Coil surface area vs. ohms

[vapeasy]

Hey everyone, I bought these "goonk" pre-wrapped coils off fasttech a while ago and I am using them in my vivinova 3.5ml.

They work pretty decent but I can't seem to get a decent enough vape off of them for me. I like my vape production on the warm side and it's coming through around room temperature (bleh).

I was thinking I could help the production of the vape by taking a wrap off ( from a 8/7 to a 7/6) to get lower ohms but then I would also lose some surface area (SA) for vaporization. Would the loss of surface area matter that much for vapor production?


Ex:

- 8/7 (+SA) wrap at 2.0 ohm
-Or-
- 7/6 (-SA) wrap at lower ohm ( 1.9-8?)

So... More SA but more ohms, or less SA but less ohms. What's your thought / experience on which wrap would give me a better vape? Any other tips or suggestions would be greatly appreciated.

And on a side note, if I were to take a wrap off, around what ohm mark would I reach?

Battery info: Efest 1100 mah IMR18490

 

[Ryedan]

Yup, shortening the coil wire length by taking a coil off is fine. It will lower the resistance by the ratio of the length you remove divided by the original length. I would not worry about the reduction in surface area. If the coil surface area goes too low compared to the power you apply, it will start giving you burnt hits.

If you could increase the voltage or watts of your PV you would get a warmer vape also.

 

[minimalsaint]

However, if those are non-resistance + resistance + non-resistance wire, taking a wrap off won't help, because the resistance of the coil is set by the length of resistance wire.
Just a thought...

 

[dice57]

Do yourself a favor and learn how to build your own coils. Then you can tweak it to you hearts content to optimize your atomizer. Most prebuilt coils are a joke IMHO.

 

[VapoJoe86]

I'm with dice on this one- learn to build your own coils. You won't regret it and it will save you money. That being said, IMO I find that surface area doesn't greatly affect the vaping experience. I've wrapped micro coils with as few as 3 wraps and still gotten a great vape.

 

[vapeasy]

Thanks for the advice, I will try taking some wraps off. I also would like to build my own but I can't seem to find any kanthal or nichrome locally :/...

 

[merddyn2002]

Thanks for the advice, I will try taking some wraps off. I also would like to build my own but I can't seem to find any kanthal or nichrome locally :/...

Amazon.com: Kanthal 28 AWG Gauge A1 Wire 100' Roll .32mm , 5.27 Ohms/ft Resistance: Everything Else

 

[dice57]

Products - Lightning Vapes

 

[vapeasy]

Products - Lightning Vapes

The only question is.... What gauge? But that's something I can find in another thread.

 

[edyle]

resistance = resistivity x length / crossectionalarea = k1 x l / r^2

surface area of hot wire = length x circumference = k2 x l x r

length; r = radius

R = k1 x l/r^2 so l = R x r^2 / k1
A = k2 x l/r so l = A x r /k2

therefore: R x r^2 / k1 = A x r/k2

A = kRr

For the same resistance, the bigger the radius, the higher the surface area;

to get more surface area, you want a thicker wire, but then you will need more length to end up with the same resistance

 

[vapeasy]

Well I did some calculations and found this (these calculations may be a little rough but found what I was looking for.):

The goonk wire is 32GA.
32GA = 0.042979 ohms/mm

I took the wire out that was supposedly running 2.0 ohms.
It measured out to be 46 mm which equates to (46)(0.042979) = 1.977034 ohms
(Not bad, goonk)

So now my goal was to reach around 1.5 - 1.8 ohm by taking off a wrap. I tested my ohms by taking the diameter of the silica wick (2 mm) and finding the circumference which should be roughly around the length of 1 wrap.
I took that length and subtracted it from the 46mm coil I previously had on my nova to find the ohms I'm running now.

(2 mm)(π)= 6.283 mm

46 mm - 6.3 mm = 39.7 mm

(39.7 mm)(0.042979 ohm/mm) = 1.7063 ohms

New coil = 1.7063 ohms

I might even take another wrap off next time and see how that vapes.

One problem that I'm encountering is a burnt taste, I thought it was the rubber grommet, and for the most part it was, so I replaced it, but I'm still getting a little bit of gross burnt flavor and I'm also getting very low e-juice flavor. Any suggestions?

Could it be the extra piece of 2mm silica I put on the top of the coil to keep the vape from getting into the tank? Should I try cotton wick? What's going on?

 

[mackman]

Sounds like you put a lot of brain power into how to correct a junk coil built with cheap unknown wire and questionable silica. As suggested get some Temco kanthal A1 wire and build a coil to your specs.

 

[vapeasy]

Sounds like you put a lot of brain power into how to correct a junk coil built with cheap unknown wire and questionable silica. As suggested get some Temco kanthal A1 wire and build a coil to your specs.

Yeah and an ohm Meter while I'm at it so I don't have to do this math again lol. Maybe a helio or kayfun also...

 

[vapeasy]

One problem that I'm encountering is a burnt taste, I thought it was the rubber grommet, and for the most part it was, so I replaced it, but I'm still getting a little bit of gross burnt flavor and I'm also getting very low e-juice flavor. Any suggestions?

Could it be the extra piece of 2mm silica I put on the top of the coil to keep the vape from getting into the tank? Should I try cotton wick? What's going on?

Anyone have an answer?

 

[Aal_]

it might be the silica or the wire itself. you should try cotton to rule the silica out. but also it's been a long time since I vaped on vivnova, I am not sure if there is any other silicon/rubber thing in the mix.

 

[williebb123]

make sure your coil is not too tight and choking your wick , also check the rubber cap just incase i wouldnt think so most of the time its either the gommet or the wick

 

[xyanide]

Wrap a micro coil with 30 gauge, this will cover more of your wick than 32 gauge because you'll need to wrap more coils and produce that warm vape you're chasing. A multimeter from the DIY shop will help you out. I always wrap mine around a precision screwdriver and once you've done it a few times it'll be easier to work with than regular coils.
In my experience using cotton for a wick doesn't retain old flavors as much as silica does, especially when you dry-burnt silica.
Vivi novas are known to be fiddly devices and I only owned a mini in the past. The burnt flavor could be coming from improper wicking.

 

[edyle]

Anyone have an answer?

I don't think you mentioned what tank you are using?


-edit-
oh, sounds like vivinova.

You're running higher power now, so not surprising is you get burnt something; try twirling the tank to wet the coil area first; maybe at higher power the eliq just cannot wick upward fast enough.

 

[vapeasy]

I don't think you mentioned what tank you are using?


-edit-
oh, sounds like vivinova.

You're running higher power now, so not surprising is you get burnt something; try twirling the tank to wet the coil area first; maybe at higher power the eliq just cannot wick upward fast enough.

Yeah I've been doing that like mad. And I don't think I could get a burnt taste at 1.7 ohm 3.7 v.... It sounds like I could have the coil to tight or something of that nature preventing proper wicking....

 

[edyle]

Yeah I've been doing that like mad. And I don't think I could get a burnt taste at 1.7 ohm 3.7 v.... It sounds like I could have the coil to tight or something of that nature preventing proper wicking....

You changed the coil since last burnt taste? Once theres some gunk that has gotten burnt on the coil, the burnt taste might stay for a while.


3.7 / 1.7 = 2.2 AMPS of current..... yeah, I kinda think that 2 amps sounds like enough to BURN stuff.