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OHMs Law Help

Discussion in 'New Builders Corner' started by Apprentice15, Jul 16, 2018.

  1. Apprentice15

    Apprentice15 New Member

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    Trying to get into mech mods and cannot for the life of me figure out why a dual 7 wrap with nichrome 80 that reads on a voltmeter to be 2.3 keeps coming out at less than 2 amps? Is it a scewed calculation or is it really that low? I refuse to use it till i figure this out. I will be using fresh VTC5As for batteries unless someone has a better suggestion.
     
  2. KingPin!

    KingPin! In my defence, I was left unsupervised ^^ Staff Member Senior Moderator VU Donator Platinum Contributor Member For 1 Year VU Challenge Team Reviewer

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    Voltage will drop on a battery both under load and over time

    I = V / R
    V = I X R
    R = V / I

    If your voltage says 2.3V don’t use that cell ....you shouldn’t let them drop below 2.8V.... ever (2.5v is the lowest you should go) it’s for this reason most regulated mods cut out around 3v-3.4V because the cells begin to break down resulting in capacity reduction and an increase to their internal resistance
    which could result in a fire hazard and reduced performance

    What’s the resistance of your coil?

    What type of mech are you using? Single Tube, series, parralel?

    What batteries are you using?
     
  3. Apprentice15

    Apprentice15 New Member

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    My apoligies the .23 is the resistance mistype as well as the wrong peice of equipment its fairly late in canada. VT5As for the batteries. Just for clarification the issue i have is two omhs law calculators have an amprage of less than two but it should be between 15-20 amps? Single tube 18650. Volt on the batery is 4 with drop but 4.2 without.
     
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  4. KingPin!

    KingPin! In my defence, I was left unsupervised ^^ Staff Member Senior Moderator VU Donator Platinum Contributor Member For 1 Year VU Challenge Team Reviewer

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    Ahh no probs forgot to say welcome to VU by the way :wave:

    What calculators are you using? They sound wrong

    That resistance and battery is absolutely fine to use on a single battery mech...current draw will be as you say around the 16-20 mark
     
  5. Apprentice15

    Apprentice15 New Member

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    A couple online ones that automatically change all the values when you lock in variables. so you dont have to do all three calculations just need to have the voltage and resistance. Proof that when things look wrong they usually are eh.
     
  6. KingPin!

    KingPin! In my defence, I was left unsupervised ^^ Staff Member Senior Moderator VU Donator Platinum Contributor Member For 1 Year VU Challenge Team Reviewer

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    Indeed maybe try it again without locking in anything other than resistance

    I use this site for coil building the lot (though with coils it’s approximately)

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

    I just checked your inputs ...comes out with correct info
     
  7. Apprentice15

    Apprentice15 New Member

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    Cheers! Any idea why the same setup gives dry hits when the cotton is still damp on a box mod?
     
  8. KingPin!

    KingPin! In my defence, I was left unsupervised ^^ Staff Member Senior Moderator VU Donator Platinum Contributor Member For 1 Year VU Challenge Team Reviewer

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    Did you check for hot spots after mounting the coil? That will burn the cotton inside the coil really quickly gives a funky taste

    When you say damp is it nice and juicy or starting to look a little white in places on the surface after a puff or two ...it’s might to be wicking quickly enough for the speed your vaping

    Airflow hitting the coil can be a problem also

    what set up are you using?
     
  9. Apprentice15

    Apprentice15 New Member

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    Not completely soaked but no dry spots. I've been building for almost two years and this is the first time its ever done this. Its on a v1 goon with one air hole closed off at 90 watts on a drag.
     
  10. KingPin!

    KingPin! In my defence, I was left unsupervised ^^ Staff Member Senior Moderator VU Donator Platinum Contributor Member For 1 Year VU Challenge Team Reviewer

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    Hmm strange mate process of elimination perhaps

    Check leads secured fine
    Is the positive pin lose or dirty
    Are the posts wobbling at all?
    Have you changed wire or retailer recently?
    Coil type?
    Have you change Wicking material or retailer recently?
    Juice change? ...some juices and flavour don’t play well with too much heat

    Could be just not enough wicking and juice and too longer draw
     
  11. Apprentice15

    Apprentice15 New Member

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    All cleaned, posts and leads secure. This is my fist spaced coil would that have any effect?
     
  12. KingPin!

    KingPin! In my defence, I was left unsupervised ^^ Staff Member Senior Moderator VU Donator Platinum Contributor Member For 1 Year VU Challenge Team Reviewer

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    If everything else is the same and that’s the only difference mate perhaps revert back to what you know and see if it’s still there

    I only space my coils if I’m doing temp control or trying to get rid of hot spots on complex coils
     
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  13. KingPin!

    KingPin! In my defence, I was left unsupervised ^^ Staff Member Senior Moderator VU Donator Platinum Contributor Member For 1 Year VU Challenge Team Reviewer

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    Could well be where you have spaced it now airflow isn’t hitting all parts of the coil equally especially where you have closed it down and vaping at 90w ...one side it heating more than the rest of it leading to a dry hit

    Try to centre the airflow on the middle of the coil as well

    Sorry if it sounds like I’m teaching you to suck eggs not sure what you’ve tried or haven’t so covering off everything I can think off :cheers:
     
  14. jwill

    jwill The Great King of Nothing VU Donator Gold Contributor VU Challenge Team Reddit Exile

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    Welcome to VU. Looks like Kingpin has you sorted on the coil and calc, it sounds like you might also need to take a look at your wicking. If you have it too tight the cotton doesn't wick right. At 90 watts it needs to be wicked correctly or it will do as you describe. What is this you are building on?
     

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