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How do you measure voltage drop in a mechanical mod?

Discussion in 'Ask The Veterans' started by JaRod, Apr 14, 2014.

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  1. JaRod

    JaRod Senior Member ECF Veteran

    Mar 1, 2014
    Delray Beach FL
    So I've been hearing a lot about voltage drop and how hard this mod hits vs. that, I have many mods, authentic and clones, so I started measuring the voltage with an accurate Fluke multimeter, first I measure the battery voltage using the positive and negative terminals, then I load the same battery into a mod, and measure the voltage again, this time between the center pin (+) and mass (-), I stopped at the 4th mod because I was consistently getting the same voltage reading to .001 volts. SO what am I doing wrong?
    I also tried using the same battery in different mods, clone vs original, silver contact vs copper etc, and I cant notice any difference in how "hard" one hits vs the other....:confused:

    I'll appreciate if you can shed some light on this topic, thank you guys :)
  2. proteckt3d

    proteckt3d Super Member Verified Member ECF Veteran

    Nov 25, 2012
    Your not doing anything wrong, it's just that your were missing an important step, to test voltage with atty attached. So after you you measure the voltage the 2nd time you have to screw the atty to your mod and measure voltage at it's terminals while you fire it ( of course ) and the reading you get is called 'voltage under load' so the difference between load and no-load is your voltage drop.

    There's no need to measure the battery outside the mod because as you see your first two measures gives you pretty much the same result. What would be more interesting to do is to measure battery internal resistance which - in short - shows you how well the battery can hold it's voltage, so the bigger the resistance the faster it will loose it's charge. A new battery should have internal resistance in the range of milliohms such as 0.012 ohms

    voltage drop ( have your wick saturated when you do this )
    battery resistance

    Now for my question, because coil resistance is also a factor here, what is the rule, the lower the resistance the higher the voltage drop? or the higher the resistance the lower the voltage drop?
  3. BuzzKilla

    BuzzKilla Ultra Member Verified Member ECF Veteran

    Nov 4, 2010
    Etobicoke, Ontario
    Voltage drop, how efficient is your mod at transferring the voltage to the coil.

    A few things to note....
    Your atty will affect voltage drop.
    Your mod will affect voltage drop.
    Your battery will affect voltage drop.
    Your coil will affect voltage drop.

    NOW, to find the voltage drop of your mod, all other variables must stay the same... IF they dont stay the same, the test is useless.

    1.take the battery, measure voltage.
    2.assemble everything, measure voltage while firing the coil.
    (doing this on a rebuildable is the easiest. as you can attach the probes directly on the posts...
    3.subtract the two voltage reading, and there you have it.... voltage drop.

    do the test over on a different mod to find out which has less voltage drop.

    *to do it properly all other variables must stay the same!
    ie: atty/coil/battery.
  4. tmcase

    tmcase ECF Guru Verified Member ECF Veteran

    Apr 20, 2011
    Rave's neighbor!
    The easiest way to test voltage drop is with one of these little screw in meters A look at MadVapes' Volt Indicator for e-Cigarettes

    Screw the meter on your mod and jot down the voltage you get, then screw on the atty and test again. Subtract that voltage from the first voltage and you have your voltage drop. If you are testing several mods, use the same battery, and atty. And use a fresh battery to test with.
  5. BuzzKilla

    BuzzKilla Ultra Member Verified Member ECF Veteran

    Nov 4, 2010
    Etobicoke, Ontario
    I would stay away from those voltage testers...

    one of my friends used one to test the V-drop on his CHI v.s. my Gus and Pisces-T and that thing caused a dead short...
    Maybe the boards just couldn't handle the High amp load we were putting it through.

    let's just say batteries were chucked across the room, and mods were dropped... Not fun, not fun at all. :mad:
  6. tmcase

    tmcase ECF Guru Verified Member ECF Veteran

    Apr 20, 2011
    Rave's neighbor!
    I've been using mine for over a year with no problems that's why I recommended that one.
  7. Ryedan

    Ryedan ECF Guru Verified Member ECF Veteran

    Mar 31, 2012
    Ontario, Canada
    You've already got some great info on voltage drop here JaRod. Just wanted to add a post on the subject of 'voltage drop under load' from another forum. It puts things into perspective quite well if you take the time to read it through.
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