TC beyond Ni200: Nickel Purity, Dicodes; Ti, SS, Resistherm NiFe30; Coefficient of Resistance

[JimScotty0]

vaping with mixed wires is not TC vaping, it's power only vaping. You may think you are in TC but you are not, so why bother.

I would disagree with that statement. I have had good success with Ti/Ni, Ti/Kanthal A1, Ni/Kanthal A1, Invar36/Ti, and Invar36/Kanthal A1. You need to dial in the TCR with a water test to start out, but it does work without burning cotton too. You just need to calculate out the 2 wires and gauges and SE does help out with that by plugging in the 2 or more wires into the Wire Wizzard. I have done it for months but these days I am sticking to Ti since it produces a great vape. This was just experimenting on just what were the possibilities.

 

[vapealone]

On a side note I wonder if Vapealone would consider a brief (if that's possible) how to Tutorial/explanation for his active worksheet. That would help those of us who are not math & spread sheet wizards

1.,Input data (Material tabs)

I have used input data from various sources includes different experiments (Ti, S/S) and manufacturers' material data sheets (the rest). These data can be found under the different material tabs. This material pages shows the type of the input data too. (E.g. for several material it is TFR, for others it is resistance measured at given temperature). From this input data I have calculated the corresponding missing data. You can also find links to the source on this pages. (and on every pages).


2., Output data ( ρ(T), TFR, TCR)

I have used different functions to create approximate ρ(T), TFR, TCR curves for each of the material within the working range in order to fill the gaps between the input data. The result is shown on these tabs. Accuracy can also be checked for these tabs shows approximated values only meanwhile material tabs shows straight input data and data simply calculated from the input data.

3., CSV tab is an extract of the above for DNA200 use

Notes:

AFAIk, there is no universal formula to determine resistance or resistance changes of any material at a given temperature but approximative formulas utilising empirical coefficients.
TCR is the most common empirical coefficient to be used for linear approximation as per this:

In this formula TCR (ɑ) s determined by experiment.

E.g.:
Your material has ρ(0)=1 ohm resistance at a given T(0) temperature and ρ(T)=2 ohm resistance at an elevated T temperature then you can calculate TCR as:

(ρ(T)/ρ(0)-1)/(T-T(0))= ɑ (TCR)

And within the T(0)-T temperature range with this TCR you can approximate the temperature using the formula above.

However, it is a linear approximation that can be extremely off between the endpoints. It is nothing more than plotting two points on a curve, draw a line between and say, everything between the two points is on the line instead of the curve.
Besides, it can be completely useless outside of the range so you need to know the two endpoints when using TCR.

And this is the main point of my TCR tab.
Unless nothing else indicated, the TCR you can find listed here and there refers to 0-100°C. Beside this so called nominal TCR the only thing I have found listed (and indicated) somewhere once was TCR referring to 20-100°C.
None of these TCRs are extremely informative for our vaping range is (100)200-300°C. That is why I calculated/approximated TCRs between 20°C and temperature points within our temperature ranges.

Bottom line:

On a DNA device, normalised (or not?) TFR values (based on experiments) can be used to calculate (approximate) average temperature and we don't have to worry about TCRs and ranges.
On devices with TCR settings, the best thing you can do is to pick a TCR value that refers to the range between room temp (20°C) and your target temp.
And in this case, even though the temp reading between the endpoints won’t be super accurate the endpoints will be ok and this is what matters.
Of course, IMO

 

[vapealone]

Vaping with mixed wires is not TC vaping, it's power only vaping. You may think you are in TC but you are not, so why bother.

I have to join the guys above:
You may think you know what TC vaping is, but you don't.

