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Interesting info on stacked batteries in regulated mods

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by , 02-05-2014 at 04:23 PM (1085 Views)
please read my comments below which are posts on the subject

Copied from here -

While the quoted post says they tried an aw 3800 mah. I ran the same test with a red efest imr 2000mah. With similar results.

I have 2 Vamos. I set them at 7 watts. I have tested the single 18650 against the stacked 18350 a couple of different ways. My batteries are AW IMR LiMin. The 18650's are 3800 mah and the 18350's are 800 mah. The first way I tested was to put an 18650 in one Vamo and stacked 18350's in the other. Both have a chi forged drip atty and both at 2.2 ohms resistance. I put a #1 on one and a #2 on the other. Placed them side by side and all day went 1,2,1,2,1,2,1,2 etc. Once in a while I would forget which one was next but not often. When it came time to go to bed I checked my notes and found out that I was on my 3rd 18650 and still had the same set of 18350's. All day without changing them. Then I test the 18650 one day and the 18350's for one day. I had changed the 18650 four times for all day. With the 18350's they still had 6.4v(6.2v is low voltage). I am getting well over 60%more vaping time with the stacked setup. Then I wanted to know a little about how this works. It seems that the overhead on a vv/vw is high managing the RMS controller and the voltage booster. With the stacked setup the you have more than enough power to take care of this overhead. With the single 18650 once a great while it would turn off before low volts and I would have to turn it on again and it would change RMS to AV mode. For 2 weeks now, now problems and only have to change batts once a day. In other forums I have read that some people are afraid about melt down and exploding conditions. First: With the Vamo if it were to explode the end cap is designed to blow out away from you and as far as a melt down that gets down to atty's with less than 1.5 ohms resistance. A lot of people don't seem to realise that if you put dual coils of 1.5 ohms your total resistance is .75 ohms, getting real close to a dead short circuit. If you want 1.5 ohms in a dual atty each coil has to be 3 ohms. resistance in parellel devides. Below 1.5 ohms you are doing serious damage to the life span of the battery.......All that said I love stacked batteries.
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Updated 09-08-2014 at 03:26 AM by JeremyR



  1. JeremyR's Avatar
    This matches my experience as well and I'm stacked all the way.
  2. JeremyR's Avatar
    Other posts with info.. My Post Taken from here

    All the talk here is completely relative to the apv your using(amp limit) and the gauge of wire.. Mechs and regulated/vv are completely Different animals

    Quote Originally Posted by N00dl3s View Post
    This was exactly what I've been trying to wrap my head around as well. I'm looking at getting a nice vv/vw mod that will run the right combo of watts/ amps that'll run an 18650 2000mAh the longest between recharges with decent vapor production/taste. I just couldn't figure out which way to go to get there.
    Longest life between charges for you would be an apv that can run stacked 18350s, do it safely, run a 2.8-3 ohm coil. This will last you 2-3 times longer than a single 18650 in the same setup. With my vape style for a full day I would use 2-3 18650 2000mah or one set of stacked 18350s in a regulated mod like zmax. I got 15 hours on one charge in that configuration, would have been 3 18650s

    When running lower ohms like 1.5 you can gain 3- 4 times the battery life with sacked compared to single 18650. For one with stacked batteries you have 2 volts of run time, instead of 1v. Also they can handle more amps so less strain on battery. (Zmax 2.5amps single, 4 amps stacked) Please review my power blog and stacked blog.

    (Only run a lifetime matched set, tested to be within .01-.02.. in an apv designed for it, NOT in an unprotected MECH)

    Of course your right ocelot, same watts less amp draw on battery longer life.
    @ others
    In many cases of vv chips... going below 2.4 ohms nets you no gain in actual watt power only loss. You actually can get less watts and shorter battery life.

    Ie - general vv 2.5 amp limit with one battery. (4 amps with stacked)

    1.5 ohm you max out at 9 watts, 3.7v, 2.5 amp draw.
    3.0 ohm you max at 12 watts, 6v, 2amp draw on battery.
    ~2.4 ohm is the sweet spot, 15watts, 6v, 2.5 amp draw

    I generally find the 3 ohm will get me Double battery life compared to a 1.5ohm and I get 3
    More watts to boot.

    In a zmax stacked batteries get you a 4amp limit and running a 1.5 ohm coil you can really get
    15w and when I use 1.5 in single and stacked mode the stacked mode gets me
    Approximately 3-4 times the battery life.

    Vape on!!
  3. JeremyR's Avatar
    Quote Originally Posted by JeremyR View Post
    Yeah Its nice you still have ~ 6.4v available at cut off instead of 3.2. Much easier for the mod to produce 6v from 6.5 instead of 3.3.

    The really surprising thing was I expected 1500mah from 2 , 750mah batteries. But instead they lasted ~ 60% longer than the 2000mah 650 , which would be ~ 3000+ mah. So it seems when stacking in this you can take the rating and times it by 4. Essentially stacking 800mah 350s should give you comparable to a 3200mah run time instead of 1600mah.

