Regulated : parallel vs more wraps

[Kazuko]

Hi,

I'm mostly using a mech mod these days, so I've come to learn the build that works fine for the wire I like the most. I'm kinda replicating it on my regulated mod as well, but as I've read most people don't care about it and make cloudy builds at more than 1ohm, I figured I'd dig deeper on that topic!

So, for this example, I'll just use my preferences as reference. With 26AWG KA1, 3mm ID builds, the wrap count that works fine for me is 5 half wraps. Let it be a simple single coil, a 2 strands parallel coil, or simple dual coils (two parallel dual coils is too low a resistance for my battery's CDR). Anyway.

The "weak" simple build with a single strand would be .66ohm, the heat flux I like (around 280mW/mm2) would be provided by 21W.
Now, if I want twice the surface area, because I like clouds, but it's a single coil rda, I can basically :
- use 2 strands to make a parallel coil
- double the wraps count (being half wraps it won't be exact, but bear with me)

Both would get the wanted heat flux at the same wattage, which is twice the previous one, so 42W. The thing is :
- the parallel coil would be .33ohm
- the wraps-bro-wraps coil would be 1.32ohm (not really, that's naive maths, counting 9 full wraps with legs twice the length, but actually keeping 5mm lengths with 10 half wraps gives around 1.34ohm, so really close !)

So. Both builds have roughly the same surface area. Both have the same heat flux per watt. But one is the quarter of the other's resistance.
Which one would actually work better? That'd be accounting for ramp up (and cool down), wire heat (I guess it should be the same as the heat flux is the same, but I'm not sure), and all the other factors I can't think of, 'cause it's getting late in France and I'm tired as f* atm.

 

[mimöschen]

It depends on the voltage your mod can provide. To provide 42W on a 1.32ohm coil, the mod has to put out about 7.5V.
So if it has a boost circuit, that shouldn't be a problem, most dual/triple battery mods don't have one though, so performance will decrease when the batteries get drained.

When your mod can't provide the necessary voltage, you're better off with a parallel build.

 

[Kazuko]

It depends on the voltage your mod can provide. To provide 42W on a 1.32ohm coil, the mod has to put out about 7.5V.
So if it has a boost circuit, that shouldn't be a problem, most dual/triple battery mods don't have one though, so performance will decrease when the batteries get drained.

On a regulated mod it's just going to draw the current for 42W, whatever the resistance is, so the battery drain should be exactly the same, right ?

 

[NickBurkhardt]

Don't be so picky about watts and heatflux, you're going to pull your hairs out on that issue .
Just relax, make some test builds and try them out. I recommend to buy a battery with a decent cdr, sony vtc5a. Ever thought about switching to stainless steel ss316L or nicr80 wire ? I've heard a bird whistle that mech users swear on those wires ...

 

[bwh79]

On a regulated mod it's just going to draw the current for 42W, whatever the resistance is, so the battery drain should be exactly the same, right ?

If the mod can output the requested voltage, it's the same drain on the batteries, yes. But, some mods can't output more than the battery's native voltage (charge state). If you've got 2 cells at 3.5v each, that's 7v in series. At that charge level, the mod can't output more than 7 volts, regardless of how many watts that makes. 7 volts on a super-sub-ohm coil is lots of watts, but 7 volts on a 1.5 ohm ain't all that much (about 32 watts). Now, when the batteries are more fully charged you'll get up to 8-8.4 volts at the start and so the mod can provide that much more wattage, on either coil, but as the batteries wear down the max watts will decrease either way, it's just a lot more noticeable, and a lot sooner, on the high-ohm-high-wattage builds.

 

[NickBurkhardt]

@bwh79 Exactly, I couldn't put it together well enough with my limited english (to my apology, it's late and I'm too tired).
Good night everybody !!!

 

[bombastinator]

My method for this kind of situation is to do a twist coil. You get the surface area of clapton with all heating wire. Not too fond of parallel coils myself.

