TC beyond Ni200: Nickel Purity, Dicodes; Ti, SS, Resistherm NiFe30; Coefficient of Resistance
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@vapealone ! I was just thinking it would be awesome if we could compare all the wires we've discussed from a point of view of accuracy.
What do you think about extending your spreadsheet to show, for each wire, the Accuracy Factor, AKA "Accurate to nearest X°C on a mΩ-accurate mod" ?
It would be the following calculations:
for every wire, ideally with a resulting graph comparing them all - a vertical bar graph I guess?
Two points of doubt:
What do you think?
What do you think about extending your spreadsheet to show, for each wire, the Accuracy Factor, AKA "Accurate to nearest X°C on a mΩ-accurate mod" ?
It would be the following calculations:
for every wire, ideally with a resulting graph comparing them all - a vertical bar graph I guess?
Two points of doubt:
- What base resistance to choose?
- Above I used an example coil at a typical size/gauge - which just happened to be the coil size I most often build myself
- That works OK?
- Or do you have a cleverer way, based on the Resistivity number, eg 0.20 for NiFe70?
- Above I used an example coil at a typical size/gauge - which just happened to be the coil size I most often build myself
- What TCR to choose for non-linear wires?
- I suppose the only way is to do the comparison based on a single "vaping Range TCR" for each wire
- ie around 0.006 for Ni200, 0.0035 for Titanium, or whatever your averaged figure comes out to up to, say, 250°C?
What do you think?
To add: the above calculation is only intended to be a rough guide, a quick snapshot figure to compare different wires and to give a ballpark accuracy figure for a given wire.
It varies with base resistance, hence the difficulty of choosing a single "example coil".
But I would say the majority of people build in a fairly similar way, and 8 wraps x 3mm is probably a good average. Or maybe 2.5mm, whatever the consensus is.
In any case, for the Wire X vs Wire Y comparison it doesn't matter if a given person builds very differently to that, as long as they would build the same coils with Wire X as they would with Wire Y. Then at least the ratio is the same.
And probably much more interesting than comparing wire X to wire Y on accuracy (because most of them are going to be accurate enough), it will enable us to say: "Ah, you're vaping Titanium - assuming you build to around 0.4Ω you're going to be accurate to roughly the nearest X°C on a mΩ mod and roughly 10X°C on a 10-mΩ mod" which helps people understand how accurate their TC will be on a given mod, which might also then tell them something about the effect of static resistance on that wire on that mod*.
We can also then easily caveat such statements with "if you build to double that resistance it'll be twice as accurate as that." And so on.
* Though re static resistance, this is something I still need to investigate. Dicodes in their App Guide, did a simple multiplying - they said that as Ni200 at 0.1Ω is accurate to nearest 1.6°C - ie it rises in temp by 1.6°C per milli-ohm - then with 10mΩ of static resistance, the inaccuracy is 16°C. But I'm not sure if that's right.
Because although yes it does change the base resistance by 10mΩ, it will also usually change the final resistance by 10mΩ - because I think we can usually assume that the static resistance in the atomizer really is static - it doesn't get heated up nearly as much as the coil, if at all, and therefore it is simply added, unchanged, to the final resistance value. (And even if it was heated, it's of a completely different material - brass, SS, maybe copper - and so the TCR would be quite different.)
On that basis, when I add static resistance both to the base resistance and to the final resistance, I find that TCR is completely irrelevant, only base resistance matters. And therefore static resistance has precisely the same effect on Ni200 as it does on SS as it does on Titanium and all the rest.
But I need to think and test that a bit more, given Dicodes says differently. Not that I trust Dicodes implicitly any more; far from it
It varies with base resistance, hence the difficulty of choosing a single "example coil".
But I would say the majority of people build in a fairly similar way, and 8 wraps x 3mm is probably a good average. Or maybe 2.5mm, whatever the consensus is.
