Series or Parallel? Parallel or Series? What are the Differences in Vaping?

This was asked in a Facebook group by a friend earlier today so I went off on a little bit of a rambling discussion…lol  I had the exact same question a few months back.  I am by no means an expert in battery-related issues – likewise this is by no means the be-all, end-all discussion on the subject, so comments and improvements are quite welcomed.

An 18650 battery is 18mm in diameter, and 65mm tall.  Current is measured in amps (A).  Voltage is measured in watts ( W).  Resistance of coils is measured in ohms (Ω).  I am a sub-ohm vaper – less than 1 ohm of resistance is in pretty much 99.349% of the coils I build and use.  That statistic was made up on the spot, but the ones below were derived using the Ohm’s Law calculator at a website called Steam Engine, found here:

For the most part, I’m comparing a dual 18650 parallel to a dual 18650 series unregulated box mod in this discussion (both with MOSFET-protected switches), and using a very ubiquitous and reliable 20A continuous draw 18650 battery in the examples, the Samsung 25R (20A continuous, 2500 mAh).  It’s not the only battery I use, but I do use them on both series and parallel box mods.  All the devices I vape are unregulated, so I really don’t know much at all about regulated devices.  Both types have the same number of milliwatt hours (mWh) when using the same battery. This rambling discussion is going to avoid stuff like battery sag and voltage drop and use “fully charged” numbers for the sake of simplicity.

If you’re sub-ohm vaping, you really need an ohm reader.  Or two.

1.  Parallel Configuration

Fractured Jaw from Modz By Nasy, Dual 18650 Parallel
A Fractured Jaw from Modz By Nasy sporting a Black CompVape El Cabron RDA, Dual 18650 Parallel Configuration

Dual parallel basically doubles the “headspace” on your continuous amp draw, as well as your battery life (measured in milliamp hours or mAh). If you are running a common battery like a Samsung 25R on a dual parallel 18650 box, you now have 40A to play with, and are dealing with 5000 mAh. You can safely and reliably build down to resistances of 0.11 ohms – at 4.2V that’s a 38A draw (@ appx 160W) – 5 sec draws on that are very very unlikely to vent a properly charged new battery. You get the exact same voltage as you would running one of the same batteries on a mech (tube) mod – whether you have 2 or 27 batteries in parallel, you’re always getting 4.2V out of the system. More mAh at a constant V = longer life out of the batteries as compared to series.

If you like building crazy Clapton coils and shit and are always finding yourself in the 0.1-0.2 ohm range (like me), parallel is probably where you want to be, although pushing all the current through a bunch of wire may yield much longer “ramp-up” times…but that second and third pull off the device will be done with the coils already heated so it will be less of a factor. Most of my parallel builds are 0.1-0.2 ohms and they are very enjoyable. The lower you build, the more spare batteries you need to keep around. You can build around 0.5 ohms on a parallel box (8.4A and 35W) and have a shit-ton of battery life since you are drawing from two cels.

2.  Series Configuration

Fractured Jaw from Modz By Nasy, Dual 18650 Series
A Fractured Jaw from Modz By Nasy sporting a SS CompVape El Cabron RDA, Dual 18650 Series Configuration

Dual series basically doubles the voltage or “force”. If you are running a common battery like a Samsung 25R on a dual series 18650 box, you now have only 20A to play with, and are still dealing with 2500 mAh (just like on a tube). You get the same ratings as are on a single battery – but that “juice” coming out of the battery is not at the 4.2V, it’s at 8.4V. The same 0.11 ohm build discussed above on a dual series setup would be drawing 76A and producing a pretty warm (as compared to the surface of the sun) 641W – way outside the comfort zone of any batteries on the market today. This is less than ideal for most people that like keeping their hands in one piece, so most series builders are comfortable staying at or well above 0.45 ohms.

A build with a 0.45 ohm resistance on a series build produces numbers very much in line with the 0.11 on a parallel – 18.7A and 157W, a very safe build for our aforementioned example 25Rs. Ramp-up times are virtually nonexistent since shoving 8.4V through a coil is a lot easier than pushing 4.2V through one. Most of my series builds are 0.4-0.7 ohms, and they are also very enjoyable. Again here, the lower you build the more batteries you need. You can build around 0.5 ohms on a series box (16.8A and 141W) and have relatively little battery life (as compared to 0.5 ohms on a parallel) since you are drawing from two cels – identically at the same time.  I occasionally run 0.32-0.35 ohm dual Clapton coil setups on series – they have a lot of wire in them so take to series very well and produce a warm (or hot) yet flavorful vape.

