question about ohms

Discussion in 'New Builders Corner' started by Fern2987, Dec 24, 2015.

  1. Fern2987

    Fern2987 Member For 1 Year

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    I have a sigelei 150 with mutation x v3.
    Did my first build but im kind of nervous about it being safe.
    Its reading at 0.5 ohms 5.2volts. 50 watts
    I used 24 gauge kanthal
    Wrapped it on a 1/8 drill bit 12 wraps.
    Can anyone help
     
  2. DED420

    DED420 Silver Contributor

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    As a new builder, read up about "ohm's law", and http://www.steam-engine.org/ should become your new best friend. Your 0.5ohm is a pretty standard sub-ohm build, and the Sigelei 150W (Series box mod) is capable of builds as low as 0.1ohm. Just make sure you have 2 married batteries (SonyVTC4-5/Samsung25r/LG-HG2 recommended) that are alternated every charge, make sure to check your build for hot-spots (Dry-Fire/Pulse your coils and check to make sure they are glowing from the center outwards and there's no shorts), then you should be good to go. Wick it up, Juice it up, Vape it up, Enjoy Life! :D

    Side Note: Start at lower wattages (20W or so) and slowly bump it up until you find your sweet spot, sub-ohm builds can get pretty rowdy sometimes.
     
  3. Fern2987

    Fern2987 Member For 1 Year

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    I did plenty of research before posting this question. Honestly i dont understand the charts. But everything seemed just the way tou described so i guess im good to go. Thanks
     
  4. WraZa21

    WraZa21 New Member

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    If your at .5 ohms thats very high resistance also the Sigelei is a regulated mod so it should shut down before any problems. Make sure your using good batteries as well keep them married (discharging and charging together) but for a .5 it just going to take longer to heat up and produce vapor. When you get to the Sub-ohms is when it gets to the point of double checking and testing and making sure everything is safe as possible

    Sub ohm .1 and under. Even though I checked everything and had the proper batteries I was nervous when I made a .08 build.
    Make sure you understand Ohms law, grab an ohm calculator, and Research your batteries as well.
    (Batteries are key to safe building as well)

    ohms law calculator

    Ohms Law
    Builder Info
     
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  5. f1r3b1rd

    f1r3b1rd Phantom Pilot Staff Member Senior Moderator VU Donator Diamond Contributor Member For 2 Years

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    Woh dude, do you have your decimal in the right place? What are you firing a 0.08ohm build on? and what kind of wire? I ask about your decimal because sub ohm is used to describe build below 1 ohm not 0.1.





    To the OP, that build should be safe, but please research ohms law, and battery safety and when yo get advice double check.
     
    Last edited: Dec 25, 2015
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  6. OBDave

    OBDave VU Donator Gold Contributor Member For 3 Years

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    I personally see little need to go below 0.2 on a regulated mod - even that 0.5 should work great with enough power applied to it.

    fat fingered flubs courtesy dumb mobile phone
     
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  7. CgS_Drone

    CgS_Drone Silver Contributor Member For 2 Years

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    Your off on your decimal WraZa21. Sub ohm is anything below 1.0 ohms.
     
  8. zaroba

    zaroba Gold Contributor Member For 3 Years

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    isn't below 0.1 ohms considered super sub ohm?
     
  9. JERUS

    JERUS Gold Contributor Member For 1 Year

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    Yeah I've seen below .1Ω referred to as super-sub-ohm, which seems fitting and that's when you should be getting nervous. With your Sig150 OP you'll be perfectly fine at .5Ω.

    All the advice you need has already been said but a few good links to favorite:

    http://www.steam-engine.org/

    That's your ohms law calculator, and coil wrapping guideline, just kind of all the little things that will help.

    http://liionwholesale.com/

    Trusted battery supplier, popular one on these forums, there are a lot of rewrapped batteries advertising false specs. The ones DED420 listed are the ones you'll want, need higher Amps and VTC4 are recommended, if not the Samsung 25r/LG-HG2 are about as good as it gets with the higher mAH (last longer).