TC vaping is nothing else than using resistance reading to calculate/approximate average coil temperature and regulate output accordingly if necessary.
And yes, the factors/coefficients needed for this approximations can be determined for mixed coils with sufficient accuracy you like it/beleive in it or not.
It is not about belief, or cult (TC vs power vaping) but very basic science. Even I can do this

 

[vapealone]

And let me prove it.
The gif below shows the resistance change of a simple twisted wire of two different materials
Wire 1 (Green): Cold ohms= 1 ohm, TCR=0.00, -> live ohms = 1ohm for TCR=0
Wire 2 (Red) : Cold ohms= 1 ohm, TCR=0.005, -> live ohms are increasing linearly for TCR is constant
Mixed wire (Blue) Cold ohms= 0.5 ohm, TCR (can be calculated, but not constant!) -> live ohms are increasing NON-linearly (in fact hyperbolically) for TCR is NOT constant.
And this is it.
Note: I have used identical cold ohms and flat TCR for the sake of simplicity. The maths would work just fine with different values.

P.S.:
If the gif can't be seen, check here:
Mixed wire gif

 

[vapealone]

deleted, for not working

 

[cigatron]

Great animated graph @vapealone!!

But why would the .005 tcr of wire #1 change when hybrided with a the .000 tcr of wire #2? It doesn't literally, but the calculated TOTAL TFR does based on ohms law for total circuit res for parallel resistors, as I stated in one of my previous posts.

Always great to have visual representation.

 

[vapealone]

Great animated graph @vapealone!!

But why would the .005 tcr of wire #1 change when hybrided with a the .000 tcr of wire #2? It doesn't literally, but the calculated TOTAL TFR does based on ohms law for total circuit res for parallel resistors, as I stated in one of my previous posts.

Always great to have visual representation.

its not the wire TCR that changes but the resultant TCR for:

R(resultant) = 1/((1/R1)+(1/R2)) as you mentioned and:

In our case, 1/R1 is constant, and 1/R2 is decreasing hyperbolically for the any linear f(x)=ax 1/f(x) will be a hyperbola (a=constant)
A constant value + a hyperbolically decreasing curve will yield another decreasing hyperbolic function.
And the reciprocal of this decreasing hyperbolic function will be an increasing hyperbolic function that means the resistance change of this mixed coil can't be or shouldn't be determined a single constant TCR value for the sake of accuracy.

In this case, same goes with the TFR. Actually, the TFR curves would look excatly the same as the resistance curves, for ρ(0)= 1 and TFR= ρ(T)/ρ(0) and in our case=ρ(T)

 

[cigatron]

its not the wire TCR that changes but the resultant TCR for:

R(resultant) = 1/((1/R1)+(1/R2)) as you mentioned and:

In our case, 1/R1 is constant, and 1/R2 is decreasing hyperbolically for the any linear f(x)=ax 1/f(x) will be a hyperbola (a=constant)
A constant value + a hyperbolically decreasing curve will yield another decreasing hyperbolic function.
And the reciprocal of this decreasing hyperbolic function will be an increasing hyperbolic function that means the resistance change of this mixed coil can't be or shouldn't be determined a single constant TCR value for the sake of accuracy.

In this case, same goes with the TFR. Actually, the TFR curves would look excatly the same as the resistance curves, for ρ(0)= 1 and TFR= ρ(T)/ρ(0) and in our case=ρ(T)

Well put, better than I could ever express. Glad you're here @vapealone !

Here's a new related subject/question, for this thread anyway:

There are new-ish tc mods available now which offer auto detection of the heating wire's tcr value. I have an iJoy Asolo which does this and it works quite good for temp protecting kanthal and stainless steels. It also has dedicated ni and ti modes but it is not necessary to use them for temp protect, only for temp control where one selects a preferred temp and power level.

The Asolo requires the user to take a few 2 sec. or longer puffs in power mode to determine wire behavior before flipping over to temp protect mode (iJoy flavor mode).
I am guessing that the auto tcr detection is accomplished using an algorithm based on res rise over time with reference to selected wattage. Any thoughts on auto tcr detection?

 

[vapealone]

Well put, better than I could ever express. Glad you're here @vapealone !

Here's a new related subject/question, for this thread anyway:

There are new-ish tc mods available now which offer auto detection of the heating wire's tcr value. I have an iJoy Asolo which does this and it works quite good for temp protecting kanthal and stainless steels. It also has dedicated ni and ti modes but it is not necessary to use them for temp protect, only for temp control where one selects a preferred temp and power level.

