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Parallel Mech

Discussion in 'New Members Forum' started by Cloudboi325, Sep 16, 2018 at 11:16 AM.

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  1. Cloudboi325

    Cloudboi325 New Member

    So I've read up and I just wanna make sure I got this right. If you use a series mod, your voltage doubles. So a 3.7V in series with another 3.7V battery, it adds up to 7.4V and nothing else changes. But in parallel you mAh and Amperage doubles. So a 1500mAh 30CDR battery in parallel with another of the same specifications would be 3000mAh and 60 Amps, therefore I could safely run a .11 ohm build on my mod. Correct?
  2. classwife

    classwife Admin
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  3. bombastinator

    bombastinator Vaping Master Verified Member ECF Veteran

    Sep 12, 2010
    MN USA
    You could run it in series. Parallel might be more of a problem
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  4. bombastinator

    bombastinator Vaping Master Verified Member ECF Veteran

    Sep 12, 2010
    MN USA
    I hate it when people just mark “disagree” without explanation. I don’t mind being wrong, but I would like to know HOW I am wrong
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  5. Doffy

    Doffy Vaping Master Verified Member ECF Veteran

    Supporting member
    Mar 15, 2014
    Screenshot_20180916-220734.png Screenshot_20180916-220544.png

    Top is parallel, bottom is series.

    OP, i wouldn't trust double the amps from a parallel mech. Mainly because contacts get grimy quick, leading to uneven draining. But you can go higher amp draw than a single battery.
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  6. bombastinator

    bombastinator Vaping Master Verified Member ECF Veteran

    Sep 12, 2010
    MN USA
    Fair enough
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  7. r055co

    r055co Ultra Member Verified Member ECF Veteran

    Dec 24, 2015
    What I do is take 10% off, so for 2x Samsung 20S @ 30A = 60A I put my max Amps at 54A for parallel
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  8. Shawn Hoefer

    Shawn Hoefer ECF Guru Verified Member ECF Veteran

    Jan 21, 2015
    Arkansas Ozarks
    On paper, you'd be correct. In practice, there are going to be issues. It's best to leave a margin for safety.

    In parallel:
    1. Base your calculations on the batteries' full charge of 4.2V rather than the nominal 3.7V

    2. Figure 1.5 x Amps (with a 30 Amp cell, 45 Amps... 20 A = 30 A and so on).

    In series:
    1. Base voltage on 8.4V, not 7.4V

    2. Base current on about .8 CDR (30 A = 24 A, etc)

    IN ALL CASES ensure that you're practicing safe battery handling... Make sure that the cells are in good condition (no tears or nicks in the wrappers... No dents or dings), make sure you're using quality authentic cells from a reliable source (60 A 4000 mAh eBay cells are not right...). Clean contacts will help...
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  9. r055co

    r055co Ultra Member Verified Member ECF Veteran

    Dec 24, 2015
    Let me add to my above post, for Newbies with Mech's I always recommend full amps + 1/2 amps of second. So for 2x 30A = 60A I would recommend to Newb's max Amp ceiling of 45A. That is until they get some experience under their belt, they need a lot more wiggle room IMO.
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  10. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hunterwasser
    Great advice so far.

    Something else to consider when choosing between dual battery series or parallel, is that assuming you use an appropriate resistance coil you end up in the same place. Two batteries contain a pool of watt hours.

    Series - voltages are added together, same mAh same amp limit
    Parallel - voltage the same, but mAh and CDR added together(ish)

    Exotic coils like multi-core claptons that use a lot of metal and therefore end up being very low resistance. These are better suited to a parallel mod where you have a large combined amp pool.
    However, the higher the current in an electrical circuit is the greater the losses will be, ie the more voltage drop you see in the mod which increases exponentially with amp draw.

    Because series configuration has a higher voltage pool, much higher resistance coils can be used comprised of thinner wire which is intrinsically more efficient and ramps up/down faster. Less current in the circuit will be more efficient. Less current also means less battery voltage sag.

    Ultimately assuming you choose your coil resistance sensibly, you can use either parallel or series to achieve the same output wattage and approximately the same run-time from a pair of batteries, though series is more efficient.

    Series - 0.7 ohms @ 8.4 volts = 12 amps and 100 watts
    Parallel - 0.175 ohms @ 4.2 volts = 24 amps and 100 watts
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  11. untar

    untar Ultra Member

    Feb 7, 2018
    One last thing:
    A parallel mech reacts much worse to batteries inserted the wrong way (essentially shorting both batteries). Unfortunately that wrong way is how batteries are normally inserted in regulated mods (and some series mech boxes) so it's easy to make that error when not paying attention.
    I've seen some homemade parallel mechs a few years ago when overall power was lower, they had a fuse to prevent that short from happening. I don't think commercial parallel mechs have those (I remember seeing pictures on this forum from an accident involving a parallel mech where one battery was inserted upside down a few months ago).
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  12. Zaryk

    Zaryk Ultra Member Verified Member

    Jan 25, 2018
    Series should be 8.4v and parallel should be 4.2v. Just trying to keep the confusion down here, so the names are just flipped, the numbers are correct.
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  13. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hunterwasser
    Jeeze, sorry guys. Corrected.
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  14. BrotherBob

    BrotherBob Vaping Master ECF Veteran

    Dec 24, 2014
    Welcome and glad you joined.
    I have provided a little more information which might help understanding batteries.
    Might like to read:
    Calculating battery current draw for a regulated mod | E-Cigarette Forum
    Index | E-Cigarette Forum
    Battery Safety: Will You Marry Me? - Mt Baker Vapor
    A Guide to Safe Charging - The Complete Guide to E-Cig Safety
    Vaping 101: Battery Safety
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