In any case, for the Wire X vs Wire Y comparison it doesn't matter if a given person builds very differently to that, as long as they would build the same coils with Wire X as they would with Wire Y. Then at least the ratio is the same.
And probably much more interesting than comparing wire X to wire Y on accuracy (because most of them are going to be accurate enough), it will enable us to say: "Ah, you're vaping Titanium - assuming you build to around 0.4Ω you're going to be accurate to roughly the nearest X°C on a mΩ mod and roughly 10X°C on a 10-mΩ mod" which helps people understand how accurate their TC will be on a given mod, which might also then tell them something about the effect of static resistance on that wire on that mod*.
We can also then easily caveat such statements with "if you build to double that resistance it'll be twice as accurate as that." And so on.
* Though re static resistance, this is something I still need to investigate. Dicodes in their App Guide, did a simple multiplying - they said that as Ni200 at 0.1Ω is accurate to nearest 1.6°C - ie it rises in temp by 1.6°C per milli-ohm - then with 10mΩ of static resistance, the inaccuracy is 16°C. But I'm not sure if that's right.
Because although yes it does change the base resistance by 10mΩ, it will also usually change the final resistance by 10mΩ - because I think we can usually assume that the static resistance in the atomizer really is static - it doesn't get heated up nearly as much as the coil, if at all, and therefore it is simply added, unchanged, to the final resistance value. (And even if it was heated, it's of a completely different material - brass, SS, maybe copper - and so the TCR would be quite different.)
On that basis, when I add static resistance both to the base resistance and to the final resistance, I find that TCR is completely irrelevant, only base resistance matters. And therefore static resistance has precisely the same effect on Ni200 as it does on SS as it does on Titanium and all the rest.
But I need to think and test that a bit more, given Dicodes says differently. Not that I trust Dicodes implicitly any more; far from it
To add: the above calculation is only intended to be a rough guide, a quick snapshot figure to compare different wires and to give a ballpark accuracy figure for a given wire.
It varies with base resistance, hence the difficulty of choosing a single "example coil".
But I would say the majority of people build in a fairly similar way, and 8 wraps x 3mm is probably a good average. Or maybe 2.5mm, whatever the consensus is.
In any case, for the Wire X vs Wire Y comparison it doesn't matter if a given person builds very differently to that, as long as they would build the same coils with Wire X as they would with Wire Y. Then at least the ratio is the same.
And probably much more interesting than comparing wire X to wire Y on accuracy (because most of them are going to be accurate enough), it will enable us to say: "Ah, you're vaping Titanium - assuming you build to around 0.4Ω you're going to be accurate to roughly the nearest X°C on a mΩ mod and roughly 10X°C on a 10-mΩ mod" which helps people understand how accurate their TC will be on a given mod, which might also then tell them something about the effect of static resistance on that wire on that mod*.
We can also then easily caveat such statements with "if you build to double that resistance it'll be twice as accurate as that." And so on.
* Though re static resistance, this is something I still need to investigate. Dicodes in their App Guide, did a simple multiplying - they said that as Ni200 at 0.1Ω is accurate to nearest 1.6°C - ie it rises in temp by 1.6°C per milli-ohm - then with 10mΩ of static resistance, the inaccuracy is 16°C. But I'm not sure if that's right.
Because although yes it does change the base resistance by 10mΩ, it will also usually change the final resistance by 10mΩ - because I think we can usually assume that the static resistance in the atomizer really is static - it doesn't get heated up nearly as much as the coil, if at all, and therefore it is simply added, unchanged, to the final resistance value. (And even if it was heated, it's of a completely different material - brass, SS, maybe copper - and so the TCR would be quite different.)
On that basis, when I add static resistance both to the base resistance and to the final resistance, I find that TCR is completely irrelevant, only base resistance matters. And therefore static resistance has precisely the same effect on Ni200 as it does on SS as it does on Titanium and all the rest.
