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How is sub-ohm vaping dangerous?

Discussion in 'Rebuildable Atomizer Systems' started by johnlikestovape, Aug 30, 2013.

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  1. johnlikestovape

    johnlikestovape Full Member

    Jul 21, 2013
    Los Angeles, CA
    I hear all these horror stories about how the battery can explode if you keep it firing for too long.

    I want to understand how subohming is dangerous. Not "because the battery can explode" or "the taste is terrible". Is it because the amps are too high, etc? Because the battery is using all of it's power? I guess I'm looking for a more technical explanation.

    I don't really go below .6-.7 ohms, but I think it would be good to know what could happen if I accidentally did (or even purposely).

  2. Peterdante

    Peterdante Full Member Verified Member

    Aug 28, 2013
    Los Angeles
    i do .2 all the time.
    and my buddy does .1's even.
    just make sure your using good batteries and dont run em to empty.

    as for the tech explanation i couldnt tell ya.

    just be cautious. (dont fire for overly extended durations) and your good.
  3. MarKa

    MarKa Senior Member ECF Veteran

    Aug 11, 2013
    Basically, the voltage of the battery matched with the resistance of the rebuildable generates way too many amps. Most batteries have an amp capacity of about 10-12amps. Doing the math, a 4.2v battery on a .3ohm rebuildable generates 14 amps. Most batteries arent intended for that many amps.

    Look up the amp capacity of your specific battery and the principles of Ohms Law to learn more for yourself :)
  4. Peterdante

    Peterdante Full Member Verified Member

    Aug 28, 2013
    Los Angeles
    Sony 30 amp batterys ...?:)
  5. WattWick

    WattWick Vaping Master ECF Veteran

    Feb 16, 2013
    Cold Norway
    ANY use of batteries can be dangerous if you use batteries that can explode when stressed beyond their capabilities or shorted.

    Don't use batteries that use potentially explosive chemistries. Don't use batteries that are not up to the current draws you plan to put on them and then some. Don't short your batteries.

    Pretty much the same as any kind of vaping. But, some people seem to think that using proper batteries only apply once you cross that magical 1 ohm border. Their loss (of fingers and/or face).
  6. Rule62

    Rule62 Vaping Master Verified Member ECF Veteran

    Oct 28, 2011
    Melbourne, Florida
    I don't ever build below about .8 ohms, but lots of folks do. From what I've seen, most battery failures are a result of rapid discharge, either by the fire button inadvertently being pushed for too long, or batteries being shorted from metal objects completing a circuit, like carrying a battery around in a pocket or purse, along with keys, change, etc.
    All of the batteries we use in mods have a maximum safe discharge rate, expressed in amps. If the maximum discharge rate is exceeded, the battery is in danger of failing. Batteries do different things when they do fail, depending on the type of battery. Some will explode or catch fire when they burst. Others, like "Safe Chemestry" batteries will burst, and discharge a pile of hot goo.
    IMO, before anyone delves into the world of rebuilding, a person should have a basic understanding of ohms law, and how it relates to the batteries and coils you are using. You don't need a degree in electrical engineering. Just a basic understanding.
    You also need to know what to do when something goes wrong, which likely will, at some point in your rebuilding career. Batteries don't usually fail without warning. The first sign is that either the battery or the mod you're using will begin to get very very warm. This means that something is wrong. At this point, stop using it immediately. If possible, remove the battery from the mod, get it out of your pants pocket, or purse, and put the battery someplace where it isn't likely to damage anything surrounding it. Because once a battery bursts, there's nothing you will be able to do to stop it. It's a runaway.
    I may get flamed for this; but I'll say it anyway. There are some B&M shops that are offering coil building as a service; either for a fee, or as a free service to customers. I recently read about one shop where a shop employee set up a new customer, who had never used an RBA before, with a .3 ohm coil. That's crazy! JMO, but I don't think shops should be offering this service. Because if the user doesn't at least have a basic understanding of RBAs, what's safe and what isn't, and what to do when something gore wrong, they shouldn't be using RBAs until they do.
  7. The Yeti

    The Yeti Ultra Member Verified Member ECF Veteran

    Oct 19, 2009
    Black Hills, SD
    To answer your original question, I present a perfect example here:

    It's people like these that will get into trouble....going under .5 ohms without any idea of why they shouldn't.
  8. Rule62

    Rule62 Vaping Master Verified Member ECF Veteran

    Oct 28, 2011
    Melbourne, Florida
    This is the type of advise that should never be given. If your buddy is building .1 ohm coils, he's an idiot. There's no other nice way to put it.
  9. John_

    John_ Ultra Member Verified Member ECF Veteran

    mA of DC current can kill you. I have no idea why running 10-30A through a device the size of your hand is dangerous.
  10. WattWick

    WattWick Vaping Master ECF Veteran

    Feb 16, 2013
    Cold Norway
    Pulling lots of current from a battery capable of delivering much less current can harm you pretty badly. It can damage the battery in a split second (i.e cause internal shorts) and set off a chain reaction known as thermal runaway. That is, heat trigger a chemical reaction that produce heat that trigger a chemical reaction that produce heat... and so on.

