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Variable wattage mods -- does coil resistance effect anything besides battery life?

Discussion in 'New Members Forum' started by mobocracy, Nov 1, 2013.

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  1. mobocracy

    mobocracy Senior Member ECF Veteran

    Oct 21, 2013
    [Posting here because I'm too new to have enough posts to post in the VV/VW forum]

    I'm still pretty new but getting a fascination with VV/VW mods, like maybe a Innokin SVD from Fasttech.

    When using a VW mod, what does coil resistance effect besides battery life? From what I've read, part of the idea behind a VW mod is to be able to use a fixed amount of power via the mod detecting coil resistance and adjusting voltage output to produce the desired wattage.

    Presumably this means that for a given wattage the coil resistance wouldn't matter to anything except battery life, with a lower resistance coil causing lower battery drain. But something else tells me it's not that simple and that there may be other differences. I'm just speculating but maybe coil life might be better with lower or higher (my guess would be higher) resistance or some other factors.

    Can anyone enlighten me further on coil resistance selection when using a fixed-power (variable wattage) mod?
  2. Donnie Narco

    Donnie Narco Full Member Verified Member

    Oct 27, 2013
    San Diego, CA
    I am pretty new myself and would love to learn more about this. I have an iTaste SVD and love it, but I don't understand much about the VV/VW world. I know that when I started, I was vaping at a very low (underpowered) setting, so I was leaking everywhere. I am getting better now, but still I have so many questions.
  3. mobocracy

    mobocracy Senior Member ECF Veteran

    Oct 21, 2013
    I've seen the voltage vs. resistance charts with the ideal power envleopes and I understand the basic electrical properties (ie, Ohm's law) but why you'd pick a coil of 1.8 vs. 2.5 when using a fixed-wattage mod is kind of mystery.

    I get why you'd choose a specific resistance when using a fixed-power battery, since the coil resistance is the only way you'd adjust power output. A variable voltage (but not wattage) "spinner" battery would seem to make less of a difference, provided you "did the math" and made the appropriate voltage adjustment relative to the coil resistance to get the desired wattage.

    The ideal power envelopes seem slightly larger on higher resistance coils, presumably allowing for a finer-grained "sweet spot" and maybe that's what it's about.
  4. wv2win

    wv2win ECF Guru ECF Veteran

    Feb 10, 2009
    GA by way of WV
    Variable watt PV's are supposed to "automatically" adjust the power to a change in the resistance of the head you are using in order to maintain your original setting. And they are of course regulated. Different resistance heads will deplete a battery at different rates but the difference should not be too significant if you are using good batteries and a good charger.

    A good VW PV should be an advantage to a newer vaper, as they are closer to set and forget.
  5. KenD

    KenD Vaping Master ECF Veteran

    Aug 20, 2013
    Stockholm, Sweden
    A 1.5 ohm coil draws 2.6 amps at 10 watt whereas a 2.5 ohm coil draws 2 amps at the same wattage, according to ohm's law. In theory, then, a higher ohm coil should use less power and the battery should last longer. However, voltage conversion efficiency (or something of the sort) come into play and things aren't that simple in real life. Someone with more expertise should be able to answer why that is and how battery times are actually affected. I haven't noticed much difference with different coils.
  6. vicflo

    vicflo Super Member Verified Member ECF Veteran

    Dec 25, 2009
    how big of a difference does quality of batteries matter you may ask?

    standard vaping is ~2amps... ~1.2 being the low end and ~3amp being the higher end. If you look at some batteries there is very little difference and with others its night and day.

    depending on the atomizer, higher resistance coils CAN but not always have thicker gauge wire which can lead to a longer lifespan as a cooler vape. LR coils at the same wattage can get hotter quicker usually due to smaller gauge. both of which affect vapor production and flavor, which of course is also dependent on your specific type of atomizer.
  7. DKP#

    DKP# Super Member ECF Veteran

    Nov 27, 2012
    Missouri, USA
    I think that's the main reason, Well put.
    Too low of resistance and you won't have as much useable range. To high R and you won't be able to get it hot enough.

    Something I've thought about but don't know if is true is that higher resistance coils have longer wire so that the overall power (heat) is spread out over a larger area. This would give you a cooler vape at the same power or allow you to apply more power without burning.