    The reason I think is based on the c rating load being put on them is half of what it would be in single mode.
    More posts taken from v3 thread
  4. JeremyR's Avatar
    Quote Originally Posted by Marty163 View Post
    Thanks for the advice on batteries.

    but as now i am going to purchase more expensive batteries what is everybodys is preferred set up, one 18650 or stacked 18350s.

    ideally i would like to purchase 2 18650 and 4 18350. To try it all out myself.

    Also what are the pros and cons of both configurations?

    Single battery verses stacked batteries.

    18650 induces the boost cuircuit. The mod pulses at 6v peaks. You have 1v of run time, 4.2-3.2 cut off. You get best performance for power and longevity above 2.3 ohms up to 15w. 2.4 ohms @ 15w 2.5amps limit. Below 2.3 ohms you start to lose power as it eclipses the amp limit and the batteries run down faster.

    Stacked batteries induce the buck circuit, which is much more efficient. The mod pulses at 7v peaks. You have 2v of run time 8.4-6.4 cut off. Stacked are best for longevity as they will last 2-3 times longer than a single battery no matter the ohms. Stacked are good for maximum power down to 1.3 ohms . Highest power achieved with 1.5 ohms at 6v for ~ 24w at 4 amps

    You may find the stacked configuration needs to be set a little lower on the power setting to match what your used to in single mode, due to its higher capability and output.

    I have two blogs on power and stacked batteries.

    Why stack, stacked 18350, stacked better
  5. Juvecoop's Avatar
    Where can I read the blog on stacked?
  6. aikanae1's Avatar
    Excellent. Thx for posting this. ^ The other blog post on stacking can be found here;
  7. JeremyR's Avatar
    I have been a strong proponent of stacked batteries for regulated mods capable of it. Like zmax and vamo. I have a sigelie zmax v3 and it is capable of handling stacked batteries. I only recommend stacking safe chemistry imr batteries! There are some major benefits below; but first safety.

    Some of the strict practices and over caution was very true just less than a few years ago. But now with the wide spread use of safe chemistry imr batteries; I think some of this needs to be revisited.

    Aren't laptop batteries stacked 18650's, I recall the were just solder tabbed end to end. Stacked Icr I believe.- And the answer used to be well they don't take high drain loads on the laptop... Well now we have high drain safe chemistry imr batteries to play with.

    Stacking imrs is safer than using a single icr or protected battery. I also think stacked imr in a mod designed for it is also safer than a unprotected mech mod with a single imr, no short protection or cut off .

    You will be fine if you follow some basic simple safety practices.

    a. Yes you should be able to test them with a meter.

    b. The batteries should be a new matched set of safe chemistry batteries; marked and cover with clear tape if you use a marker.

    c. Rotating is good. The top battery will run down .02 v more than the bottom. This should be checked regularly (like once a week) to confirm they are discharging correctly. I don't obsess on rotating it happens enough naturally for me.

    d. You should test the batteries off the charger at this time also to ensure they are both charging to the same voltage.

    e. Since one is .02 lower than the other realize that one will take a little bit longer to charge than the other. Most dual bay chargers are independent bays.

    g. Only use stacked imr batteries in a regulated mod capable of handling it. Not a mech!

    There are some amazing benifits to using stacked batteries in a regulated mod in my experience. Especially above 2.3 amps load or ohms below 2.3.

    1- more power; and being able to reach the stated 4 or 5 amp limit on the device through out the charge. Late model chips are limited with one battery.

    2- longer battery life! I only change batteries once a day now. - *I run one set of efest 18350 IMR - against 3 efest 18650 imr. I get triple the life and double the power on my zmax v3

    a.The buck converters are so much more efficient at stepping down voltage as opposed to the boost converter trying to boost the voltage . = longer battery run time

    b. You have 2 volts of run time! Yes 2 volts run time not one. 8.4-6.4 instead of 4.2-3.2 ... = double the run time

    c. The mod is not stressing itself & the battery to push 6v from 3.7v for instance. You would have 7.2v off the stacked batteries. Easy to push 6 from 7.2. = longer run time and less stress on gear and batteries.

    d. The amp load appears to be split between the two batteries. It's the only way I can explain getting 3 times the life from the stacked configuration. There seems to be much less strain on the battery in the zmax v3. voltage drop isn't such that hey have to be changed before cut off.

    e. With single batteries running high wattage or low ohms you can notice the voltage drop on a regulated mod as the battery runs down. @15w I would have to change around 3.7 -3.6 because it wasn't putting out near 15w anymore. With stacked batteries voltage drop isn't noticeable till near the end of the charge... = you can leave batteries in longer

    g. With a single efest red 18650 2000mah battery in the zmax I get ~2.6 amp limit and cap out on that. I would use at least 3 in a day due to voltage drop pushing it at 15w. With the stacked batteries I can run 4 amps out of the zmax and I do have it maxed out at 1.3 ohms and 6v pushing over 20w. (24w fully charged)

    *I wouldn't even attempt this with a single battery it would be terribly weak. But I run the one set of stacked batteries for 24 hours with this And get 60% more power/ watts out of it.