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**Sub-Ohm Vaping** Discussion, Safety, Battery Info, & Warnings

Discussion in 'Sub-Ohm' started by Technonut, Sep 8, 2013.

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  1. BecknCO

    BecknCO Senior Member Verified Member ECF Veteran

    Nov 26, 2013
    Denver, CO
    I just got a nemesis clone, a voltmeter/ohmmeter, a pair of sony vtc4's, and a couple of Igo drippers in classifieds. On the Igo W I bought, the guy built a .4ohm dual coil. So this sub-ohming thing is probably not for me. I don't care to blow huge clouds, and just want to taste my juices better. Nevertheless, I had to give it a shot.

    When I first loaded everything up, I checked the battery in the nemesis and under load it was reading 4.28v. This could be due to the crappy charger I'm using from my sigelei zmax kit, so I have a nitecore i4 v2 in the mail. When I put the Igo on and fired it up, it was far too much intensity and heat for me. Now that the battery is down near 3.88v, it's a little more manageable, but I'm not sure if I can get better flavor by building a coil or set of coils with higher resistance. I'll experiment with that, but was wondering what you all have found to be as the sweet spot that gears more towards accurate flavor.

    The only safety question I have is - at what point should I change the battery? I have read 3.6, and I know the sony's can go down to 2.5 but that isn't smart, so at what voltage should I change the battery?
  2. xpen

    xpen Super Member ECF Veteran

    Jun 18, 2012
    4.28V under load is way too much, you should read 4.23 or thereabouts w/o load at max.. I'm wondering if your meter is accurate. Since you've already ordered a Nitecore, I won't preach to the choir ;-)

    IMR batteries can tolerate being discharged to 2.8V - some even lower than that - but common recommendation is not going lower than 3.2V.

    On the other hand there's little point in going that lower with a mech mod, you normally replace the battery by 3.7V..

    Considering you didn't like your vape with a fully charged battery, yes I think you should probably aim for higher ohms.

    Give a try to the microcoils, if you haven't yet: thread is here
  3. xpen

    xpen Super Member ECF Veteran

    Jun 18, 2012
    Accurate flavor depends on a lot of factors (some of them highly subjective btw): as a thumb rule, sweet/fruity flavors may benefit from relatively lower wattage - say less than 12W or so - while tobacco flavors can go much higher and still be good.

    W = V squared / Resistance
    Example: 4V applied to a 1.0 ohm resistance generate 16W

    So on a mech you should tune your coil resistance for the maximum wattage you want to achieve (with a freshly charged battery), then swap batteries when their voltage can't produce any more a satisfactory vape.
  4. RagingDuck

    RagingDuck Full Member

    Jan 10, 2013
    Okay Noob here doing research all day. I have a Patriot and Nemesis with Sony US18650VTC4 2100mAh, and resistance meter coming in along with some 24 gauge Kenthal. Here's my question:

    Even in this very thread I am getting conflicting information about the voltage on these batteries. I want to be a safe as possible, so can anyone clarify my "math"?

    With a C rating of 14.2 for the Sony US18650VTC4, max continuous discharge is 29.82 amps correct?
    So as long as I stay well under 29.82 amps, watch my battery temps, and check my resistance I should be in the "safe zone"?

    What is the true Voltage of this battery? From what I gather, it's 4.2 fully charged and as low as 2.something, but that I should not let it go below 3.2 (being on the safe side). For safety's sake, should I be using 4.2 as my voltage when calculating what resistance is safe?

    Also wanted to clarify: besides shorts in my coil build, the major contributing factors to thermal runaway is:

    -Going over the max amp draw for your battery.
    -Letting your battery discharge below a certain amount as to damage it. If so, what is that amount?
  5. BecknCO

    BecknCO Senior Member Verified Member ECF Veteran

    Nov 26, 2013
    Denver, CO
    Thanks! That clears up a lot for me. I think the sony vtc4's say they can go down to 2.5v, but you're right - there would be no point if you're seeking the higher wattages in sub-ohming. I'll make sure to change them out around the 3.7v range. I can't figure out which is at fault - the voltmeter ( I have this one iSmoka Digital Ohmmeter & Voltmeter - 101 Vape ), or that the PoS Sigelei charger is over charging them. I'm hoping it's the latter, since the nitecore came today. The nice guy I bought the IGO W from said he made the coils at .4, and the meter reads .43-.44 every time I check it, so at least that part's working. I'll give it a shot and see tomorrow/today. I also plan to give the micro-coils a shot when the 28 guage kanthal arrives and I set up my KL+ clone for the first time. :)

    Oh wait - when I say under load, I mean I am literally attaching the mod to the voltage reader 510 pin and hitting the fire button - are you saying it should read in the 4.23 range on a freshly charged battery when doing it this way? This is the way I'm doing it, and getting the 4.28 reading, and with the voltage drop, I'm guessing the battery is actually like 4.3 then which is a little scary, but I did clean the crap out of the mod including the contacts and the batteries are only 2 days old

    Thanks for this as well. Lately, I've really only been vaping NETs in this dual coil setup (Huntsman, and Dover Court), and while they taste pretty good, I think it's the heat that might be a little too much for me. I thought that might be the case, so I used the tatroe cap on the IGO W and used a drip tip that has a delrin/plastic base. It's still pretty intense - I'm not sure how you guys handle it, but I must say the clouds are abundant! I bet a single coil around .8 would be a good next build to try. Since I vape mostly nets, and really bought the drippers for aro tobaccos - what wattage do you shoot for with those?
  6. xpen

    xpen Super Member ECF Veteran

    Jun 18, 2012
    sorry I feel we're quite off-topic now, so I'm going to keep it short..