    The reason I don't know if it's true, is because they might just use smaller wire to get the higher resistance so the overall length wouldn't be increased. Then wire surface area would actually decrease with higher R.
  8. Enoch777

    Enoch777 Super Member Verified Member ECF Veteran

    Sep 6, 2013
    Midwest, USA
    I'm just putting my experience out there. I use low resistance micro coils, preferably at 1.3Ω @8W on either Smoktech SID or Innokin MVP v2. Since switching to LR my batteries seem to last, well, around the same. Maybe a tiny bit longer, around 30minutes to 1 hour extra use. Hard to say without putting it all on paper.

    At any rate, my coils heat up pretty dang fast, produce loads of vapor, and I don't find myself hitting the cut off very often at all. This might be one reason my batteries "seem" to last longer. Must also consider that if you're trying to get the same hit off a standard resistance coil as you would on a low resistance, you will definitely need to take a much longer pull or kick the watts up even higher.

    All I can say for sure is, I use two APVs, and I MUCH PREFER low resistance coils. Why? I already said why! PREFERENCE! So the answer to your question is as simple as that, i.e. use whatever you prefer!

    Vape well, vape often! :vapor:
  9. Ryedan

    Ryedan ECF Guru Verified Member ECF Veteran

    Mar 31, 2012
    Ontario, Canada
    The issue of battery output vs device output in a regulated PV and if high voltage gives better battery life are great questions and they come up every once in a while here. Rader2146 has answered these much better than I ever could here.

    It looks complicated, but it's not too bad to follow though. In a nutshell, the battery in the PV always puts out the voltage it has because of it's state of charge (between 4.2 and about 3.3V), not the volts that you set the PV at, or the watts at if it's a VW device. What happens is the PV exchanges current (amps) for voltage to make the power you asked for. It's the watts the PV puts out that determines how long your battery will last.

    Read Rader's blog for all the details.

  10. mobocracy

    mobocracy Senior Member ECF Veteran

    Oct 21, 2013
    For a given fixed power, would the coil temperature be meaningfully different between different resistance coils? In theory, a lower resistance coil and a higher resistance coil operating at the same wattage should operate at the same temperature as they are both absorbing the same power, just at different voltages. There may be a time-to-heat difference, but only by milliseconds.

    I can see, though, where coil durability would matter if the higher resistance coils are more wire (thicker or longer) than lower resistance coils, but it's kind of not clear to me how (short of burning them up) coils wear out, either. Maybe they get buildup over time that causes them to need more power (longer draws) to reach vaping temperature.
  11. dice57

    dice57 Vaping Master Verified Member ECF Veteran

    Sep 1, 2013
    Mount Vernon, Wa
    a lot depends on where you vape at. I vape at max watt output that my devices are capable of. That is 15 watts. Some times more, if I take the kick out my mech mod to see if my current build is wicking well enough. Since the max on most devices is 15 watts, if you start out on say a 2.4 ohm coil, well the maximum I can vape is 6 volts on the Provari, giving me my desired 15 watts of output across the coil. Now with most coils, once it is used for a bit the ohms can drift up, and then I am vaping at on 12 or 13 watts. For that reason I like my builds to be .9 ohms to 1.4 ohms max. That way I can use them on my Provari or my kicked mech mod, with out a problem and be able to get some good life out of the build without losing my 15 watt threshold. Also if you are using a mech without a kick, or a non variable device, then you only have the voltage that is coming out of the battery producing the watts that the ohms of the coil puts out.

    I find that the more watts you use the faster I go through batteries. Once I started using build that could wick enough juice at 15 watts, I could burn through 4 18490's in a day. I can also vaporize 12 to 15 ml of juice in a day too, more on my days off.

    Like everything else in the world of vape, finding ones preferences, of ohms, watts, gauge of wire, nic level, VG/PT ratio, flavors, attys.... is a matter of trial and error, and always changing once you try different things and styles and builds and...

    In my different rba's I have 4 different style of builds, once I think that I've found the best answer, I'll try something else that pops into my head. hmm, what if I combine a micro style build with a genesis style build with cotton, what would I get. Apparently a pretty dang good vape. But so is my Vertical mounted dual serial coil build with an external wick.
  12. DKP#

    DKP# Super Member ECF Veteran

    Nov 27, 2012
    Missouri, USA
    If the different resistance is obtained by using different wire of the same length then the wire temp would be the same for a given power.

    If the different resistance is obtained by using the same wire but different length then the longer wire would dissipate less power per inch so would be cooler. My baseboard heater and stove burner may use the same power but the burner is smaller so the power is dissipated in a smaller area so it's hotter.

