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Series regulated, have I been calculating wrong?

Discussion in 'VV/VW APV Discussion' started by Joe Vito, Mar 1, 2018.

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  1. Joe Vito

    Joe Vito Senior Member

    Feb 13, 2018
    so when using ohms law on a regulated dual 18650 series mod, should I be putting in 8.4 for volts on the ohm calculator, or stick with 4.2? And for whatever the answer, why? Thank you.

    Or should I not even be using ohms law for a regulated device. Ugh ‍♂️
     
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  2. Letitia

    Letitia Therion/Nano Junkie ECF Veteran

    Supporting member
    Apr 2, 2017
    West Frankfort, IL
    It's my understanding you should be using watts law. If you are using good batteries and staying within the ohm limits of your mod you don't really need to worry about it.
     
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  3. Joe Vito

    Joe Vito Senior Member

    Feb 13, 2018
    I can’t find anything in the web regarding watts law. I would really appreciate if someone can answer this is great, simple detail.
     
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  4. Beamslider

    Beamslider Vaping Master Verified Member ECF Veteran

    May 29, 2017
    San Francisco
    The mod could be either parallel or series with the batteries. As it is a regulated mod you don't need to do calculations for it.
     
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  5. Joe Vito

    Joe Vito Senior Member

    Feb 13, 2018
    Mooch said in video 3 of minding your mahs that we still need to calculate things
     
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  6. Beamslider

    Beamslider Vaping Master Verified Member ECF Veteran

    May 29, 2017
    San Francisco
    If you are building your own coils you need to measure the ohms on them.

    For a regulated mod, it will fire any coil in its specified range from the manufacturer. Nothing to calculate.

    A regulated mod will refuse to fire a coil it can't fire. even a short will on a regulated mod will just end up with mod not firing and putting a short or such message on the screen.

    What kind of wattage are you trying to use? are you building your own coils?

    You just need to get good amp batteries for the mod. Unless you are using an unregulated mod then just get a couple good 20A batteries like the Samsung 25r and let the mod take care of the math.
     
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  7. Joe Vito

    Joe Vito Senior Member

    Feb 13, 2018
    Let me rephrase everything. Let’s say on a fresh charge on a dual battery series mod, am I always pushing out 8.4, or I’m pushing out depends what my settings are at?

    Like since voltage doubles in a series mod does that mean I’m at 8.4?
     
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  8. Joe Vito

    Joe Vito Senior Member

    Feb 13, 2018
    Okay I think I might have this figured out in my over analyzed head. Please someone confirm if I am correct or not here.

    What I’m thinking is, no, it doesn’t matter that I’m using a series regulated because with a mech, it is pure battery, so I’d be pushing out 8.4 on freshly charged batteries...but with regulated, it doesn’t matter because regardless of if it’s series or not, it’s going to push out whatever I have the watts set at. So if I am using a single battery tube mech for instance (fully charged), and I want to make sure I get that same vape on a regulated device, I just use my ohms law to see what the wattage is, and then set that wattage in my series, or single battery, or triple, whatever mod (because it doesn’t matter) and I’ll be getting the same vape experience that I was on my mech. Please tell me this is correct lol?
     
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  9. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hunterwasser
    Wether it's regulated or unregulated watts is watts. The maths is different for both though.
    With an unregulated series mod yes you calculate using 8.4 volts.

    With a regulated mod series or parallel doesn't matter to the user as it's on the battery side of the regulator chip. The chip draws on this combined pool of voltage to provide the requested wattage on the coil side of the chip. Series is usually used in multi-battery regulated mods as it more efficient.

    So, calculate the amp draw using 4.2 volts, then divide by the number of batteries for your amp draw per battery. Then calculate again for 3.2 volts as the amp draw will be highest at this point.

    Read this -
    sonicbomb's blog | E-Cigarette Forum
    or
    Calculating battery current draw for a regulated mod | E-Cigarette Forum
     
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  10. Joe Vito

    Joe Vito Senior Member

    Feb 13, 2018
    I totally get that, what I’m questioning is, can I use ohms law to see my watts that my mech is using, and then set my regulated device to that wattage with the same atty and build and get the same vape experience? From my understanding you are telling me yes I can, but my concern is weather the fact that the regulated is series makes a difference or plays a role at all in me setting that afore mentioned watts
     
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  11. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hunterwasser
    In principle yes. Mechs are less efficient, so factor that in when doing your initial rough calculations. I would knock off about 20% to allow for battery voltage sag and losses in the mod.
    Then go by what your mouth and lungs are telling you.

