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Build recommendation

Discussion in 'Cloud Chasers' started by Cacique, Jul 11, 2015.

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  1. Cacique

    Cacique Super Member ECF Veteran

    May 4, 2014
    Orlando, FL
    I'm looking for some build recommendation to get the most, cloud wise obviously, out of my Sigelei 150 and Mutation Xv4, I also have an Airek. My current build is .56 ohms, 24g 12 wraps around 3.5mm at 150w. I've used different ohms and was at around .3 before. I've tried .2 dual parallels too.

    This was my parallel build, but I usually build them so they look like this.

    On the MXv4 I place the coils over the bottom air flow and put them low and close to them. On the Airek I have the coils pretty much level with the top air holes.
  2. State O' Flux

    State O' Flux Vaping Master Verified Member ECF Veteran

    Jul 17, 2013
    With 0.56Ω net resistance (I get closer to 0.60Ω at 12 wraps)... you have:

    250.44 mm² per coil of functional surface area. Quite good.
    At 150 watts, you have a heat flux of 296 mW/mm². Warm, but certainly not overly so.
    Heat capacity (each coil) 105.74 mJ/K. A bit on the slow side, but common for the build.

    SE build reference

    There is nothing wrong with the above numbers for surface area and coil radiant heat... in fact, it's a good compromise of resistance, components and available power.
    Your heat capacity (time to temperature - smaller number = faster ramp-up time) is on the slightly slow side, but... chances are, you're used to that and find it acceptable.
    Obtaining high surface area, with an acceptable heat capacity, at a useable heat flux... is a balancing act. All functional values are interdependent - changing one changes several.

    The trick is to find what works for your personal habits, components and juice blend/flavor.

    A few options, with your practical 150 watt limit, are:

    • Using your 24 gauge wire, at the slightly higher net resistance of 0.70Ω. Suggested, as an experiment.
    Surface area 313.85 mm². Noticeably greater.
    Heat flux 237 mW/mm². Noticeably Cooler.
    Heat capacity (each coil) 132.17 mJ/K (Perhaps) noticeably slower than your build.
    (A slight adjustment to 0.65Ω would decrease surface area, increase heat flux and reduce heat capacity)
    SE build reference

    • Use 23 gauge wire at 0.40Ω. Not recommended, other than as an experiment.
    Surface area 252.94 mm². So close as to be a wash with your build.
    Heat flux 292 mW/mm². Slightly cooler.
    Heat capacity (each coil) 120.09 mJ/K Slightly slower than your build.
    SE build reference

    • Use 22 gauge wire at 0.30Ω. Not recommended, other than as an experiment.
    Surface area 268.4 mm². Slight functional improvement.
    Heat flux 275 mW/mm². Slightly cooler, but not enough to matter.
    Heat capacity (each coil) 143.22 mJ/K. Even slower.
    SE build reference

    We can go on and on like this... but producing a build that is substantively better than what you already have is not an easy task.
    The only way to increase surface area substantially, while maintaining a warm HF and semi-reasonable HC is to increase wattage. As you move closer to absolute zero resistance (dead short), it becomes increasingly more difficult to avoid an increase in heat capacity, while maintaining a high value surface area.

    • Example at 0.2Ω with 20 gauge wire at 200 watts:
    Surface area 359.08 mm².Substantial increase.
    Heat flux - 275 mW/mm². Similar to original.
    Heat capacity (each coil) 241.4 mJ K-1. Substantial increase in time lag to temp.
    SE build reference

    If you are willing to accept a lower heat flux ( 206 mW/mm²) and slow heat capacity , you can obtain the terrific surface area of the last example, with your existing 150 watts.

    SE build reference.

    In closing, I suggest you click the sigline hyperlink below and learn how to use the SE coil modeling program. With it, you will be able to optimize builds, within the limitations of equipment and components.
    • Like Like x 4
  3. Cacique

    Cacique Super Member ECF Veteran

    May 4, 2014
    Orlando, FL
    Thanks for the reply, it really helps. I need to pick up some wire soon, so I'll figure out a couple more other than my usual 24g. Does heat flux affect cloud production greatly? With my long, and I think somewhat quicker draws on the Mutation Xv4 and the Airek it feels quite cool, much cooler than my Cthulhu RTA, 24g .3ohms at 70w. But, obviously, the RTA doesn't have nearly as much airflow as the MXv4 or the Airek.
    • Like Like x 1
  4. State O' Flux

    State O' Flux Vaping Master Verified Member ECF Veteran

    Jul 17, 2013
    Coil surface area is the functional surface that you can expose a wick to... and all you really need is an adequate heat, in a reasonable amount of time.
    Theoretically, you can never have enough surface area... but then again, if that surface area is at the expense of other important factors, then maybe backing down on surface area to obtain a preferred heat flux, or get heat capacity down to a lower (faster) value... is a good idea.