    In my limited experience, the wicks wear out, not the coils. Coils can be "dry burned" to get rid of the buildup.
  13. ZW99GT

    ZW99GT Senior Member Verified Member ECF Veteran

    Jul 31, 2012
    I wrote this and then stepped away from the computer for a bit. The last few posts were very informative.

    Using VW, in theory battery life should be the same no matter what resistance coil you use. Your battery is a fixed voltage, your resistance load is also fixed. The driver in the device manipulates the input voltage and current to produce the output ( output voltage and current) you calculate using ohm's law. Power is Power, there is nothing magical going on inside your APV. As your battery dies, the device attempts to regulate the same output voltage and current, which means the input voltage drops and the input current goes up every time you hit the fire button.

    15W input = 15W output

    For 1ohm
    4V X 3.75A (Battery side) = 3.87V X 3.87A (510 connection)

    For 3 ohm
    4V X 3.75A (Battery side) = 6.71V x 2.24A (510 connection)

    *** This is all assuming an arbitrary input voltage under load, no power loss from the circuitry, that the driver is similarly efficient over it's entire range, etc.... which is not meant to be exact or even correct.

    Real example, my vamo at 12W, half charged battery unknown voltage under load

    2.6ohm clearo at 12 W, my vamo pulled 4.2A from the battery
    1.25ohm DC carto at 12W, it showed 4.27A from the battery
  14. Elwing

    Elwing Full Member

    Feb 20, 2014
    Texas. USA
    A lot of great information you guys have given.. Thanks!!!!
  15. dykealiscious

    dykealiscious Ultra Member Verified Member ECF Veteran

    Apr 25, 2014
    I know this is an old post, but you have touched on something for me. I like to vape at the 1.5-1.8 range, which I'm willing to negotiate as I learn all this. I'm great at making coils now and am waiting for some 28g, previously using 30g. This will help some of my heat-up-faster issues. But I've got a kick coming in the mail, should be here today, and putting that in my mech I assume cranking it up will help heat my coils faster, yes? Not too worried about battery life. I've got good batteries, and multiple devices to swap out as I charge. Presently I'm running a single coil on a nimbus (also have an origin v2 on the way, it's a much better atty) because I prefer dual coils but then that takes even LONGER, or longer draws, to get the vapor I want so I've scaled down to one coil until the kick comes. Flavor is bomb, partly because I'm using micros, and so I'm just wondering if that added kick is going to help solve my heat up problem.
  16. deftonerdad

    deftonerdad Full Member

    Jun 14, 2014
    United States
    Been reading all day and can not find a answer to my question. I own a vamo v5 currently use a 1.2 coil with a 2000mah 10amp battery. My question is if buying a 30amp battery will create more/ hotter vapor? I've read the mah means it'll last longer but I can't find a definitive answer on amps. I currently vape at full power(15watts) on a kraken 1.2o triple twisted 32g kanthal coil and it just isn't giving me the burn I like or clouds. Just wondering how to get the most out of my vamo. Any advice is greaaaaatly appreciated guys and thank you in advance
  17. ElConquistador

    ElConquistador Ultra Member ECF Veteran

    Mar 24, 2013
    I don't think a higher amp rating battery will make any difference with a regulated mod. You're limited by the Vamo, not the battery.
  18. BladeZ

    BladeZ Senior Member ECF Veteran

    Jul 14, 2011
    Dortmund, Germany
    So is it actually okay to run 3ohms coil on 15w power..?
    It produces 6volts or it pump out 6volts from the battery to the coil..?

    Normal battery pump out 4.2v(at fully charged) without a kick, but if i use a VW kick set at 15W run on 3ohms coil, I can get 6v.. Is it save to use 6v from a single battery..? I feel like I'm pulling too much voltage from the battery..
  19. dykealiscious

    dykealiscious Ultra Member Verified Member ECF Veteran

    Apr 25, 2014
    I think as long as your imr battery can handle that, for example Sony high drains, depending on the version, cam handle 20-30watts. It is important to get the right battery.
  20. f1vefour

    f1vefour Vaping Master ECF Veteran

    Dec 3, 2013
    Stack two 18350's and switch the VAMO over to voltage, raise the voltage to 6v and enjoy your newfound power.

    1.2 ohm X 6v = 30 watts drawing the full 5 amps of the chip.
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