But I need to think and test that a bit more, given Dicodes says differently. Not that I trust Dicodes implicitly any more; far from it
Took me a bit of noodling to see it, but you are spot on; static resistance is irrelevant when comparing wire accuracy. Same static resistance has same effect on TC accuracy.
Hmm.@vapealone ! I was just thinking it would be awesome if we could compare all the wires we've discussed from a point of view of accuracy.
What do you think about extending your spreadsheet to show, for each wire, the Accuracy Factor, AKA "Accurate to nearest X°C on a mΩ-accurate mod" ?
It would be the following calculations:
for every wire, ideally with a resulting graph comparing them all - a vertical bar graph I guess?
Two points of doubt:
- What base resistance to choose?
- Above I used an example coil at a typical size/gauge - which just happened to be the coil size I most often build myself
- That works OK?
- Or do you have a cleverer way, based on the Resistivity number, eg 0.20 for NiFe70?
- What TCR to choose for non-linear wires?
- I suppose the only way is to do the comparison based on a single "Vaping Range TCR" for each wire
- ie around 0.006 for Ni200, 0.0035 for Titanium, or whatever your averaged figure comes out to up to, say, 250°C?
What do you think?
You got me here
My humble suggestion is to use some normalised indicator.
For demonstration purpose only I have added a Beta version to the spreadsheet
This beta version shows the different materials temperature sensitivity compare to Ni200's sensitivity at 100°C when both the given material and Ni are the same size (length, DIA etc).
It doesn't need actual size or ohm to enter but doesn't shows actual accuracy either.
That is why I called it Indicator
However, it is pretty good to compare materials. Seems Ti is the ultimate winner, NiFe52 solid second then a desperate knife fight for the last place on the podium followed by S/S and Ni200/Ni DH on the rock bottom
Good enough or I need to do better than this?
P.S.:
@TheBloke, FYI it is not on the first tab but on the 5th cryptically named as 'Sensitivity Indicator (Beta) (20°C-T)'. Besides, some scrolling my be needed too....
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Thank you! I like it! Any chart that shows Ni200 as the b*tch gets my vote
Of course I should have guessed that you'd turn my crude specific request into something general and beautiful
I am amazed though - I had no idea Ni200 would be worst. I mean I knew it was the worst material in practice, but had never imagined it would also be worst in terms of sensitivity and therefore theoretical accuracy.
I thought its super low resistance was going to be balanced out by the high TCR, higher than most of the others. Though I suppose I keep forgetting that its TCR is averaged across the range is not the 0.006 I keep associating it with, and that at 200°C it's only 0.005. Kanthal DH looks like I always think of Ni200 looking.
I don't understand why Dicodes listed Ni200 as 0.0062 - though the last few days has seen me completely disillusioned with many of Dicodes' estimations, so I suppose that should be no surprise. It's quite possible they just copied it off a datasheet which was quoting it across a wider range.
Though they then showed it on a graph of 0-300°C, clearly showing it 62%/100°C in that range. I don't get that at all. Have they been so dumb as to take a general figure off the interwebs, assume it applied to the vaping range when it didn't, then put it on a graph and use it for all their textual descriptions of Ni200's accuracy? I suppose they must have. On that same graph they also said "the change is a curve but we can ignore that here", when we most certainly can't, or at least shouldn't, ignore it for Ni200 if we're going to show a graph from 0-300°C. I had such high hopes, Dicodes, and you have dashed them!
Anyway, awesome work, thank you!
I must admit I'd still love to see 'real life' figures of accuracy to nearest X°C for a specified coil. So we can gauge the real life effect we're talking about, in terms easily understood.
I do realise such crude specificity, relying on an assumption of base coil and probably a single TCR figure, sticks in the eye for beauty of the mathematician. But for Neanderthals such as myself its comforting
But I can do that myself, as part of an overall wire comparison chart. You're right it doesn't fit on your generalised charts.