    Heat flux is the coil(s) radiant heat, expressed in milliwatts per millimeter of coil surface area... squared. For our purposes... it's simply how warm you perceive your vape to be. There are no hard fast rules to it, as some like mid 150 mW/mm²... while others shoot for well into the 300s and beyond.

    I look at surface area first, then heat flux. I have a sort of personal, semi-floating min/max for various RDAs/RTAs... but if you were to average, it'd be around 265 mW/mm² +/- 50. I try to stay above 200 and generally, unless the atty has some serious air flow, not much more than about 320.
    A slow heat capacity, with short draws can give the impression of a cool vape, even if the peak temperature is warm.
    I use nothing but mech mods at Ohm's law parity values, so my builds have to be optimized for the available wattage at a given resistance... my draws can be close to 10 seconds from an RDA.

    Where was I going with the above? Oh yeah. o_O You might, depending on wicking performance, try firing the atty for a few seconds prior to a draw - then take your draw - perhaps a bit longer that what you consider normal... just to gauge the temp and time to temp a bit better.

    So many things to play with... so little time. :rolleyes:
    • Like Like x 2
  5. State O' Flux

    State O' Flux Vaping Master Verified Member ECF Veteran

    Jul 17, 2013
    Ya' know... I'm going to refine what I said above... a bit.

    I use nothing but mechs, so I look at the wattage available for a given resistance, at 4.2 (or less) volts. From that, I have to come up with a build that gives me the most surface area... while staying within my heat flux range. I may have to adjust surface area, wire gauge and number of coils in parallel... if the HF is too hot or cold, or if the HC is too slow.

    You on the other hand, can be less concerned about what I must do... matching gauge and coil count in parallel to Ohm's law resistance/wattage parity.
    Within your 150 watt limit, you can build to a broader range of variables. If it's too cold, you can "force" wattage to increase temperature... so at the very least, heat flux can be an independently tuneable element.

    This is why when people ask me what VW APV to get... I tell them to get the most wattage they can afford. You can always turn it down, but you can't turn it up past your limits. 200, 300 watts means almost no limits. One of these days, when they make a completely reliable 400 watt VW APV... I might have to retire my mechs. (but I doubt it)

    Believe it or not, there's a - not completely insane or even unreasonable - case to be made for 500 or more watts. :confused:
    • Like Like x 1
  6. Cacique

    Cacique Super Member ECF Veteran

    May 4, 2014
    Orlando, FL
    Thanks for your posts, I really appreciate them. When I got my Sigelei 150 a few months ago I was using a SMPL mech, wanting more. I automatically started building my coils, using Steam Engine, for what I thought was a good build to use at 150 watts, then eased my way there from 100w. Now it's all I use with my RDAs, using my RTA at 70w but trying to figure out how to push it higher lol. I feel like I'm starting to out grow it already, which really surprised me, so a higher wattage device sounds really good to me too.

    Do you see much difference between dual parallel coils and dual coils wrapped to the equivalent in wraps to the parallels? I tried to test that out myself and I'm not sure I could find a difference, but it was a while back. I want to start playing with this, but I don't have the time to get absorbed into trying a coil build while having a good one since I got a long day tomorrow. Thanks for all the info and ideas.
    • Like Like x 1
  7. State O' Flux

    State O' Flux Vaping Master Verified Member ECF Veteran

    Jul 17, 2013
    I've tried lots of complicated coil "styles", and some "stupid low" net resistances... but I keep going back to basic dual parallels from 0.2Ω ~ 0.45Ω at 40 ~ 90 watts. Quick - easy - works.

    Side by side dual parallels (two wires per post pair X two sets) is a quick and easy way to get, what amounts to quad parallels... if your post holes are large enough, but unless you're running thin wire, and/or low resistance, the HF can be pretty cool when working with Ohm's law wattage/resistance parity.

    You can, up to your current 150 watt limit, bypass those concerns with forced wattage.
    • Like Like x 1
  8. RustyStar

    RustyStar Full Member

    Jul 2, 2015
    Running twisted, dual 28 gauge kanthal coils on parallel from 0.2 ohms, 18-30 watts.

    I am using a Dark Horse RDA with 15mm diam. monster tip which gives high airflow. The intake ports are directly facing the coils.

    Higher VG juice to PG mix will give thicker plumes.

    Last but not least, high capacity lungs to take a hit between 6-7 seconds.

    Sent from my Z3
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