Jalcide

I wonder what the penalty / fines are for updating software and firmware, if it's indeed illegal. It's either not worth the risk, from a business perspective, or the cost of doing business if it's not too much and doesn't incur further negative status or action. At some point, the answers to these simple questions will fit in a 140 character tweet.

Yup. It's very worrisome. I will say that August 8th is not here yet, and 5 days can make all the diference in software development. So perhaps we'll see an Aug 8 (or Aug 7) release. If indeed this is the correct interpretation of the regulations.

I was wondering this, too. :/ If indeed there will be a freeze on software / firmware updates on Aug 8th, I hope we'll see a new version posted in time, that includes the smoothing algos. Even if it's beta, it would be hugely welcomed.

I guess it's all moot now. I just ran the math. I was wrong in a key assumption. The rise and fall of twice the ohms in the parallel circuit does happen, like I suspected, but the math of the TCR formula, when paired with parallel resistor math, works out to keep the temperature the same in each coil, between dual and single. Here's the math for a .15-ohm Ni200 build, with a .1 ohm rise and drop in resistance: TCR formula: (Rref + rD) = Rref [1 + a(T - Tref)] R = resistance at temp TRref = resistance at temp Trefa = TCRT = tempTref = ref temp for the TCRrD = resistance delta (rise) Single coil build TCR formula: (.15 + .1) = .15[1 + .006(T - 20)] A .1-ohm rise and fall equates to 131.1C, or 267.9F. For the dual build to read at .15-ohm, each coil needs to be .3-ohm. So the same .1-ohm rise of the circuit, means each resistor inside it must rise .2 ohm. Dual coil build TCR formula: (.3 + .2) = .3[1 + .006(T - 20)] A .2-ohm rise and fall required for each coil equates to 131.1C, or 267.9F I still don't fully have my head wrapped around why this is true. But I'm going to accept the math, for now.

Okay, if you're going to assume increased airflow (harder draw), that's going to increase cooling as it relates to the extra heat production. Probably a smart idea, too. Although temp control will help lower vapor production when not drawing as much air. Anyway, this seems pretty linear and in balance with the larger build. More vapor, more airflow taking that extra vapor away. In other words, the extra airflow balances the extra product of the build. We're still not accouting for the drastic increased cooling we're seeing with dual TC builds (on mods without a mystery "dual coil" TC setting -- which I suspect accounts for what I'm suggesting). So, I don't think any of this overshadows the mechanism of: 1 ohm of reported cooling, equaling 2 ohms of actual cooling time. Because that's happening at the sampling rate. It's got to be a huge factor, when averaged over time. In keeping with the shift in linear graphs that some others have posted, that happen with dual TC builds. The accuracy of said graphs is somewhat in question, however -- which is why I'm trying to confirm or debunk it with smart people like you (thank you, btw, for entertaining me on this, on Xmas Eve no less! I owe you a beer or three.) As for doubling the heat transfer with doubled surface area -- sure, but the system also has double the power pushed to it to get to that state. In a parallel config, the volts stay the same across the coils, so it would be amperage that does the deed. In other words, that extra heat transfer is not adding to the cooling effect, it's just keeping what's being thrown at it, in check.

Well, strictly-speaking, all of the watts go toward heating the wire. The electrons flow nowhere else. It's a subtle point to make, but helps to frame what the the vapor production really is: part of the cooling process (evaporation) of surplus heat that was there to get rid of. The vapor isn't providing additional cooling. There can be more heat than vapor (dry hit), but not more vapor than heat. The wicking makes sure there's not more liquid in either system, for a given segment of coil. Sorry, I digressed, back to the main points...Yes, I agree we're carrying away more net heat, for the larger amount of power we're putting into the larger mass of the system. But let's pick a small, arbitrary segment of the coil (and the wicking material it touches) for a thought experiment. Let's say a single wrap of a spaced coil (of any length). I suspect each wrap-segment, when viewed under close, isolated inspection is not behaving much differently during the cooling cycle. The only "connection" it has to the thermodynamic system around it that represents the "2x part" is through heat conduction across the 2x length of wire. The other methods of heat transfer, evaporation, convection and radiation are the same in both systems; same amount of wicking material and liquid in direct contact with any given wrap-segment of coil, same amount of airflow through the atomizer (actually, slightly less, but we can ignore that). The only contribution toward cooling we see is the longer length of wire. And I don't think it helps much, certainly not twice as much. It would help slightly more, the larger the wire gauge. In fact, the additional heat generated inside the atomizer for a dual build is working to slow the cooling, but this is probably a lesser effect than my supposition; 1 ohm of cooling as the mod calculates it, taking 2 ohms of cooling of actual time = temp is always cooler than mod calculates. This is only during the cooling cycle. The mod then blasts power at it again to compensate. So it's the net effect of that battle. But where the mod is slow to reapply power, it's quick to cut the power when the TCR delta is reached.

