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advanced batt question

Discussion in 'Rebuildable Atomizer Systems' started by scabbytattoo, Nov 22, 2013.

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  1. scabbytattoo

    scabbytattoo Super Member Verified Member ECF Veteran

    Nov 18, 2012
    pensacola
    So I was sitting here thinking about amp draw in regards to sub-ohm. So here is the set up....... .4-.5 ohm with a fresh battery. So for amps it's something like 4.2v/.4ohm= 10.5 amp draw. Now here is my question when calculating amp draw do I go by what the battery voltage or the voltage under load (re: what it would read with an inline meter under the .4 ohm load) any one has any info I'd be glade to hear it.
     
  2. Jazzi Mike

    Jazzi Mike Ultra Member Verified Member ECF Veteran

    Jun 3, 2013
    Michigan
    While, 10 amps is the limit on most of the decent batteries, it is not something I would experiment with. You really should go above 8 amps with a batt that has a 10 amp limit.

    While it is true you are probably not getting the full 4.2 volts to your atty, you should just buy batteries with higher amp limits, rather than pushing the ones you already have.

    Lastly, is the vape at .4 ohms that much better than .6? Srsly...
     
  3. scabbytattoo

    scabbytattoo Super Member Verified Member ECF Veteran

    Nov 18, 2012
    pensacola
    Thanks for the input. So what I get from what you are saying is, that you indeed measure from what is going to the Atty? Also for the way I like to vape (about 1/2 second rips) at .4 if get an instant response. Where at .6 it takes that 1/2 second to get going. I know it sounds like splitting hairs but it's just how I like to vape. To each his own. But again thanks for the info.
     
  4. scabbytattoo

    scabbytattoo Super Member Verified Member ECF Veteran

    Nov 18, 2012
    pensacola
    Oh thought I should add I'm already using mnke batts. So it's not a safty issue I know I'm vaping safe this is just a curiosity.
     
  5. pdib

    pdib Registered Supplier - Offline ECF Veteran

    Nov 23, 2012
    Hey, scabs. You want to use the full battery voltage. Although you lose voltage to your mod (v-drop), you are still asking the battery for it, just not vaping it.
     
  6. scabbytattoo

    scabbytattoo Super Member Verified Member ECF Veteran

    Nov 18, 2012
    pensacola
    Sweet. So far that's how I've been doing my math just to be on the safe side. I'll never do a .2 coil (unless I feel frisky and do a quad coil on the Helios) so I shouldn't ever come close to the Max amp of my battery. Thanks for the answer. I hate it when I don't know something I think I should lol!
     
  7. Krazirob

    Krazirob Super Member Verified Member ECF Veteran

    Sep 12, 2010
    Cameron, NC
    there is going to be V drop in whatever MOD you use.....a fully charged battery on my mod puts out 3.6V and 3.9 on another......but to be safe get some good batteries....

    AW IMR
    18650 1600mah 24A

    MNKE IMR
    18650 1500mah ​20A

    Orbtronic
    18650 SX22 (hybrid) 2000mAh 22A

    Samsung hybrid
    INR18650-20R 2000mah 22A

    Sanyo hybrid
    UR18650EX 2000mAh 20A

    Sony
    us18650vct3 (hybrid) 1600mAh 30A

    EH IMR
    18650 2000 mAh 16A
    18650 1500 mAh 22A

    Efest IMR
    18650 1600mAh 30A

    just in case you have these as well and didn't know the specs.....sorry if you did already........


    AW IMR
    18650 2000mah 10Amp CDR
    18490 (1100mah) 8.8A (16.5A?)
    18350 ​(700mah) 6A


    Panasonic ​or Orbtronic hybrid
    CGR18650CH (IMR/hybrid) 2250mAh 10A
    NCR18650PF (LiNiCOMnO2) INR/ICR/IMR Hybrid 2900mAh 10A
    NCR18650PD (LiNiCoAl) 2900mAh 10A


    Samsung hybrid (LiNiCoMnP)
    INR18650-22P 2200mAh 10A


    Sony
    us18650v3 IMR 2250mAh 10A


    EH IMR
    18650 2000 mAh 16A
    18500 1100 mAh 8.8A
    18350 800 mAh 6.4A


    Efest IMR
    18650 (IMR/hybrid) 2250mAh 10A
    18650 2000mAh 10A
    18490 1100mah 8.8A
    18350 800mah 6.4A
     
  8. pdib

    pdib Registered Supplier - Offline ECF Veteran

    Nov 23, 2012
    Nice info, Krazirob, buyer of Grands when wife looks at you funny (I'na hafta try that sometime). This one tests out at more like 7A.
     