Cheeky bugger
Of course I should have guessed that you'd turn my crude specific request into something general and beautiful
I am amazed though - I had no idea Ni200 would be worst. I mean I knew it was the worst material in practice, but had never imagined it would also be worst in terms of sensitivity and therefore theoretical accuracy.
I thought its super low resistance was going to be balanced out by the high TCR, higher than most of the others. Though I suppose I keep forgetting that its TCR is averaged across the range is not the 0.006 I keep associating it with, and that at 200°C it's only 0.005. Kanthal DH looks like I always think of Ni200 looking.
I don't understand why Dicodes listed Ni200 as 0.0062 - though the last few days has seen me completely disillusioned with many of Dicodes' estimations, so I suppose that should be no surprise. It's quite possible they just copied it off a datasheet which was quoting it across a wider range.
Though they then showed it on a graph of 0-300°C, clearly showing it 62%/100°C in that range. I don't get that at all. Have they been so dumb as to take a general figure off the interwebs, assume it applied to the vaping range when it didn't, then put it on a graph and use it for all their textual descriptions of Ni200's accuracy? I suppose they must have. On that same graph they also said "the change is a curve but we can ignore that here", when we most certainly can't, or at least shouldn't, ignore it for Ni200 if we're going to show a graph from 0-300°C. I had such high hopes, Dicodes, and you have dashed them!
Anyway, awesome work, thank you!
I must admit I'd still love to see 'real life' figures of accuracy to nearest X°C for a specified coil. So we can gauge the real life effect we're talking about, in terms easily understood.
I do realise such crude specificity, relying on an assumption of base coil and probably a single TCR figure, sticks in the eye for beauty of the mathematician. But for Neanderthals such as myself its comforting
But I can do that myself, as part of an overall wire comparison chart. You're right it doesn't fit on your generalised charts.
@TheBloke, FYI it is not on the first tab but on the 5th cryptically named as 'Sensitivity Indicator (Beta) (20°C-T)'. Besides, some scrolling my be needed too....
Cheeky bugger
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(...)
Of course I should have guessed that you'd turn my crude specific request into something general and beautiful
I am amazed though - I had no idea Ni200 would be worst. I mean I knew it was the worst material in practice, but had never imagined it would also be worst in terms of sensitivity and therefore theoretical accuracy(...)
I was surprised too. And may need to double-check the formulas
But I have to agree that Ni is a sort of dead end in terms of vaping. I was going to write an extremely frustrated letter to Evolv back when I have bought my DNA40 accusing them for simply implementing RDTs to vaping the easiest possible way (and sell as revolutionary) instead of doing some thorough research and using their purchase power to get some more suitable alloys made and available for us.
I have never wrote this letter but bought industrial quantity of A120 instead
Unfortunately, Resistancewire.com had no A52 on hand back thenBesides, don't forget that Ni is still pretty good for other applications because if you need a certain initial resistance for any reason it is still Ni which will give the biggest change. It is just you can't build a coil big enough to benefit of it.
Not to mention that sometimes I think that Ti is too good
because its relative big ohm incremental combined with low thermal mass and reasonable specific heat and low thermal conductivity it simply needs too much adjustments/interactions compared to other materials.But why?Cheeky bugger
What did I do?
I was surprised too. And may need to double-check the formulas
But I have to agree that Ni is a sort of dead end in terms of vaping. I was going to write an extremely frustrated letter to Evolv back when I have bought my DNA40 accusing them for simply implementing RDTs to vaping the easiest possible way (and sell as revolutionary) instead of doing some thorough research and using their purchase power to get some more suitable alloys made and available for us.
I have never wrote this letter but bought industrial quantity of A120 instead
Yeah I posted a conspiracy theory a few days back - Evolv chose Ni200 because with its curve, they figured it was harder for other mod makers to implement/copy. They didn't choose a linear wire like Titanium or a NiFe because they figured that was too 'easy'.