    Like OBDave said stick above .2Ω and you'll be fine on that rig if you have good batteries (again this is important, Samsung, Sony, LG, it's these big companies that make the batteries, companies like Efest and many others simply rewrap them and package/market them, often with misleading specs). Also note though that the Sig150's built in Ohmmeter only goes one decimal place and it rounds. So if it's reading 5.2v on your mod according to ohm's law you're actually at a .54Ω resistance. Likewise you may have a .16Ω reading .2Ω and that makes a difference as your required amps changes and could cross a safety threshold. So a stand alone Ohmmeter is not a bad idea.

    Anyways, like has been said nothing to worry about. You're at 10amps with that setup, any decent battery can produce much more than that.
     
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  10. martinelias

    martinelias Silver Contributor Silver Contributor

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    .5 is fine. All of my builds always end up at .08-.16 and they do just fine. I usually vape at 110w-120w. I like a warm to hot vape though.

    Sent from my SM-N920T using Tapatalk
     
  11. WraZa21

    WraZa21 New Member

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  12. WraZa21

    WraZa21 New Member

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    my bad I placed decimal wrong and your correct
     
  13. WraZa21

    WraZa21 New Member

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    yeah I hit .08 its firing safely but batteries drain quick and I only firing once every few minutes but only last like 6 hits changed it to be at .1 today and its a whole lot better in my option and as a new builder I would just stay in the .2 area
     
  14. f1r3b1rd

    f1r3b1rd Phantom Pilot Staff Member Senior Moderator VU Donator Diamond Contributor Member For 2 Years

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    What mod? On a single battery mechanical you're looking at drawing 52.5A on a full charge, with that 0.08ohm build. That is not safe, imho.
    I definitely agree though, I would never tell a new builder to go below a 0.2. Being the old fogey that I am I try to tell them to stay between 0.4-0.5 until they get a little experience.
     
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  15. WraZa21

    WraZa21 New Member

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    I am using a duel hive Clapton build on a mutation x4 and a dark knight mech using Sony vtc4. Im actually drawing 46.25amps but the fast drain on the batteries keeps it cool. I have been using this set up for 2 weeks now. I also started using a 2.6 ohm on a hellboy as my first rig so that was my starting point but I had researched and my friends help me in that process.
     
  16. BigNasty

    BigNasty Diamond Contributor Member For 3 Years ECF Refugee

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    Still in the land of tard ohm.
    you are pushing that battery well past the safe amp limit, the pulse is mythical like rocking horse turds and frog fur.
     
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  17. JERUS

    JERUS Gold Contributor Member For 1 Year

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    Not saying it's a good idea, but isn't a fully charged battery still hitting more like 3.8v rather than 4.2v? Battery sag and power loss creating that gap. So with a Parallel mod with VTC4's you'd be close to safe but still not completely. (about 47 amps from a 3.8v on a .08Ω, but only about 45 amps from a parallel setup of 30amp cells). Just want to check that my understanding is correct, I'm not looking to push anything really, quite happy where I'm at within the safety protocols.
     
  18. f1r3b1rd

    f1r3b1rd Phantom Pilot Staff Member Senior Moderator VU Donator Diamond Contributor Member For 2 Years

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    Yeah, I did the math with 4.2 because MOST people do. He used 3.7v, i guess he figures correcting me for whatever reason would pull me into a debate and change the subject-
    That wasn't the point I was making though. Im old and have this crazy idea that numbers matter and giving + or - percentage tolerance that any company gives a product, its still unsafe in my opinion.
    There's no such thing as a 'good' battery failure.

    From battery tests run by @Mooch
    Bottom Line
    This is a good 20A cell.
    While the VTC4 runs cooler than other cells above 20A, like other cells it is still running way too hot. This is a 20A cell that can be forced to run at up to 30A if you're willing to accept a shorter cycle life and reduced margin for safety in case your mod autofires or your mech's button is accidentally pressed in your pocket.
     
    Last edited: Dec 27, 2015
  19. JERUS

    JERUS Gold Contributor Member For 1 Year

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    And that's why the only mech I have is a pipe mod that I toss a battery in once in a while when I feel like it but only at home, then take the battery out when I'm done.