  9. Krazirob

    Krazirob Super Member Verified Member ECF Veteran

    Sep 12, 2010
    Cameron, NC
    thanks....ill change that then for my records....i tend to stay away from the bottom list......i rather have a battery capable of more power than not enough.....especially since i use them on sub ohm coils as well as 1.1 - 1.3 coils.....

    Yeah she looked at my even more funny when i had two packages arrive......lol......so ill be taking a trip to the coach store this weekend......HAHA
     
  10. Rader2146

    Rader2146 Ultra Member Verified Member ECF Veteran

    Mar 11, 2012
    Waco, TX
    I get the reasoning behind the safety "buffer" of figuring current using 4.2V, but I wholly disagree with that method. I've always been an advocate that you should know exactly what is happening in you mod. That method is OK if you you are trying to figure out what resistance would be in the "safe" range, but if it's already built you should know with a reasonable measure of accuracy how it is performing.

    For that reason....to ACCURATELY calculate the current demand from the battery you should measure the voltage at the atty posts and divide that by your coil resistance. Once you know the true current, you can adjust to suit your balance of safety and performance.
     
  11. pdib

    pdib Registered Supplier - Offline ECF Veteran

    Nov 23, 2012
    Really? I had surmised, from my own experiments, that the voltage measured at the atty posts wasn't necessarily indicative of what was being drawn from the battery. When I made improvements to my device, was I not getting rid of unwanted "resistance" that was wasting some of the current? I thought that v-drop (as separate from battery's internal resistance) was indicative of current being drawn but not getting to the atty. Thanks for any clarification, Rader.

    As for 4.2, well I figure it at my actual charge level.
     
  12. scabbytattoo

    scabbytattoo Super Member Verified Member ECF Veteran

    Nov 18, 2012
    pensacola
    Nice numbers @krazirob!

    @rader from what I understand about what your saying is.....an in line meter under load isn't fully accurate? And btw I love it to find other people to be as nit picky about e-cigs as I am.
     
  13. Rader2146

    Rader2146 Ultra Member Verified Member ECF Veteran

    Mar 11, 2012
    Waco, TX
    You were getting rid of unwanted resistance, but it wasn't nessisarily wasting current. Wasting power...yes. The current is just reduced due the the unwanted resistance. Current supplied by the battery is dependent on the total resisistance of the complete circuit, and the circuit can be divided into: Battery resistance, material and contact resistance (mod and atty), and coil resistance. Eliminate some of the contact resistance and you increase the current through the circuit and decrease the voltage drop.

    Here's a spreadsheet that might help...

    https://www.dropbox.com/s/rqvj5anfq1cg1ia/V%20Drop%20Calc.xlsx
    An inline meter can get you close, but I don't like them because they are also adding resistance to the total circuit. Meaning that the current through the circuit without the meter will be HIGHER than what you calculate with the meter.
     
  14. gingersnaps

    gingersnaps Super Member Verified Member ECF Veteran

    Aug 3, 2010
    everywhere
    The efest 18650 2000 mah info is wrong. I keep seeing people post it as a 10a but when I do the math i come up with 20 amp. So to be absolutely sure i emailed efest to get the specs direct from them. Here is the response

    Thanks for your kind enquiry. This is Kiko from Efest company.

    For Efest IMR 18650 2000mah battery, the C rating is 10C. Max discharge rating is 20A.
    Hope help you know more about our products :)

    If you have any other questions, feel free to let me know.

    Best regards,

    Kiko
     
  15. gingersnaps

    gingersnaps Super Member Verified Member ECF Veteran

    Aug 3, 2010
    everywhere
    Sry but it has been irritating me to keep seeing bad info repeated.
     
  16. scabbytattoo

    scabbytattoo Super Member Verified Member ECF Veteran

    Nov 18, 2012
    pensacola
    So just for fun today I'm going to meter at the posts to see what i get. Still want an in line just for ghit & shiggles. Thanks for all the input guys, im getting into higher end mechs and wanna see if all the diffrent contacts really do makeuch of a difference
     
  17. Rader2146

    Rader2146 Ultra Member Verified Member ECF Veteran

    Mar 11, 2012
    Waco, TX
    Take 2 measurements at the posts. One with the inline meter on and one without. Compare the difference. You can also compare similtanious readings of the inline meter vs the posts.
     
  18. scabbytattoo

    scabbytattoo Super Member Verified Member ECF Veteran

    Nov 18, 2012
    pensacola
    lol I'm never going to get anything done at work today playing with my new Cronus.......
     
  19. dr g

    dr g Moved On ECF Veteran

    Mar 12, 2012
    Paradise
    Better is subjective but the difference between .4 and .6 ohm on an unregulated mod is profound. That's upwards of a 50% difference in power at vaping voltages.
     
  20. Krizzell

    Krizzell Super Member ECF Veteran

    Aug 20, 2013
    Las Vegas
    Just build the ohms higher....again do you have to vape at .4? Just to do it...
     
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