No idea if it is true, hence conspiracy theory
It could equally be that Ni200, or at least nickel, was already known to vapers, in the context of those dumb "no resistance" connections people used to use on some atomizers. And hence some vape vendors already carried nickel.Whatever the reason, they could not have chosen worse.
Not to mention that sometimes I think that Ti is too good
Can you elaborate? What do you mean by adjustments and interactions?
But why?
What did I do?
I thought you were referring to how I keep re-posting things you have on your sheet because I forgot to click on other tabs or scroll down
Or maybe that's me projecting my own guilty conscience
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What matters is the ratio of static resistance to coil resistance. For equivalent coils and the same static resistance, that ratio will be much larger for nickel, because the coil resistance is much smaller. I calculated the error E (i.e. the difference of actual temperature and displayed temperature) due to static resistance and I got
E = (T - 20ºC)·Rs/Rc
where
T = displayed temp
Rs = static resistance
Rc = coil resistance at 20ºC
That is: if you add static resistance of x% of the coil resistance, the actual temperature change will be x% higher than the displayed temperature change.
Yeah I posted a conspiracy theory a few days back - Evolv chose Ni200 because with its curve, they figured it was harder for other mod makers to implement/copy. They didn't choose a linear wire like Titanium or a NiFe because they figured that was too 'easy'.
No idea if it is true, hence conspiracy theory
My idea was that it was the only wire available back then for end users. I think it was Temco who sold it. I did my first search around February and no suitable wire was available in sub-industrial quantity but Ni200
I am just guessing here, trying to troubleshoot my Ti issues (why it is a good match for my vaping on a dripper but not so good w/ tanks) but the bottom line is that I think our mods are doing a measurement/fire sequence. Between two measurement Ti can make bigger changes than Ni but could't be cooled down by the liquid as much as Ni.
In other word, you have a cruise control algorithm made for a specific model and you use it for another one equipped with a more powerful engine but far less efficient engine brake.
I thought you were referring to how I keep re-posting things you have on your sheet because I forgot to click on other tabs or scroll down
No comment
Yes exactly - the base resistance is the only factor, TCR is almost completely irrelevant.
Thanks for the formula, that's helpful.
My idea was that it was the only wire available back then for end users. I think it was Temco who sold it. I did my first search around February and no suitable wire was available in sub-industrial quantity bit Ni200
Yeah that's probably most likely - they didn't want to do a Dicodes and try and pioneer a wire at the same time as trying to pioneer a technology.
Which was either smart of them, or short sighted: maybe a requirement for a wire available from only one place would have greatly stunted TCs growth. Or maybe it would have made them a killing, selling "Evolv TC wire" in bucket loads as TC took off anyway.
Perhaps the really smart thing would have been to do both - as Dicodes later did - and enable two modes, Ni200 and OtherWire (Titanium, NiFe), and sell their own wire with its stated advantages, but allow use of generally available Ni200 as well.
But I can understand that might have seemed like too much of an extra burden to take on.
Anyway, didn't happen, and with Titanium sweeping the field, new TCR mods coming out all the time, and NiFe starting to reach a range of vendors, hopefully the impact of Ni200 will be short lived
Yeah very true - I touched on this yesterday, saying that we've been looking at mod accuracy in terms of being mΩ granular, but that is only half the story in terms of mods. Next up comes its power management algorithm.
Unfortunately that's far harder to quantify. All we can try and do is empirically test it - what accuracy does Mod X achieve with a certain wire type, and is that different to its accuracy with other wire types?
We know for sure there's big differences in the capabilities of the power algorithms - Evolv, Yihi and Dicodes being amongst the best, SXK amongst the worst, and others in between.
Sadly the issue has been clouded quite a bit by what appears to be some lower-end manufacturers deliberately under-heating coils - Joyetech, Eleaf, Smok. Perhaps so they never fail a cotton burn test.
