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Ohm's law calculator question (+the silly thing I did)

Discussion in 'Sub-Ohm' started by chandco, May 12, 2017.

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  1. chandco

    chandco Full Member Verified Member

    May 8, 2017
    Okay, so. First off, I'm feeling like a dork (that story comes later)*. Now I'm trying to use the steam-engine calculator, and I had a few quick questions (that are probably also dumb, but I do want to make I've got this before I do my first build today).

    So, after being shocked by the results, I figured out that you put your target/max V you'll use into the calculator, not the max V of your battery, correct? (I got something like 800W before I figured that out). And the W the calculator pops out with--that is what would happen with the I/V/R settings (just realized whilst typing this that of course it is... that's how equations work)... which means there's no way to find an actual max wattage without inputting the max voltage of my battery? Yes? (And, clearly, I'm good on that).

    So if I wanted less power than comes out of the calculator with the settings (including an estimated voltage), I just use less power, and my fancy smoking calculator (mod) will just end up using a lower voltage?

    And the actual point of the calculator/using Ohm's Law is solely to determine if the voltage on your battery is sufficient for your build? That's it, right?

    Thanks so much, and please point out anything I got wrong.
     
  2. chandco

    chandco Full Member Verified Member

    May 8, 2017
    STORY ABOUT MY DORKINESS--no more questions


    *Promised story (please take into account that I was extremely tired... but feel free to laugh)

    So, I'm doing my first build today, after the batteries come for my ohm reader. So, I decided it was time for Ohm's Law (again, though E&M was my most hated class in college, so I think I've blocked it from my mind the best I could).

    Good. That's the smart, safe thing to do. I'm feeling responsible, and I paid a fair amount of money for my mod, even used, so I'm feeling confident--this is important, 'cause it's going to go away soon.

    I pop open my mod to look at the battery. Big numbers: 2250 mah, and then blah, blah, blah. Awesome! That's a big number to be working with. (See the problem yet?)

    The calculator runs in amps, no problem, milli => divide by 1000--oh. That's not a big number anymore. But confident in my mod, I proceed, and enter 0.15 ohms, and my amperage, and hit enter. Oh. 0.76W. That seems bad, let's try another... After a few sub ohm calculations, I'm figuring that my mod is the crappiest thing that ever crapped. And wondering where I went wrong.

    Morals of the story: 1) mah is milli-amp-HOURS. Duh. As in, how long your battery can last. Voltage is the shining star of the calculation. 2) I am a huge dork.

    Hopefully that brightened someone's day.
     
  3. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hunterwasser
    I'm thoroughly confused by pretty much everything you wrote.
    Are you using a regulated or a unregulated device, specifically what battery are you using and what are you actually trying to work out?
     
    • Like Like x 2
  4. chandco

    chandco Full Member Verified Member

    May 8, 2017
    Okay, so I guess what I'm trying to ask is:

    Is the only point of using the calculator to determine if your build is safe to use with your battery? Is there anything else I need it for? (If so, none of my other questions matter)

    I'm using a regulated mod with a 2250 mah 11V LiPo battery.
     
  5. petrotech

    petrotech Ultra Member Verified Member ECF Veteran

    Supporting member
    Feb 9, 2015
    indiana
    the calculation for amp draw is different on mechs and regulated. sounds like you were using the wrong one.

    on a regulated device, it's (highest watts you'll use)/(mods cutoff voltage)

    so if you run 25 watts and your cut off voltage is 3.2, the amp draw would be:

    25w/3.2v=7.8125amps (plus a little for chip efficiency)

    I'm doing this from my phone. someone will be by shortly to explain it better I'm sure. lol
     
    • Winner Winner x 1
  6. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hunterwasser
    Rather than an ohms law calculator, I would use use steam-engine to work out the safe amp draw for a resistance or wattage level for a given build/battery.
    Your mod uses an internal LiPo battery, this should be ideal for the requirements of your particular mod. If not then by the sound of it may be swappable. If you can provide the exact model of mod, and the specific model and numbers on the battery then we may be able to do some research.
     
  7. chandco

    chandco Full Member Verified Member

    May 8, 2017
    It's a Mad Modder DNA 200, and the battery is a MaxAmps 2250mah LiPo 11.1v "True 100C"*

    *I don't actually know what the True 100C means, but it's on there
     
  8. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hunterwasser
    I'm not familiar with that mod or Lipo pack, but the DNA chipset is highly regarded. I wouldn't worry too much, the battery should be suitable and the safety features and regulator chip in the mod should take care of the rest. Vape on.
     
    • Agree Agree x 1
  9. MaxximusRevelation

    MaxximusRevelation Senior Member ECF Veteran

    Jul 12, 2016
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