 

[Zakillah]

The main reasons for using parallel builds in regulated devices are:

Getting in a resistance region that'll work for the intended Watts. If you use thinner wire and want to build bigger coils you'll end up with very high resistance. Say you shoot for coils that'll work at 60W; a 2 Ohm build wont do because of Voltage limitation. Wrap it parallel and the same build goes down to a workable 0,5.

Easier to build and more stable coils. Fiddling with a single piece of very long wire is annoying. Wraping it 20 times over is tedious. Its much easier to just fold it in half and do a 10 wrap parallel.
The finished coil will also be alot more stable making it easier to install and wick.


Thats one of my usual builds, just as an example:





Other then that there is no real reason for doing parallel coils. A 5 wrap parallel will behave exactly the same as a 10 wrap with the same wire.

 

[Kazuko]

Thanks for your detailed answers!
I think my regulated mod can go up to 9V so I actually forgot there was this kind of limitation.
I'll stick with my parallel builds then!

 

[Kazuko]

Ever thought about switching to stainless steel ss316L or nicr80 wire ? I've heard a bird whistle that mech users swear on those wires ...

I tried using SS304L, but the resistance increase from the heat makes it even harder to design a good build for a mech mod, and as it was an expensive wire, I don't want to waste it on failed builds. I will give it some more tries on a regulated, so if it's sucks in bypass mode I can still TC or VW !
Ni80 however has picked my interest. I'm waiting for payday to order some flat wire and try this one

 

[NickBurkhardt]

@Kazuko Payday is the keyword
I need new swivels, a coil jig tool & better alien makers
I have enough wire here, but I need better tools to build

 

[Kazuko]

@Kazuko Payday is the keyword
I need new swivels, a coil jig tool & better alien makers
I have enough wire here, but I need better tools to build

Truth is I changed my mind and bought a clapton wire today

 

[NickBurkhardt]

Hehe, a good choice

 

[Don29palms]

The main reasons for using parallel builds in regulated devices are:

Getting in a resistance region that'll work for the intended Watts. If you use thinner wire and want to build bigger coils you'll end up with very high resistance. Say you shoot for coils that'll work at 60W; a 2 Ohm build wont do because of Voltage limitation. Wrap it parallel and the same build goes down to a workable 0,5.

Easier to build and more stable coils. Fiddling with a single piece of very long wire is annoying. Wraping it 20 times over is tedious. Its much easier to just fold it in half and do a 10 wrap parallel.
The finished coil will also be alot more stable making it easier to install and wick.


Thats one of my usual builds, just as an example:

View attachment 750283



Other then that there is no real reason for doing parallel coils. A 5 wrap parallel will behave exactly the same as a 10 wrap with the same wire.

A 5 wrap paralell will not behave like a 10 wrap with the same wire.

 

[Zakillah]

A 5 wrap paralell will not behave like a 10 wrap with the same wire.

On a regulated? Why not? Care to explain?

Same, well, everything that matters. Mass, surface area, coil size and therefore heat flux.
Only difference is resistance, which doesnt matter. I dont see what makes you say that.

 

[Don29palms]

On a regulated? Why not? Care to explain?

Same, well, everything that matters. Mass, surface area, coil size and therefore heat flux.
Only difference is resistance, which doesnt matter. I dont see what makes you say that.

Resistance plays a role even on a regulated mod. A 10wrap single wire coil will not perform the same as a 5 wrap parallel coil. Try building it and you'll see the difference.

 

[Zakillah]

No it doesnt.
40 Watts are 40 Watts. It doesnt matter whether its 0,5 Ohm, 4,x Volts or 2 Ohm, 9 Volts.

 

[Don29palms]

No it doesnt.
40 Watts are 40 Watts. It doesnt matter whether its 0,5 Ohm, 4,x Volts or 2 Ohm, 9 Volts.

You're full of crap but whatever. If people listen to your garbage then it's their own waste of time and money.

 

[Zakillah]

What exactly are you doing here?
You say there is a difference, but dont explain what it even is and why.