Yeah, I was thinking along the same lines, the 2x mass thing. But I'm now thinking it's all about how that mass is distributed. I'm guessing there's not twice the cooling with a coil twice the length, for the same reason a 3 inch wire and 6 inch wire would both glow about the same when heating an end (or any part of it) with a blowtorch; the heat dissipation across a wire is not so good. We see this heat gradient at the hotspot, but it drops off pretty quickly. I think there is an effect of the longer coil dissipating more heat, just not 2x. At the same time, the ohms (and temperature) is about twice in each resistor, because of how linear most TCRs are. So we have twice the heat, but not twice the cooling.

Thanks for the continued discussion, guys. I'm still thinking there are raw physics that play into why a dual coil build is often anemic, when driven by a TCR based control system. I think I figured it out! If not, then this is at least some brilliant folly. Coils in parallel, being resistors, will still be seen by an ohm meter (the mod) as a single resistor. To keep the math simple, let's assume they are perfectly identical, 1-ohm coils. Two 1-ohm coils in parallel create the equivalent of a .5-ohm resistor. Let's assume they heat and cool mathematically perfect, in perfect unison, and therefore this "variable" resistor (controlled by its temperature) is easier to discuss. We now have "one" resistor for the mod to analyze hundreds of times a second, as it does. It's looking for a change in resistance. That change has to be expressed in milliohms, or some such finite unit of granularity. It's looking for so many units of change per unit of time. A Heating Cycle: Each increased milliohm that a single, serial wire would report back, is now taking twice the milliohms (for each coil independently) for the circuit as a whole to report back as 1 milliohm of change. Not a problem for the mod, it will happily push more wattage at it until the heat increases enough in both coils to increase the ohms enough to meet the TCR's delta enough to decide it's reached the target temperature. A Cooling Cycle: I think this is where the "magic" happens (the magic of dual coils being anemic). The power is cut (or reduced) and waiting for the milliohms to drop sufficiently so that it can kick in again. But just as before, it takes 2 milliohms of change in each coil, to produce 1 milliohm of change for the circuit as a whole. Since the cooling is a "static" function of the thermodynamics of the coil mass and surface area (and wick), it doesn't have the benefit of a mod to push more cooling at it. It just has to cool at its own natural rate. The cooling that happens on each coil, independently, is identical in behavior to its single coil counterpart; even when each coil, of a dual, has more wraps, they don't work to retain the heat more, due to the topology of a spiral, spaced coil. So the cooling cycle is nearly identical between the single build and dual build, but the dual build is required to cool longer, a full 2 milliohms drop in resistance worth of cooling, longer, to report back only 1 milliohm worth of cooling as the mod sees it. I believe it's this extended cooling cycle, repeated over and over (perhaps dozens or even hundreds of times a second) that results in a net cooler temperature, as compared to the ohm-unhampered single coil build. The single coil, reports "I'm cooler now," faster. The dual coil reports "I'm cooler now," slower and therefore, in fact is cooler than the single coil would be, at that reporting.

I greatly appreciate your thoughts, David. Thanks, I just may add these good points to the conversation. (Feel free to add more, if you think of anything. And I could append them over on what is already turning out to be lively discussion.)