Series pushes so much power through the coil that folks often find themselves melting coil legs when dry-firing. It’s much better to “pulse” with short controlled bursts than sitting there with your finger on the button like you can do with a parallel box (and 4.2V).

3.  Closing

Triple Parallel Nasy Box and Dual Series Fractured Jaw
Triple Parallel Nasy Box and Dual Series Fractured Jaw from Modz By Nasy

You can see above that a series box usually has the batteries “reversed” when in the box.  Parallel boxes usually have the batteries facing the same direction.  Both dual setups have the same mWh, it’s the mAh that measures capacity. Both can and do produce very enjoyable vapes.  A triple parallel like above adds even more “headspace” and mAh over a dual parallel for even more safety and battery life.

I’m relatively new to all of this compared to folks that have been sub-ohming for years and years. My advice is that people really actually need both types of unregulated box to truly enjoy a full and wide variety of juices because different flavors taste better at different wattages (and temperatures). I’m pretty happy that I “learned the basics” on mech mods then picked up a parallel box and then got a series. Other folks have different opinions (and some folks throw regulated boxes in their learning progression as well).

Vape on!


Edit:  Some great information from Mike Kelly over at Box Modders on Facebook…

This article has 18 Comments

  1. I have the new rx200 mod using 3 LG he2 coil reads .21 ohm how much head room do I have at 80 watts

  2. man, i dont know all about this, im just vaping and vaping, im using diablo box mod and rda and 24g kanthal, it is parallel, i dont know about all the discussion here, i dont know about resistance and whatsoever, can anyone help me please? i will really appreciate it, because im planning to change my box mod to dos vape or i dont know about models of dos vape and pairing it with air master RDA, somehow it expensive but i will buy it, so for cloud chasing vape, can anyone recommend me a vape set that extremely releases vapor? please gents, thanks

    1. Absolutely, if someone here can’t help we can certainly get you steered in the right direction. In general, folks seem to be after large amounts of vapor (cloud chasers) which usually requires lots of airflow or after a very full flavor experience (flavor chasers) which usually requires a smaller chamber and less airflow. Most of my RDAs like the El Cabron and Twisted Messes can easily do both – it’s all in the coils that are used.

      Most of the cloud chasers I know certainly use 24g or bigger (22g, 20g) wire, so you’re on the right track there I think. Generally, smaller gauges like 28g and 30g produce more “crisp” notes in the flavor but have less surface area so produce less vapor overall.

      All that being said, if you have a parallel boxmod and a good set of 20A continuous amp drain batteries (like a 25R or HG2), you can certainly build very safely as low as 0.15-0.2 ohms (0.15 ohms is a 28A draw across the two 20A capable batteries wired in parallel – easily capable of 30A or more). I would start with something like 6 wraps of 24g KA1 around a 3mm rod, and dual-coil. That should put you right at 0.3 ohms…if you think you need a warmer and more vapor producing vape, dropping to 5 wraps is around 0.24 ohms – well within the safe zone.

      You can do this sort of thing with a lot of different RDAs – from the very low end authentic like the Wotofo Troll (25+USD) – to the higher end like the authentic Velocity RDA (100+USD), with all sorts of replica and clone products in between. You don’t need to spend a boatload to chase clouds anymore – with a 200W boxmod like the Reuleaux RX200 selling at or under 50USD, you can easily be subohming with a mod, rda/rta, batteries and a charger for 100USD these days…:)

  3. NO mosfets there? what about the button?

    1. Most of my boxes have MOSFET-protected switches, yes. I would highly recommend those for beginners for sure. I do have a couple of boxmods that fire somewhat mechanically, but the chance of venting a battery is always higher with those. I skipped most of that discussion in this but it’s definitely a great topic for another post.

  4. This is an old post but I have to say this because it is a common mistake and completely misleading. Battery life is the same in both configurations. It is affected only by the Power(Watts) that you draw. In parallel configuration you have doubled the Amperage and in series doubled the Voltage, so the power that you use is the same. W=V2A=2VA

    1. Agree, I think I make the point that mWh is exactly the same in both configurations – “Both types have the same number of milliwatt hours (mWh) when using the same battery.”

      The number (and type, generally) of “puffs”” one sees out of both devices is wildly different because folks aren’t drawing the same A out of the same batteries with the two types of device. I draw a lot more more amps out of my batteries when I’m vaping parallel usually than when I’m vaping series.