The Asolo requires the user to take a few 2 sec. or longer puffs in power mode to determine wire behavior before flipping over to temp protect mode (iJoy flavor mode).
I am guessing that the auto tcr detection is accomplished using an algorithm based on res rise over time with reference to selected wattage. Any thoughts on auto tcr detection?

Sorry, I got no idea. Considering that Kanthal has no (significant) resistance change within our range this feature is most likely utilizes some other aspect I got no information about.

 

[cigatron]

Sorry, I got no idea. Considering that Kanthal has no (significant) resistance change within our range this feature is most likely utilizes some other aspect I got no information about.

I can see kanthal builds rise from ambient to tp .01 ohm on the display. Apparently that's enough to indicate a dry wick.

 

[vapealone]

I can see kanthal builds rise from ambient to tp .01 ohm on the display.

What is tp .01?
BTW:
Review: The Asolo from Shenzhen iJoy Technology

 

[AtmizrOpin]

Gotta .... in here. Maybe someone can chime in here with an answer. Got a dual 24 gauge 8 wrap nife48 build on my velocity. It's acting as if the TCR from WW is way too low, 600 Vapes like 400. Switch over to the DNA 200's stock Ni200 profile, 480 feels like 480. Cold resistance is .09. Triple checked my cold ohms, thinking that was culprit, nope. Grub screws tiiiiiigggghhhhht! So that isn't it. Coils are spaced. This build, out of many of my nife builds is the only nife build doing this. All other nife builds vape as expected when on nife52 TCR from WW. What the effff.

 

[dwcraig1]

I just did something similar earlier, using SE curve for NiFe52. Twisted 26 gauge NiFe 48 coming in @ 0.08 cold. Verticals, doing well. Also with Aromamizer on DNA200.

 

[notarobot]

@vapealone: it's not possible to calculate a "combined" TCR for two parallel wires. This works only if both wires are identical. Having one wire with TCR = 0 is another special case and allows to calculate the temperature of the other wire with a TCR > 0, but not both. In general (both wires have TCR > 0), even that isn't possible. Of course you can calculate the resistance for the parallel wires from a given temperature, but TC needs the other way round and that doesn't work: given a resistance, you cannot calculate the individual wire temperatures. They will be different anyway! In that sense, WharfRat1976's statement is correct: mixed wires do not work with TC.

 

[cigatron]

What is tp .01?
BTW:
Review: The Asolo from Shenzhen iJoy Technology

Sorry, poorly written. The Asolo has a "Dry Wick" icon that flashes in "Flavor Mode". With kanthal builds the display shows a .01 ohms increase from cold res to the point where the dry wick icon begins to flash.

 

[cigatron]

@vapealone: it's not possible to calculate a "combined" TCR for two parallel wires. This works only if both wires are identical. Having one wire with TCR = 0 is another special case and allows to calculate the temperature of the other wire with a TCR > 0, but not both. In general (both wires have TCR > 0), even that isn't possible. Of course you can calculate the resistance for the parallel wires from a given temperature, but TC needs the other way round and that doesn't work: given a resistance, you cannot calculate the individual wire temperatures. They will be different anyway! In that sense, WharfRat1976's statement is correct: mixed wires do not work with TC.

So are you saying the hybrided coils have no tcr? That they have no change in res from cold to vaping temps? I don't think that's what you're saying, but at the same time you are saying they can't be temp controlled.

If hybrided coils have a combined tcr value and resulting tfr value then common sense tells me that they can be accurately temp controlled at any selected vaping temp by adjusting tcr settings.

I believe @vapealone clearly shows in his animated graph that using one wire with a .000 tcr value in a hydrided coil causes a hyperbolic tfr and I believe if that wire had been >.000 the hyperbola would have been reduced, resulting in a higher total tfr.

In the end I believe if both wires had a >.000 tcr, same tcr or not, the coil would be better for tc.

