parameters and see how it affects resistance: http://www.e-cigarette-forum.com/forum/new-members-forum/506159-kanthal-coil-calculator.html