how low can you go

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Susan~S

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What battery are you using? Not all batteries marked 30A are 30A CDR.

Everyone is free to set their own parameters, and I can only say what mine are.

I try to never exceed 50% of the CDR (continuous discharge rating) of a fully charged battery (4.2v). So with a 30A battery, that would be 15A. This Ohm's Law Calculator tells me that a .28 ohm build is as low as I would want to use.

The reason that I place a 50% limit is because as a battery ages the mAh of the battery degrades, as the mAh degrades so does the batteries c rating (amp limit). So down the road, a 30A battery may only be a 15A battery.
 

Spencer87

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well answer a few more clarification questions.
what battery are you using?
And do you want to
A) almost definitely blow your face off (0.1-------0.000001 ohm)
B) Probably blow your face off (0.16 ------0.1
C) maybe Blow your face off (0.27-0.16)
D) Probably not blow your face off unless there is some freakish accident (0.30-0.27)
E) Almost definitely not blow your face off (5.0- 0.30)

this is all providing you have a battery that isnt ~fire or Fire~
And that your battery is a safe battery used for vaping.
and you charge correctly.
and you dont light fireworks off pointing them at your face.


Anyways.. Kinda Joking a bit... In all seriousness... It really depends.

read a bunch of these

(18) Baditude's Blogs | E-Cigarette Forum

preferably start with number 9-17

then make an informed decision.
 
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Susan~S

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Mooch

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    to be save at lower ohms have a look at LiFePo4.
    I have good expiriences with A123 ANR26650M1B.
    A truly amazing cell. Safest of all the lithium chemistries, but lower voltage. Not so good for use in a regulated mod because of this. Great for mechs though because you can just adjust the coil resistance to match the lower, 3.3V, nominal voltage.
     

    Mooch

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    I'm using Sony VTC4's right now, with intentions of going up to the VTC5's soon.
    The Sony's are supposedly rated for 60 amp pulse, 30 amp continuous. I vape at .16ohms no problem, though the mod gets pretty warm during chain/liquid sampling sessions, so I wouldn't go much lower than that.

    I say stay with the VTC4's. :)
    The VTC5's are a 20A battery and would be a step down from the VTC4's. The capacity above 20A is about the same and the VTC4 runs cooler at these very high current levels.

    Sony VTC5 20A 2600mAh Bench Test Results...a good 20A cell | E-Cigarette Forum

    The HB6 is the only true 30A battery I know of, with the VTC4 and HD2 a close second. See my signature for a list of the battery tests I've done.
     
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    Trypno

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    I say stay with the VTC4's. :)
    The VTC5's are a 20A battery and would be a step down from the VTC4's. The capacity above 20A is about the same and the VTC4 runs cooler at these very high current levels.

    Sony VTC5 20A 2600mAh Bench Test Results...a good 20A cell | E-Cigarette Forum

    The HB6 is the only true 30A battery I know of, with the VTC4 and HD2 a close second. See my signature for a list of the battery tests I've done.

    RTD Vapor has the VTC5's listed at 30amps...so what's the real rating? I thought the VTC5's were the same as the VTC4's, but with higher mAh?
     

    Mooch

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    RTD Vapor has the VTC5's listed at 30amps...so what's the real rating? I thought the VTC5's were the same as the VTC4's, but with higher mAh?

    The real rating is 20A.
    It never was a 30A cell. There was supposed to have been a 30A discharge graph in an earlier version of the technical document ("datasheet") that was going around but it was removed at least two years ago. It was not a graph that showed the cell's rating, just what happens to the cell if you discharge it at 30A. Misinterpretation of this graph could be part of the problem.

    There is no discharge graph or spec in the Sony documentation that goes above 20A. In fact, the cycle life spec for the VTC5 is at 10A! The 20A rating we give it is an abusive absolute max continuous rating. And tests show a significant loss in voltage and capacity above 25A and a dangerously high temperature at 25A. It really is just a 20A cell.

    Why do vendors keep saying it's a 30A cell? You'll have to ask them to know for sure. One reason could be that they just don't know the real rating and repeat what they've heard. Another reason is that having another 20A cell on the market doesn't stand out and sell well. However, saying it's a 30A cell will get a lot more people to buy it.

    Another way to look at things, when comparing the VTC4 and VTC5, is that capacity and current rating are essentially opposites. If one goes up, the other typically has to go down. You can't increase both much without increasing the size of the cell or making it very expensive. So when they took the VTC4 and increased its capacity, they had to lower the current rating....leading to the VTC5.
     

    Mooch

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    Ok seriously @Mooch i have been meaning to ask this for some time now. What is it you do for a living?

    Im guessing pure sciences...more likely chem than physics based on battery knowledge.

    Since 1992 I've been an electrical engineer specializing in power management...power supplies, battery chargers, battery management and protection systems, electronic loads (for testing batteries and power supplies), energy harvesting (getting power from solar, thermal, and vibration), energy storage (batteries and ultracapacitors), and similar products.

    I loved physics in school though, still do. Mostly leaning towards particle physics and cosmology. Two vastly different realms but a surprising amount of crossover. My battery knowledge has been self taught over the years. From both the testing and evaluation of batteries for clients and what I can absorb from trade journals, research papers, datasheets, new product announcements, etc.
     

    Mooch

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    Electrical engineer makes sense!

    Im currently in the process of hanging up the chef jacket i wore for 20+ yrs to go back to school for a degree in physics and minor in chem. Then...who knows?

    Chef...that's awesome! A secret life desire of mine.
    Congratulation on taking such a big step! I hope it leads to something incredibly cool. :)
     

    Darth Omerta

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    Thanks!

    My thought is that a degree in physics amd minir in chem IS something incredibly cool!
    :2cool:

    Cheffing has been fun and its helping me in the DIY juice dept but i like science more.

    The original goal was to persue astrophysics but i recently got bitten by the particle physics bug myself. Just gonna go for my degree and see where that takes me!
     
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