TC beyond Ni200: Nickel Purity, Dicodes; Ti, SS, Resistherm NiFe30; Coefficient of Resistance
- Thread starter TheBloke
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Well, you're adding another connection point and some potential increased resistance. Extra static resistance isn't that big of a deal (unless it's a very large amount). Just make sure your baseline (cold) resistance isn't fluctuating.
Regarding Crazy Wire's "NiFe": We have confirmation of another customer (@RingaDing ) who received SS 304. So it's not just me, it's the entire batch. Absolutely unbelievable.
Let's assume it's merely total incompetence and not a deliberate attempt to deceive. For now anyway.
Let's assume it's merely total incompetence and not a deliberate attempt to deceive. For now anyway.
I will defenitly join in posting a complaint to the Koopor site. I hope it is something that can be adjusted in the firmware and not hard wired into the chip.I already went to the Kooportech website and put in a strong suggestion that they update the firmware for a slower menu action. It might be a good idea if they got a flood of similar suggestions.
Duane
Incompetence I reckon but one never knows I guess! At least they are consistent!
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Thanks guys. Thought it best to ask. I'll check the resistance with and without the heat sink in the morning when its nice and cold (room temp) and see if there is much difference.
How much would you say is too much change?
I have noticed that after using a fresh coil for a day or so the resistance does vary by about .02 or so from the resistance when it was fresh. I just assumed that was the coil working out any minor hot spots or whatever on a fresh coil since the leads and everything are still tight.
How much would you say is too much change?
I have noticed that after using a fresh coil for a day or so the resistance does vary by about .02 or so from the resistance when it was fresh. I just assumed that was the coil working out any minor hot spots or whatever on a fresh coil since the leads and everything are still tight.
Here you go @BrentMydland - something I had been meaning to write about for a little while anyway.
TC Inaccuracy from Atomizer Resistance - Static and Variable
Static Resistance (SR)
SR = any amount of resistance read by the mod which is not accounted for by the wire in the coil itself, and which is always present (static)*.
Therefore it is primarily the resistance of the atomizer itself - its positive pin, its positive and negative block/posts, and any intermediate metal. The positive is usually the higher resistance, as the negative goes through the body of the atomizer which is much thicker and so lower resistance (though the positive is often partly brass or copper to balance this out.)
SR can possibly also include the wiring to the mod's 510 and the 510 itself, depending on whether this has been measured and automatically subtracted by the mod/chip maker. (Users of the DNA 200 can adjust this themselves via eScribe's Mod Resistance setting.)
The impact of static resistance (SR) depends entirely on the base resistance of the coil. It is irrespective of the TCR, and therefore also, technically, of the wire used.
However as the wires we use have different resistivity, in practice the wire used does impact the likely effect from SR. Ni200 coils are almost always very low resistance and thus experience high inaccuracy from SR, where Stainless Steel resistance is almost always much higher and therefore much lower inaccuracy, and so on. Titanium and NiFe are in between, with Titanium less affected than NiFe.
I consider 0.01Ω to be the maximum amount of static resistance I will willingly accept. Most of my tanks that I have checked are no more than 0.005Ω, but I haven't been particularly bothered to test them all quickly. I'll do it over time, as I feel like it, and I wouldn't stop using a nice tank if I did find it was more than 0.01Ω. I would though see if I could improve it. I have already improved a few tanks by replacing stainless parts with brass, in particular my Squape Rs clones. My best tanks for SR are my authentic Aqua v2s, which have an all-copper positive path that I measured as 0.0004Ω!
As mentioned, the inaccuracy caused by SR is relative to the base resistance of the coil. It is also relative to the target temperature - it is best expressed as a % of the target temperature.
Here's the inaccuracies caused by 0.01Ω of static resistance for the following coil base resistances as a % of the target temperature, and actual inaccuracy at target temperature = 230°C (446°F)
I have expressed the inaccuracies as + numbers, by which I mean they are the amount by which the mod will overheat the coil. So a 0.08Ω coil with 0.01Ω SR (read by the mod as 0.09Ω) set to 230°C will actually be heated to 256.25°C, which is +11.41% of the target temperature.
