Hated Physics growing up - and now all this - looks like I am doomed......
How is sub-ohm vaping dangerous?
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don't be intimidated by the math - there are guides, calculators, and help available everywhere. it's the same as anything else, if you want to get good at it while still being safe, it takes some work and some practice. after a short while, everything will become almost second nature.
the problems tend to occur when you try to take shortcuts - people who do that are the ones who give sub-ohmers a bad name, and are the reason why a lot of people on the forum shun and/or ridicule us.
the problems tend to occur when you try to take shortcuts - people who do that are the ones who give sub-ohmers a bad name, and are the reason why a lot of people on the forum shun and/or ridicule us.
Ok I surrender!!!!!!!!!! I've spent several hours trying to find the manufacturers specs on a few batteries. This thread has me curious about the C ratings of the batteries I'm using.
Name brands are AW IMR , Efest IMR, also the AW ICR protected and the Efest protected. (I won't even worry about the ICR Panasonics. They only get used in the Evic. But if someone could clue this old man in I would appreciate it.).
I can find a lot of info for batteries that are for RC cars and such as that, but not the specific brands I'm using.
Name brands are AW IMR , Efest IMR, also the AW ICR protected and the Efest protected. (I won't even worry about the ICR Panasonics. They only get used in the Evic. But if someone could clue this old man in I would appreciate it.).
I can find a lot of info for batteries that are for RC cars and such as that, but not the specific brands I'm using.
If I do a search like: "AW IMR 18650 1600mAh specifications"
I get stuff like this . . . https://www.google.com/url?sa=t&rct...=WL_zjXeUzKlVVDsMOsDhHQ&bvm=bv.51495398,d.cGE
. . . wherein I see a C-rating of 15C. 15X1.6=24amps
the AW 2000mAh is 10A
efest 2000 is listed differently; but I see it says "Acceptable performance up to 7A, but they have problems with 10A."
I don't buy batteries for which I cannot find specs, hard numbers, in plain language that I understand. Even then, I take those numbers with a zoiDman-type grain of salt.
I get stuff like this . . . https://www.google.com/url?sa=t&rct...=WL_zjXeUzKlVVDsMOsDhHQ&bvm=bv.51495398,d.cGE
. . . wherein I see a C-rating of 15C. 15X1.6=24amps
the AW 2000mAh is 10A
efest 2000 is listed differently; but I see it says "Acceptable performance up to 7A, but they have problems with 10A."
I don't buy batteries for which I cannot find specs, hard numbers, in plain language that I understand. Even then, I take those numbers with a zoiDman-type grain of salt.
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I'm not sure if this is the eFest web site or not. But for this Battery they say it has a Max Discharge Rate of 10A
Efest IMR 18650 2250mAh 3.7V High Drain Li-Mn Battery with Button top (1pc)
Efest IMR 18650 2250mAh 3.7V High Drain Li-Mn Battery with Button top (1pc)
If I may hopefully add to the understanding of irrational vaping - "Sub Ohming". I believe that a graphic representation of Ohm's Law assuming a freshly charged battery at 4.1 v and an ever decreasing resistance.
Don't know how someone can vape at 0.1 ohms
Don't know how someone can vape at 0.1 ohms
If I may hopefully add to the understanding of irrational vaping - "Sub Ohming". I believe that a graphic representation of Ohm's Law assuming a freshly charged battery at 4.1 v and an ever decreasing resistance.
Don't know how someone can vape at 0.1 ohms
What's the Scale on the Horizontal Axis of your Graph?
If I may hopefully add to the understanding of irrational vaping - "Sub Ohming". I believe that a graphic representation of Ohm's Law assuming a freshly charged battery at 4.1 v and an ever decreasing resistance.
Don't know how someone can vape at 0.1 ohms
irrational vaping? how about irrational graphs? here, i fixed it for you:
Well, now, there's a coupla' things I like about these batteries:
#1 no name
#2 no specifications or discharge ratings
#3 no search for such . . . because . .. that's right NO NAME
#4 the two sites which I checked sold some real SH_T batteries right alongside them
#5 $2.95 (seriously? Yeah, I'd trust my face to $2.95)
Oh, I did find one reference (at ljesmokes) that said "Not recommended for use with atomizers or cartomizers below 2.0 ohm resistance."
Aren't those Four 1.2 volt cells in Series?
http://www.efestbattery.com/index.php?route=product/product&path=57_69&product_id=106
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Its resistance; it should show as 4.1 down to .1 but obviously does not.
I know this thread has been beaten to death by most on the dangers of sub-ohm vaping. However, I wanted to chime in with an engineer's perspective as to the 'why' it is dangerous to push batteries beyond their capabilities.