Though even Yihi with their new Titanium modes have similar issues. There does seem to be a pattern with Titanium modes - always underheating, even when the Ni200 mode on the same mod does not (or not to the same extent.) Could that be related to what you're saying? I'm not sure, but it bears further testing.
So it seems that NiFe52 is the winner at least in theory.
I will be patient this time and wait for NiFe52. I won't rush in and buy some NiFe70 in thicker gauge cause I'm still using my Resistherm wire.
If I understand it correctly, in theory if I use 120-130C at yihi chips and 150-160C at DNA40 for Resistherm, then for NiFe52 I'll need to use 140-150 for yihi and 170-180 for DNA40.
Am I close or I'm confused?
Thanks again, can't wait for NiFe52 and I am glad I see more vendors to get in the NiFethal game...
Cheers!
I will be patient this time and wait for NiFe52. I won't rush in and buy some NiFe70 in thicker gauge cause I'm still using my Resistherm wire.
If I understand it correctly, in theory if I use 120-130C at yihi chips and 150-160C at DNA40 for Resistherm, then for NiFe52 I'll need to use 140-150 for yihi and 170-180 for DNA40.
Am I close or I'm confused?
Thanks again, can't wait for NiFe52 and I am glad I see more vendors to get in the NiFethal game...
Cheers!
I'm pretty sure one major reason Evolv settled on Ni200 was simple a matter of widespread availability. For one thing, just about every pre-built coil manufacturer had huge supplies of it, since most non-TC coils are still welded NR-R-NR, with Ni200 making up the NR (non-resistance) legs.
Ironically, the widespread use of Ni200 to prevent "hot legs" led to coil designs that tend to suck when retrofitted to pure Ni200 TC heads.
Ironically, the widespread use of Ni200 to prevent "hot legs" led to coil designs that tend to suck when retrofitted to pure Ni200 TC heads.
I
On this, I'm not sure if there is a power algorithm utilized in tc mods but I have spent a lot of time watching displayed power while vaping both the Snow Wolf and Evic, both with Ni and Ti.
The Evic is by far a smoother operator in terms of power regulation with both types of wire and regulates power in .1w increments if I keep my draw effort very consistent. The wolf, with the same atty, regulates power in in wider increments. Sometimes 5w up and down even with consistent draw effort. A pulsy temp control for sure, especially with Ni.
Maybe the Evic has a faster processor/regulator? Less latency? Faster transient response? Not sure...hmmm.
Specifically, when I refer to power algorithms here I am referring to how aggressively the mod provides/removes power based on tcr curves, not how accurate it displays temp.
Would the optimum power management scenario for a Ni/Ti mod be separate power algorithms for each wire type based on tcr at any given temp? Maybe, but if res monitoring and power regulation is fast enough to track the curve is that really necessary? Hmmm.
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Sorry to interrupt all the serious business and thinking... but anyone still wanting to play with stainless steel, fast tech has thrown their hat in the ring. 316L in every thickness usable for coil making, starting under $3.
Found 13 316L Stainless Steel Heating Wire at FastTech - Worldwide Free Shipping
Found 13 316L Stainless Steel Heating Wire at FastTech - Worldwide Free Shipping
Probably a bigger reason they chose it is because of its TCR. The mod doesn't have to be as accurate with ohm its reading (or as precise) as it would for, say, SS or even Ti. It's kind of like a digital scale. 1.1g on one scale isn't as precise as 1.13g on another. And that scale is nothing compared to a scale that can read to 5 decimal places (where draft shields and very expensive calibration weights are required).
Another reason is that nickel is one of the most accurate elements for measuring temperatures below 600F (hence the cut-off). Other elements can do it, but they aren't as accurate for our temperature range (or would require much more accurate ohm measurements). Platinum is used in commercial RTD's, but it's better for higher temperatures than we use. Nickel's TCR becomes non-linear above 600F as well. Not to mention there is an issue with possible graphite accumulation at that temperature too. All of these things combined make a 600F cut-off obvious.