    Ultimately it's difficult to directly compare the two as they are different, but you can get in the right ballpark using ohms law.
     
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  12. gpjoe

    gpjoe Ultra Member Verified Member ECF Veteran

    Oct 30, 2013
    Motown
    This. ^^^^^^^

    Don't worry so much. :)

    Do your calculation on the mech and use that as a starting point for wattage on the regulated mod - then adjust as necessary to get the exact vape you desire.
     
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  13. Joe Vito

    Joe Vito Senior Member

    Feb 13, 2018
    Okay thank you guys. So I don’t have to worry that the regulated is in series? I don’t have to worry about doubling the voltage or anything, just simply set the watts to what the mech has them at and knock off about 20%?
     
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  14. VapNMirrors

    VapNMirrors Senior Member ECF Veteran

    Mar 27, 2015
    currently, Earth
    Most regulated mods will also show you the firing voltage. 4.2V x number of batteries in your mech. Even fresh batteries will sag quickly so I'd aim to fire at around 3.8-4V x cells in mech. If you really want to clone the mech experience you could setup a tapered power curve if your mod supports it and try to emulate your batteries firing voltage discharge curve. For that much work, TC is better vape anyway.
     
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  15. Fidola13

    Fidola13 Prepper Verified Member

    Supporting member
    Dec 20, 2017
    Boston
     
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  16. Joe Vito

    Joe Vito Senior Member

    Feb 13, 2018
    Can you Explain these calculations for me in a little more detail please, using example numbers? It would be a great help
     
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  17. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hunterwasser
    As the battery voltage falls, the mod will increase the amp draw to maintain the selected wattage. You need to know the amp draw at full charge, and when the battery is discharged as this value will be the highest. Most regulated mods are about 90% efficient, so you will also need to factor this loss into your calculations as it will marginally increase the amount of amperage pulled from the battery.


    To find the amp draw use I=P/V (-10%)

    Eg.
    60w divided by 4.2v equals 14.3 divided by 0.9 = 15.9 amps
    60w divided by 3.4v equals 17.6 divided by 0.9 = 19.6 amps

    With multi battery devices, simply calculate the amp draw then divide by the number of batteries.

    An 18650 is fully charged at 4.2 volts, and can be considered discharged at around 3.4 volts.
    The voltage that your mod cuts off at will vary depending on make and model. The Smok Alien for instance has a very low cut-off of 2.8 volts, whereas the Noisy Cricket 2 cuts off at 3.5 volts. The best way to ascertain this for your particular device is to run the mod until it cuts off, then put the batteries on a charger. Make note of what voltage they are at, and adjust your calculations accordingly.


    Ohms/Watts Law - Calculating safe amp usage | E-Cigarette Forum


    In a regulated mod it does not matter if the batteries are in series or in parallel, the calculations for amp draw per battery are the same.
     
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  18. medleypat

    medleypat Super Member Verified Member ECF Veteran

    Apr 5, 2016
    Frankfort Indiana
    I think for your mech figure your watts at 3.7 3.8 volts and set your regulated to that watts to start
     
  19. mcclintock

    mcclintock Ultra Member ECF Veteran

    Oct 28, 2014
    Just because the batteries are in series doesn't mean the mod even allows you to set it for 8.4 V. The one I could look said the max. output is 7.5V. It also says the battery voltage range is 6.2-8.4V but doesn't say if it can actually boost voltage or it just quits or sags earlier if you set it that high. As this mod also supports nickel wire, it can expect some serious current at low voltages and better be able to down-convert at great efficiency.

    I think you shouldn't have to calculate anything -- use the cells the manufacturer says to use, etc. .. if they don't give that info, take it back. Actually, the dealer should inform you of the exact specs required when you buy it, so you can get cells for it, but I don't know of even one online site that does. But, if you do calculate it out and something doesn't add up, don't buy it in the first place.
     
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