Thanks, Jaquith. Feel free to cut and paste your thoughts over on the ECF thread, if you're so inclined. I'm hoping to get the "TCR is different" originator's response to all this, as well. He was so very confident, and a seasoned ECF member, I'm quite interested in his rebuttal. My current thinking is focused around heat dissipation as a possible culprit to why the dual coil TC builds are anemic, all other things being equal.

Thanks much, as always, Jaquith. Yes, let's assume they are mathematically perfect. There has been some assertions that the TCR effectively "changes" when viewed as a parallel circuit. It has some pretty convincing charts and equations tossed in as supporting "evidence." I bought it hook line and sinker, and thought the reason had to do with Heat Flux differences in a dual build (per Steam Engine). The discussions that ensued, on two ECF threads, no less, have all but detailed them. I've now started a new thread to get this confirmed or debunked once and for all -- by those with enough of a grasp of the physics behind it, to put it to rest. https://www.e-cigarette-forum.com/forum/threads/do-dual-coils-affect-tc-accuracy.721108/ The graph that is shown to support the idea of the TCR being different in dual configs, is of particular interest (see the first post of the thread if you're interested). It is real? Summary version: A parallel circuit will increase about 1/2 TCR per degree C. A single coil nets about 0.438 ohm delta from 0 to 300C. A dual coil nets about 0.234 ohm delta from 0 to 300C. He seems to imply the actual TCR effectively becomes "different" when viewed as a parallel circuit by the mod.

It's been asserted that the parallel circuit of a dual coil will effectively change the TCR, from the mod's point of view. Is there any merit to this? I'm looking for the science behind the often anemic dual coil TC experience.

Interesting. I thought the Ohm Lock Range was only the threshold (max percentage difference) for when the "new coil / same coil" prompt displays. I didn't think it controlled anything regarding Refinement. Or, are we saying that when it's set higher, it will allow the ohms to drift without the prompt? I guess that would make sense.

The only real info I've seen seems to suggest that not much of any of these alloys is ending up in the vape. https://www.youtube.com/watch?v=Cvb4Wzf_xyk The toxic Nickel compounds people talk about, don't occur at these temps or oxygenated conditions. Titanium Dioxide -- "nano" versions of it -- the main worry -- also are not created under vape conditions. I don't know the real answers and I don't think anyone does, but I suspect the safety looks something like this (my guesses from safest to least safe): Titanium (because it's so very inert and is used in medical implants). Stainless Steel (because it's so non-reactive and also used in medicine, food prep and cooking) Nickel (because it's run via temp control and is keeping the overall vape safer) These are just my feelings. Vape at your own risk. It's certainly not risk free. But I worry about what's created from VG, PG and flavorings way more than the wire.

Howdy. Sure, so... Some wire predictably changes resistance as its temperature increases (and decreases). It's this changing resistance, that's measured many times a second, that allows the chip to throttle the energy hitting the coil so that it can match a desired temperature. Wire that has a large change in its resistance as its temperature changes -- a higher TCR (Temperature Coefficient of Resistance) -- is good wire for this job. The base resistance of the wire also matters (the higher the value the more accurate TC precision is), but let's ignore that right now to keep it simple. The complexity of the math that describes the change (linear, curved, s-curved, etc.) also factors in, but we'll ignore this, too. Kanthal has a very low TCR; its resistance doesn't change much as it gets hotter or cooler. This is why it's a poor TC wire. Not only would the chip need to be extraordinarily sensitive to detect the changes, but the rest of the electrical connections in the mod and atomizer would need to be in a near laboratory setting; gold plated connection, etc. So, kanthal is at the bottom of the TC precision list. Nickel has a very high TCR, but also very low base resistance, so it's a great TC wire, but actually not the best theoretical wire for TC. Titanium is in the sweet spot of having a high TCR and also fairly high base resistance and some consider it the best for TC. I think the best wire, in theory, is 430 SS, once you factor in the base resistance and TCR. It ends up having the highest TC precision value. In practice, I don't know if this works out to be true. I have some 430 on order, but haven't been hands on with it yet. My feeling right now is that Titanium probably is the most accurate TC wire, followed by Nickel, followed by SS.