Theoretically we can do TC with Kanthal. All we need is an ohm reader that is precise (and accurate) enough to read to 5 (maybe more) decimal places and do it consistently. Such a reader would be very expensive to implement in a commercial off-the-shelf mod. And even if you could, small static resistance changes could throw the values way off. The designers and engineers would have a lot to compensate for and that's hard. With Nickel, the TCR is high enough that you can be off a little and not throw the temperature that far off.
Thank God!
Received stainless steel from Fasttech today and I can finally build coils the way I used to do with kanthal again!
Really guys, I HATE using Ni and Ti!!!
I was kidding myself the (flimsy looking) end result was better because it gave me the opportunity to use TC but really, what a drag!
SS does non spaced coils without being picky, I can let it glow to check if it's heating evenly and it just feels right. No more Ni and Ti for me. Ever!
Received stainless steel from Fasttech today and I can finally build coils the way I used to do with kanthal again!
Really guys, I HATE using Ni and Ti!!!
I was kidding myself the (flimsy looking) end result was better because it gave me the opportunity to use TC but really, what a drag!
SS does non spaced coils without being picky, I can let it glow to check if it's heating evenly and it just feels right. No more Ni and Ti for me. Ever!
Ooooh well, now we want to know everything about your wire, build and settings.
That's exactly what we've been discussing the last few days. Ni200 is not the most accurate material for TC vaping. It is in fact the least accurate material.
The most accurate material - or to use @vapealone 's generalisation, the most sensitive material, is Titanium. Shortly followed by NiFe52, then NiFe70, then Resistherm, then Stainless Steel 304, then Stainless Steel 316, then Kanthal DH, then, finally, propping up the table like a drunk at closing time, is our friend Ni200.
The TCR is high but the resistance is so very low that it is by far the least sensitive and the least accurate. At 250°C, 3.3 times less sensitive than Titanium, 3 times less than NiFe52, and only 70% as sensitive as SS316.
Remember that base resistance is just as critical as the TCR - I wrote about that at length yesterday, here. We should not be comparing, say, a 0.1Ω Ni200 coil to a 0.1Ω Titanium or SS coil. We should be comparing a 0.1Ω Ni200 coil to a 0.50Ω Titanium coil and a 0.70Ω SS coil. Whatever coil type is chosen as the comparison, Ni200 will be roughly five times lower resistance than Titanium but only have 1.5x the TCR, and seven times lower resistance than Stainless Steel with only 4 - 5 times greater TCR.
This is what vapealone's Temperature Sensitivity generalisation already shows us in the general case, and I am going to do a Wire Comparison Chart that does the specific case, assuming certain standard builds.
Nickel does have a high TCR that make it potentially very accurate, given a high enough resistance. But this cannot apply for TC vaping because of the resistances we build at. I don't know the base resistances of the nickel in RTDs and the like, but I'm told they're much higher than we can use as coils.
If we could build 0.50Ω Ni200 coils it would indeed be most accurate, but that's not a practical or desirable or even achievable coil build. Even with 30G wire, it's 24 x 3mm wraps
Hence wondering about why Ni200 was chosen. Its low resistance makes building inflexible, limited and annoying. Its low resistance makes theoretical accuracy poor. It has the greatest risk for people with sensitivities. It can't be dry burnt.
Conspiracies aside, the only plausible reason why it was chosen is that it was already known to vapers and vape vendors in the context of 'No Resistance' connections.
But that aside, they really could not have chosen a worse wire.
It's now been done. Well, not TC. But 'dry hit prevention' has been implemented in the new iJoy by Asolo, and we've confirmed it uses resistance to do it.
It is, as you would expect, highly sensitive to the slightest amount of varying SR in the atomizer or build. But as all they need to do is detect the difference between "normal vape" and "dry hit", it does sort of work. Quite impressive. But my current feeling is not reliable enough to be a game changer - but I'm still in the process of testing it thoroughly.
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