    You should read 4.23V or very close to that at maximum from a charged battery without any load. So yes 4.28V under load is way too much, retest after (discharging some, and) recharging with the Nitecore, it should be definitely lower than that.
  7. Nic-O-Fiend

    Nic-O-Fiend Moved On

    Jan 20, 2014
    4 setups and still getting a 0.2ohm read, I want 0.8 to 1.0, what am I doing wrong, got a 5/6 wrap of 25g kanthal
  8. Whiskey River

    Whiskey River Full Member

    Sep 17, 2013
    Give it more wraps or get some 28-30g kanthal
  9. Nic-O-Fiend

    Nic-O-Fiend Moved On

    Jan 20, 2014
    omhs meter keeps running at 0.2omhs and jumps to 0.4 with all my builds, is something wrong with the meter?

    did a 7/8 wrap of 28g and still getting a 0.2ohm read that's jumping indicating a short? just want to understand sub ohms a bit better in terms of wraps/gauge - ohms and really want to know if I got a shtty ohms reader
  10. Killjoy1

    Killjoy1 Ω Destroyer Verified Member ECF Veteran

    Aug 15, 2011
    New Hampshire, US
    Sounds like it's either your meter is bad or your builds are shorting somewhere. Take a close look at your build and make sure you don't have any coil wraps that are touching the posts. For checking the meter, take two different lengths of wire, not wrapped coils just straight lengths of wire, and meter them to see what you get. If they are both reading the same, then likely there is a problem with your meter
  11. wedoitall

    wedoitall Super Member Verified Member ECF Veteran

    Very very good info. Thanks .

    Sent from my iPhone using Tapatalk
  12. SonHouse

    SonHouse Vaping Master Verified Member ECF Veteran

    Jul 7, 2013
    Can you comment on what assumptions are being made to determine what a "safe" Ohm resistance is?
  13. Killjoy1

    Killjoy1 Ω Destroyer Verified Member ECF Veteran

    Aug 15, 2011
    New Hampshire, US
    It's pretty simple, really :)

    "Safe" resistance is determined by how many amps would be drawn from the battery versus what the safe discharge rate of the battery is. Every battery is rated for a maximum discharge current and going above that would not be considered "safe", so the safe resistance field is the lowest you can go without going over that amp limit on a fully charged battery
  14. SonHouse

    SonHouse Vaping Master Verified Member ECF Veteran

    Jul 7, 2013
    Yeah, you'd think that but that's not what this chart shows for instance, for a battery rated at 10 amps of draw, they're listing a coil with 8.3 amps of draw. I'd like an explanation of the assumptions being used to determine what 'safe' is.
  15. Mr.Mann

    Mr.Mann ECF Guru Verified Member ECF Veteran

    Supporting member
    Dec 30, 2011
    All over the place
    Maybe just a little bit of headroom?
  16. Killjoy1

    Killjoy1 Ω Destroyer Verified Member ECF Veteran

    Aug 15, 2011
    New Hampshire, US
    Ah, I see. I misunderstood your question. Not sure who best could answer that definitively

    The only assumption I could make would be what MrMann posted above. Since batteries' internal resistance will change as they age, so will their safe discharge limits. It makes sense when talking about "safe" coils that that would be taken into account. Hard to give concrete "safe" numbers in this case since there are no hard numbers for degradation of battery limits that would apply to every circumstance
  17. SonHouse

    SonHouse Vaping Master Verified Member ECF Veteran

    Jul 7, 2013
    Generally the use of apostrophes around a term such as safe means it's been defined. I would assume TechnoNut knows where he got this graphic and can add that information.
  18. sawlight

    sawlight Vaping Master Verified Member ECF Veteran

    Nov 2, 2009
    There is no hard number for this as this is still all new. I think allowing 20% to the max discharge is a good practice. Others seem to think they need to push it to burst capacity as they are "pulsing" rather than having long term use.
    I tend to err on the side of safety, others don't! I saw a build last night of .06 ohms with a 30A battery, 60A burst! No way I'd use it, or even suggest anyone use it, but so far it hasn't blown up, to my knowledge.
    There's still a lot of "gray area", hence the quotation marks, and many of us would rather not read about others in the news papers!
  19. EddardinWinter

    EddardinWinter The Philosopher Who Rides Verified Member ECF Veteran

    Jun 13, 2012
    Richmond, Va
    Be careful, there are posters that will label you as an "alarmist" and "a shill for regulated mods" if you talk about battery safety.

    I, on the other hand, agree that I wanna be safely (minimum 10% lower) on my atty draw than battery rating. High quality, safe batteries are not prohibitively expensive, so why court disaster?

    Thanks, Techno, for that chart and all you have taught me about batteries!

    Roaring thunderously via Tapatalk...
  20. B1sh0p

    B1sh0p Super Member Verified Member ECF Veteran

    Aug 30, 2013
    image.jpg ...........

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