The trouble with pulling huge amounts of current through a non-safe chemistry battery (read: every battery you use in a mod) is not necessarily current, but heat. The truth is, Lithium is a highly reactive element, and despite the chemistry of modern batteries we still have to worry about the substrate of batteries deteriorating under heat, and the lithium reacting with its surroundings.
Any battery in the real world has an (usually small) internal resistance. For practical purposes, it's safe to assume that this value is below 0.1 ohms. But if you do the math on a sub-ohm setup, you see where the problem is. Let's take, for example, this great post by djslik:http://www.e-cigarette-forum.com/fo...ms/462202-how-sub-ohm-vaping-dangerous-3.html
In his example, with a .3 ohm coil, and .05 ohms in both the mod and the battery, he comes up with 10.5 amps in the circuit. If you do the power calcs (P = I^2*R), you find that with that circuit you're putting out roughly 33 W through the atty. However, we also have to consider that you're putting out power INTO THE INTERNAL RESISTANCE OF THE BATTERY. Using djslik's numbers, this power into the battery (as heat) is roughly 5.5 W. Compare this with what someone would call a 'more safe' setup, running only 3A through a 1.3 ohm coil, and the heat into the battery is only .45 W.
So what does that mean? Power, literally, is the rate at which energy is transferred into or out of a system. So, referring to the above examples, with a .3 ohm coil and some assumed numbers on battery resistance, the 'unsafe' setup is pumping heat into the battery at a rate greater than 10 times that of the 'more safe' setup. Food for thought.
Now, the point, which I eluded to earlier. Heat is the killer of batteries. The hotter the battery, the greater the chance there is for the underlying chemistry of lithium batteries to go unstable, and into a condition known as 'thermal runaway.' Basically, the heat allows a chemical reaction inside the batteries, which generates more heat, which causes more reactions, etc etc etc. This is what happened to the 787's which were grounded for battery fires a few months ago, using a battery chemistry which is VERY similar to that which you use on a daily basis to heat up your favorite nic juice.
Reputable battery manufacturers publish specifications for maximum charge and discharge rates of their batteries, along with numerous other data, so that designers can properly utilize their product. The manufacturer more or less guarantees that its batteries will perform safely, as long as they are kept within spec. It is the job of the designer (in this case, the modder) to make sure he stays within those limits.
Whew! Okay, end rant. Hope that sheds a little light on the subject for everyone.
The trouble with pulling huge amounts of current through a non-safe chemistry battery (read: every battery you use in a mod) is not necessarily current, but heat. The truth is, Lithium is a highly reactive element, and despite the chemistry of modern batteries we still have to worry about the substrate of batteries deteriorating under heat, and the lithium reacting with its surroundings.
Any battery in the real world has an (usually small) internal resistance. For practical purposes, it's safe to assume that this value is below 0.1 ohms. But if you do the math on a sub-ohm setup, you see where the problem is. Let's take, for example, this great post by djslik:http://www.e-cigarette-forum.com/fo...ms/462202-how-sub-ohm-vaping-dangerous-3.html
In his example, with a .3 ohm coil, and .05 ohms in both the mod and the battery, he comes up with 10.5 amps in the circuit. If you do the power calcs (P = I^2*R), you find that with that circuit you're putting out roughly 33 W through the atty. However, we also have to consider that you're putting out power INTO THE INTERNAL RESISTANCE OF THE BATTERY. Using djslik's numbers, this power into the battery (as heat) is roughly 5.5 W. Compare this with what someone would call a 'more safe' setup, running only 3A through a 1.3 ohm coil, and the heat into the battery is only .45 W.
So what does that mean? Power, literally, is the rate at which energy is transferred into or out of a system. So, referring to the above examples, with a .3 ohm coil and some assumed numbers on battery resistance, the 'unsafe' setup is pumping heat into the battery at a rate greater than 10 times that of the 'more safe' setup. Food for thought.
Now, the point, which I eluded to earlier. Heat is the killer of batteries. The hotter the battery, the greater the chance there is for the underlying chemistry of lithium batteries to go unstable, and into a condition known as 'thermal runaway.' Basically, the heat allows a chemical reaction inside the batteries, which generates more heat, which causes more reactions, etc etc etc. This is what happened to the 787's which were grounded for battery fires a few months ago, using a battery chemistry which is VERY similar to that which you use on a daily basis to heat up your favorite nic juice.
Reputable battery manufacturers publish specifications for maximum charge and discharge rates of their batteries, along with numerous other data, so that designers can properly utilize their product. The manufacturer more or less guarantees that its batteries will perform safely, as long as they are kept within spec. It is the job of the designer (in this case, the modder) to make sure he stays within those limits.
Whew! Okay, end rant. Hope that sheds a little light on the subject for everyone.
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