    Given the right (or more correctly, the wrong) chemical composition of a battery, this can result in hot gasses venting, a fire and/or an explosion.

    That's not a worst case scare scenario. It is what will happen if you mistreat an inadequate battery of the wrong chemistry for near-face operation.
  11. davewuvswaffles

    davewuvswaffles Senior Member Verified Member ECF Veteran

    Jul 29, 2013
    At 4.2V, a 0.1 ohm resistance will pull 42 amps, well over a Sony US18650VTC3's 30A rating. Even at 3.7V, you're still 7 amps over the limit.

    This is just reckless and plain stupid. Your advice is to just not take long draws? What happens if it misfires in your pants pocket and takes your manhood away?

    0.14 ohms should be the *absolute limit* anyone should be going for with current batteries, and even then, the user should have a deep understanding of his mod, atomizer, and electronics coupled with a safety fuse in case something beyond their control goes wrong.
  12. st0nedpenguin

    st0nedpenguin Moved On Verified Member ECF Veteran

    Jun 24, 2010
    If only somebody made fuses that didn't cut off at ~10a.

    I'm not entirely sure where the idea of not holding the button down for too long comes from though, as long as you're staying within safe specs these batteries can be constantly drained from full to empty without issue.
  13. lctrc

    lctrc Super Member Verified Member ECF Veteran

    Aug 8, 2010
    Just emphasizing the important bit there. "Staying within safe specs" does not mean "do whatever you effing feel like". It means (for example) not exceeding 16 amps constant drain with a 1600mah battery rated for 10C.
  14. Kemosabe

    Kemosabe Vaping Master ECF Veteran

    Sep 21, 2011
    Roe Dylin
    all you need to know is the C-rating of your battery and two simple equations.

    first, get C rating. lets say that its 10. and lets say your mah is 800. (this is what 18350 eFest batts are rated at for example)

    1st equation:

    (C rating x mAh) / 1000

    10 x 800 = 8000 divide that by 1000 and youve got your max amp draw: 8

    2nd equation (ohms law) if you dont know ohms law by now, youre late for dinner.

    fresh battery at 4.2v with 8 amps = 0.525Ω is the lowest you can safely go. and i wouldnt even go that low because eFest is likely over inflating the mAh in the battery.

    as a point of reference, AW 18350s are 700 mAh. thats likely what the eFest are too, but they just feel like inflating to feel special.*

    *the over-inflating guess is my opinion and not based on any real facts, just speculation
  15. Peterdante

    Peterdante Full Member Verified Member

    Aug 28, 2013
    Los Angeles
    i apologize for the ignorant advice. :unsure: i truly do feel bad for saying that.
    but ive learned alot from this thread and i will be more careful myself now.

    as for my buddy he knows its dangerous and has been doing it for a WHILE, he decides to take that risk, being confident he knows what hes doing.
    i guess i was just ignorantly trying to do what he does.

    once again my sincere apologies...
    i would never want to give advice that would lead to someones harm...
    • Like Like x 1
  16. The Yeti

    The Yeti Ultra Member Verified Member ECF Veteran

    Oct 19, 2009
    Black Hills, SD

    Good on ya for seeing the light! Now, get your buddy to see it before he blows off his junk! ;)
  17. Rule62

    Rule62 Vaping Master Verified Member ECF Veteran

    Oct 28, 2011
    Melbourne, Florida
    Good for you! No apology needed. I'm glad you were able to benefit from this thread.
  18. tnt56

    tnt56 Vaping Master Verified Member ECF Veteran

    That's what's so great about ECF. Vapors come together and live, help and most of all LEARN!!!!!!:toast:
  19. damthisisfun

    damthisisfun Ultra Member ECF Veteran

    Aug 6, 2012
    Katy, TX
    Great info - bookmarking - not for sub ohm - not for 1.4ohm coils I am currently making.....
  20. fanatic205

    fanatic205 Senior Member ECF Veteran

    Nov 5, 2012
    birmingham al
    You run the same chance of problems with a 2.4 ohm etc with rebuildables. The exploding battery fairy doesn't magically wave her wand if you happen to excede the amp limit. The way we use batteries would be considered short duration bursts and batteries have a higher burst amperage than the stated continuous amperage.

    You will not be getting 4.2 volts to the atomizer on a freshly charged battery due to some loss from connections. I use AW batts on .3 ohm dual coil genneys and never had a problem.

    Bottom line what ever the resitance is its a rebuildable, you can run into problems regardless. We should all be running safe chemistry batts, and slightly exceeding the continous amperage rating won't magically make the battery explode if you pull over 10amps on a IMR battery.
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