  5. Well done, I use a regulated box, iStick 100w with a Kanger Sub Tank. It’s prebuilt to be 0.5ohms but my mod reads it at 0.63 lol. I do use the Samsung 25R batteries and the mod IS IN parallel. I can adjust the voltage all I want, so normally I vape tough at 5.4v… So with 20A continuous at 2500mah, I’m really at 40A at 5000mah.
    0.63ohms/5.4v = 8.6A.
    40-8.6 = 31.6A

    I have 31.6 amps left of head room to draw before I blow up my hand and face. I do use an occasional dripper for my “show off” clouds at 0.3… That’s drawing 18A… I still have 22A headroom on 5.4v. My boxmod will start to “warm” up on that amperage bit not “hot”. I last 2 days on 5000mah at .63ohms… It’s my sweet spot, 50/50 juice, stays nice and cool and gets great flavor and a nice cloud. My dripper build is just too warm of a throat hit for me, especially on a series battery Sigelei, that thing is explosive, as it only took 2sec to draw a warm and fat cloud. But yea anyone who’s read this article should consider the pros and cons of parallel and series battery layouts. I personally prefer parallel. It’s only safer, it lasts longer, and it doesn’t make a difference in flavor and cloud depending on the build you do. Remember vaping ohms law people, in vaping Max amperage of the battery DOES NOT MATTER. It’s the continuous amp that matters. Maximum only happens for < .5 seconds of hitting that firing button. Don’t be a statistic and make us educated and safe vapers look bad. Happy vaping!

  6. You state that:
    “Dual series basically doubles the voltage or “power””. This is correct and incorrect, while you’re doubling the voltage you’re not necessarily doing the same for “power” which is measured by wattage. It seems that you’re equating the two when they are separate and distinct measurements.

    1. It’s a bad choice of words, I agree. I was trying to simplify for the lay audience. Still scratching my head over the best way to verbalize what I’m trying to describe there.

    2. And voltage is measured in volts… The power produced when applying voltage to a given resistance is wattage… Inr batteries sag so hard that saying your getting 160 watts out of a .11 ohm build on 4.2 volts is nowhere near close… Even on a parallel box you’d get no where near that.. Achieving the same wattage from 2 cells will yield the same battery life be them in series or parralel… Inr batteries do not violently explode… Period… Lipo batteries are capable of massive amp loads you say no batteries are… However when they fail… It can be violent… From reading your piece you sound like you almost have a basic understanding of what’s going on… But almost every statement had something wrong with it

      -one of those years and years guys

    3. And I’m not trying to be a dick… You don’t need to approve my comments… But editing your article after you do your research would be appreciated… Your representing our community and anyone with any electrical knowledge or training would have blown you off in the second sentence

    4. This is one of the reasons I am pondering walking away from the vaping community, to be honest. Obviously my audience was and remained new vapers. I was a new vaper at one point, and honestly there was no information out there anywhere for someone like me. I appreciate your perspective, I certainly appreciate your comments. But where were you when I was getting started?

      It’s nice to see that once I produced some content that was (ad is) actually helping folks (this remains the most popular post on my blog and has well over 500+ hits weekly), you can finally find your voice.

      I am really sick of know-it-all vapers, vape businesses who are just out to make $ off the back of people trying to quit smoking and save their lives. I know everything I will ever need to know about vaping at this point. I can make my own devices, make my own juice, make my own coils, and I have a great relationship with an actual cotton farmer. It’s not like I’m worried about the regulations the FDA is about to shove up all of our asses…lol. Why would I care about that? So many advocates just seem like they’re here to improve their profile and profit off vapers as well.

      Zac. I have struggled with how to reply to this comment for months now. I’d rather have an ally than make another enemy. You certainly know what you’re talking about.

      If I asked you to come here and edit these for me (and receive full credit) – is that something you would be able to do in order to help us all? I’d love to know what you think about our community. I’d love to know where you think the industry is going. I’d love to hear what your favorite recipes are and how you got started in this wonderful community.

      Thank you – your comments are getting approved because they were spot-on. I had other stuff going on. I still do. All I was trying to do was help, and I’m still committed to doing that.

      Would you give me (and our whole vapesphere) a hand please, good sir?

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  8. Reblogged this on theeffectsofsmoking and commented:
    This is the only thing that really gets me annoyed! I mean what the hell does that mean?? I need a technical guidebook on exactly what the hell half of these slangs are!! Im going to try and find a guide! LOL

    1. LOL… I’d be happy to take a stab at explaining any of it. We should come up with a list of terms and I’d be happy to get that up as another post today. I’m pretty immersed in the jargon so it tends to fly by without noticing, alas…sigh.

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