The percentages change linearly with SR. So 0.02Ω SR will cause +22.83% inaccuracy with the 0.08Ω coil, and +3.04% with the 0.60Ω coil. They also change linearly with decreasing base resistance - for example note 0.40Ω being half the inaccuracy of 0.20Ω.
As SR always leads to overheating the coil, the natural fix is to set our target temperature lower than we want to achieve. To compensate, we can simply set it lower on the mod by the amount indicated above - eg if we know we have 0.01Ω SR on a 0.20Ω coil, and our actual target temperature is 230°C, we set the mod to 220°C. Rounding as appropriate to get the nearest °C or °F setting the mod will do.
* The exact definition of the 'static' in SR is: present at the time the cold base resistance of the coil is measured by the mod, and then present inthe same amount throughout all subsequent vapes until the next base resistance measurement.
If the resistance is not present during one or the other occasions, or its amount changes, then that (or some part of it at least) becomes Variable Resistance:
Varying Resistance (VR)
VR = any amount of non-coil resistance which comes and goes, for example caused by the atomizer not being screwed on as tightly as possible to the mod, or by screws not being tightly secured onto the coil, loose posts, or any other resistance that cannot be guaranteed at a single figure.
VR should be avoided wherever possible because it is unpredictable and thus cannot be easily compensated for.
VR affecting the base/cold coil resistance reading
Let's look at a 0.01Ω varying resistance that is there when the cold resistance is read, and then disappears later; perhaps the atomizer was not fully tightened at first and was then adjusted later.
It will not be removed, and will cause ongoing inaccuracy, on "Set Resistance" chips such as the Yihi, Dicodes, etc - or on the DNA 40/200 if the "lock resistance" feature is used.
We could regard base readings taken on non-cold atomizers (eg moved from another mod and not cooled) as also being VR. Well in fact it is VR, just of a different cause to the mechanical components we normally associate with SR/VR.
VR not present during the base/cold coil resistance reading but then appearing during vapes
For this case, let's assume the base/cold coil resistance was read correctly but then 0.01Ω VR suddenly appears in the middle of a vape. For simplicity, this example assumes there's not also any SR:
A 0.20Ω coil, read correctly by the mod as 0.20Ω, but then exhibiting +0.01Ω VR during the vape, will have an inaccuracy of -14.3°C; it will be underheated, not overheated as in the SR cases.
This case would include situations where the atomizer was accidentally unscrewed a touch from the mod, or otherwise became slightly looser - causing the base reading of the coil to increase.
Evolv's DNA Refinement can also help to correct this: as well as detecting when the base resistance of the coil goes down, it can also detect when it goes up. I think this takes a little longer, as the mod has to be sure the resistance rise is due to the coil adjusting, and not because the coil has been heated. When I tested this on my DNA 40 by half-unscrewing an atomizer, it took about 15 minutes of idle time (no vaping) before it refined the resistance upwards.
Summary:
As an aside, it's this over-heating of the coil - and thus under-setting of our target temp - that explains why it was common in the earlier days of TC to see YouTubers like Busardo talk about "this tank tastes burnt at more than 300°F, while this RDA needs 450°F". The joys of Ni200
TC Inaccuracy from Atomizer Resistance - Static and Variable
Static Resistance (SR)
SR = any amount of resistance read by the mod which is not accounted for by the wire in the coil itself, and which is always present (static)
Therefore it is primarily the resistance of the atomizer itself - its positive pin, its positive and negative block/posts, and any intermediate metal. The positive is usually the higher resistance, as the negative goes through the body of the atomizer which is much thicker and so lower resistance (though the positive is often partly brass or copper to balance this out.)
SR can possibly also include the wiring to the mod's 510 and the 510 itself, depending on whether this has been measured and automatically subtracted by the mod/chip maker. (Users of the DNA 200 can adjust this themselves via eScribe's Mod Resistance setting.)
The impact of static resistance (SR) depends entirely on the base resistance of the coil. It is irrespective of the TCR, and therefore also, technically, of the wire used.
However as the wires we use have different resistivity, in practice the wire used does impact the likely effect from SR. Ni200 coils are almost always very low resistance and thus experience high inaccuracy from SR, where Stainless Steel resistance is almost always much higher and therefore much lower inaccuracy, and so on. Titanium and NiFe are in between, with Titanium less affected than NiFe.