    I usually keep my setup in my cupholder in my car, yesterday my brother sits down and pinches it with his thigh causing it to fire, didn't notice till I smelled some burning, luckily it had a 10s cutoff. Told him that's why I don't mess with Mechs ;)

    Anyways thanks for the heads up. I do have one setup on a single battery mod where I'm pushing up to 22amps at 4.2v (0.19Ω, haven't been able to get a 0.2Ω build, it's either that 0.19Ω or ~0.25Ω and I notice the difference in performance), thought I was good with a VTC4 but interesting info. I've seen a test also done showing relative safety in pulse firing the 20amp samsung 25rs but got the VTC4s thinking I'd be safer, still constantly think about heat of the battery though, and haven't noticed any temperature changes on them over the last few weeks using this setup.
     
  20. robot zombie

    robot zombie Silver Contributor Member For 2 Years

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    You don't have to worry about resistance on a mod like the Sig 150. That's for mech-users to worry about. Dual 18650, 100w+ regulated boxes follow different rules. They usually run the batteries in series and use a buck converter to trade voltage for the amount of current that ohm's law dictates is needed to power a coil with 'x' resistance at 'y' wattage.

    Assuming a given wattage setting, this means that whether you run a .1 or a 1.0, the current draw on the batteries will be the same - in spite of the fact that the current going to the coils is vastly different. It doesn't care about the resistance of the coil. It will pull however much current it needs from the batteries to generate that wattage. It's sort of a two-part circuit. In the first part, you only have your batteries and a buck converter. This part of the circuit operates independently of the coils. There's no resistor in the circuit, so ohm's law does not apply. It's only after the power passes through the buck converter that the resistance of your coil becomes a factor. Once the power passes through the converter, your batteries are no longer directly involved in how much voltage and current is being sustained. Current-wise, the buck converter serves as a buffer between your batteries and the atty, which in turn ensures a safe vape on even a .1 ohm coil.

    You have input current and output current. The input current is what's taken from the batteries. The output current is what hits the atty. Your output current can surpass the amp limit on your batteries so long as the input current doesn't.

    Lets say you drop a .1 on the Sigelei 150w. To hit 150w on fresh batteries (8.4v,) it will need to pull 20A. However, what actually hits the atty is 38A @ 3.9v. That's a safe 38A going to your atty. 20A @ 8.4v yields a little more than 150w. That's what your batteries give. 38A @ 3.87v yields exactly 150w. That's what the converter feeds to your atty.

    Another thing worth noting is that as your battery voltage drops, the amount of current that the mod will take from them increases. Let's assume the "low battery" cutoff is 6v. At that point, you will be pulling almost 28A to get 150w, so you will need 30A batteries. The highest you could run 20A batteries all the way down to the cutoff and without surpassing the limit would be 110w.

    Essentially, what this all means is that if your resistance is within the range that the mod will fire, then it is safe to use. You should worry more about your wattage setting, though even that isn't as important. You can run most 20A batteries (VTC4's, 25r's, HE4's, and so on) all the way up to 150w and it will only be towards the end of the discharge cycle that your batteries will be significantly taxed. It will hurt your battery lifespan and runtime, but most likely not your face or your hand.


    And on tard-ohming... ...I've never understood why people would want to super-sub-ohm with a single 18650. It's not the heat that I worry about, nor would I fear an internal short in the battery, as the internal resistance on the batteries we use is on the order of milliohms. Its just that the sag on a .08 draw has to be insane. It's probably kicking out far less than 3.7 volts under load. I can't help but think that the performance can't actually be better than something more within the limits of what the battery can handle.

    Super-subbing on a tube mod just seems risky, impractical, and ineffectual. The power boost can't be very high compared to the strain placed on the battery. There has to be a point of diminishing returns with regards to current draw. Past a certain point, the increase in current will stop making up for the drop in voltage, which would mean that not only would wattage no longer increase, but actually decrease as the resistance gets lower and lower. I'm not sure how low you would have to build before this would happen, but I suspect that a .2 with 9A of headroom would probably outperform a .0x that even a true 30A battery would be struggling to power.
     
    Last edited: Dec 31, 2015
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