 

[vapealone]

@vapealone: it's not possible to calculate a "combined" TCR for two parallel wires. This works only if both wires are identical. Having one wire with TCR = 0 is another special case and allows to calculate the temperature of the other wire with a TCR > 0, but not both. In general (both wires have TCR > 0), even that isn't possible. Of course you can calculate the resistance for the parallel wires from a given temperature, but TC needs the other way round and that doesn't work: given a resistance, you cannot calculate the individual wire temperatures. They will be different anyway! In that sense, WharfRat1976's statement is correct: mixed wires do not work with TC.

It is possible
I have just done. And the fact that one of the TCR is 0 in my calculation doesn't matter a bit.

And do you know why?
Because TCR is not some inherent property of a material, at least not in universal terms. Assuming that there is such a thing that material or matter, that is.

TCR is nothing else than a fabricated coefficient for linearly approximate temperature between two known points. And known points means values obtained via measurement.

From this point of view, it doesn't matter that the material is pure element, or a contaminated material (i.e non pure element like TiGr1, Ni200), or an alloy or different materials combined.

You can define TCR for whatever you want.

What does matter is their temperature and resistance as you pointed out.

I admit, that in case of a hybrid coil, the temperature of the materials won't be 100% identical, let alone uniform but they will be close enough for our purpose.

Not to mention, that temperature wont be uniform for the simplest single coil either, especially if it is wicked, saturated and evaporation is happening. Let alone temperature of more exotic built of the very same material. (twisted, clapton and above)

Bottom line: from the resistance you can calculate the temperature just fine.

Note:
My avatar shows a Kanthal/Ni200 hybrid clapton
It is more likely that actual temperature of any given point of it is not 100% identical with neither a Kanthal nor an Ni200 Clapton or a single coil built but the average temperature is close enough for our purpose.

We are approximating here, nothing else.

BTW:
I have to admit, I was quite disappointed when found out that Evolv's praised true Ni200 curve is nothing else than a few segments poly-line more likely based on some datasheet like this. And they didn't even bother to fit some curve on it for better approximation between the points but drew straight lines.
But later realised that there is no point to do so for there are way bigger uncertainties in our systems.
And that is ok. It is not a Mars mission.
It is just some plain and rough RTD application.

P.S.:
I don't say that this approximation is 100% accurate but I do say that it is good enough.
That is why I mentioned Evolv's true Ni200 curve. Nothing is 100% but it doesn't have to.
You just need to know what is behind the over-mystified and over-hyped marketing façade and make your call, that is.

 

[vapealone]

Sorry, poorly written. The Asolo has a "Dry Wick" icon that flashes in "Flavor Mode". With kanthal builds the display shows a .01 ohms increase from cold res to the point where the dry wick icon begins to flash.

Kanthal A-1 do have measurable (in the realm of vaping gears) resistance change but it starts around 500°C (932°F)
If this 0.01 ohm increase is happening below that temperature than my bet is on the coil/atty/connector/wire combo where you can find components with some measurable IR and higher than A-1 TCR

 

[Croak]

Kanthal A-1 do have measurable (in the realm of vaping gears) resistance change but it starts around 500°C (932°F)
If this 0.01 ohm increase is happening below that temperature than my bet is on the coil/atty/connector/wire combo where you can find components with some measurable IR and higher than A-1 TCR

And the initial resistance with Kanthal may increase just due to disparate thermal expansion of the various connection points as the atomizer is fired.

 

[cigatron]

Kanthal A-1 do have measurable (in the realm of vaping gears) resistance change but it starts around 500°C (932°F)
If this 0.01 ohm increase is happening below that temperature than my bet is on the coil/atty/connector/wire combo where you can find components with some measurable IR and higher than A-1 TCR

And the initial resistance with Kanthal may increase just due to disparate thermal expansion of the various connection points as the atomizer is fired.

Ok I get it. But I'm not giving up on how the Asolo accomplishes temp protect with kanthal.

Studying up on some of my 33yr old EE coarse books on FL (inductive reactance) and how heat affects frequency in inductive circuits. If iJoy is using the coil (known cold res)(inductor) while providing a fixed frequency in the coil circuit they could be measuring frequency change with rise in inductor (coil) temp.....maybe. It's killing me to not know!