I consider 0.01Ω to be the maximum amount of static resistance I will willingly accept. Most of my tanks that I have checked are no more than 0.005Ω, but I haven't been particularly bothered to test them all quickly. I'll do it over time, as I feel like it, and I wouldn't stop using a nice tank if I did find it was more than 0.01Ω. I would though see if I could improve it. I have already improved a few tanks by replacing stainless parts with brass, in particular my Squape Rs clones. My best tanks for SR are my authentic Aqua v2s, which have an all-copper positive path that I measured as 0.0004Ω!
As mentioned, the inaccuracy caused by SR is relative to the base resistance of the coil. It is also relative to the target temperature - it is best expressed as a % of the target temperature.
Here's the inaccuracies caused by 0.01Ω of static resistance for the following coil base resistances as a % of the target temperature, and actual inaccuracy at target temperature = 230°C (446°F)
- 0.08Ω: +11.41% | +26.25°C
- 0.12Ω: +7.61% | +17.50°C
- 0.15Ω: +6.09% | +14.00°C
- 0.20Ω: +4.57% | +10.50°C
- 0.40Ω: +2.28% | +5.25°C
- 0.60Ω: +1.52% | +3.50°C
I have expressed the inaccuracies as + numbers, by which I mean they are the amount by which the mod will overheat the coil. So a 0.08Ω coil with 0.01Ω SR (read by the mod as 0.09Ω) set to 230°C will actually be heated to 256.25°C, which is +11.41% of the target temperature.
The percentages change linearly with SR. So 0.02Ω SR will cause +22.83% inaccuracy with the 0.08Ω coil, and +3.04% with the 0.60Ω coil. They also change linearly with decreasing base resistance - for example note 0.40Ω being half the inaccuracy of 0.20Ω.
As SR always leads to overheating the coil, the natural fix is to set our target temperature lower than we want to achieve. To compensate, we can simply set it lower on the mod by the amount indicated above - eg if we know we have 0.01Ω SR on a 0.20Ω coil, and our actual target temperature is 230°C, we set the mod to 220°C. Rounding as appropriate to get the nearest °C or °F setting the mod will do.
* The exact definition of the 'static' in SR is: present at the time the cold base resistance of the coil is measured by the mod, and then present inthe same amount throughout all subsequent vapes until the next base resistance measurement.
If the resistance is not present during one or the other occasions, or its amount changes, then that (or some part of it at least) becomes Variable Resistance:
Varying Resistance (VR)
VR = any amount of non-coil resistance which comes and goes, for example caused by the atomizer not being screwed on as tightly as possible to the mod, or by screws not being tightly secured onto the coil, loose posts, or any other resistance that cannot be guaranteed at a single figure.
VR should be avoided wherever possible because it is unpredictable and thus cannot be easily compensated for.
VR affecting the base/cold coil resistance reading
Let's look at a 0.01Ω varying resistance that is there when the cold resistance is read, and then disappears later; perhaps the atomizer was not fully tightened at first and was then adjusted later.
- Two examples, two different atomizers on two different identical mods
- The atomizers themselves have 0.01Ω SR
- Coil One is really 0.20Ω, but the SR + VR causes the mod to read it as 0.22Ω.
- Coil Two is really 0.40Ω, but the SR + VR causes the mod to read it as 0.42Ω.
- The user has a desired target temperature of 230°C
- Some vapes are taken before the VR disappears. There is 0.02Ω SR+VR in place, therefore the inaccuracies are:
- Coil One, 0.20Ω : +9.13% = +21.00°C = heated to 251°C on a 230°C setting
- Coil Two, 0.40Ω : +4.57% = +10.50°C = heated to 240.5°C on a 230°C setting
- These are just the same as if there had been 0.02Ω SR.
- Now the VR disappears, but the mod still thinks the base resistance is 0.42Ω
- Coil One, 0.20Ω : Will be heated to 265°C = an inaccuracy of +35°C
- Coil Two, 0.40Ω : Will be heated to 247°C = an inaccuracy of +17.5°C
- The fact that the VR has gone makes things a lot worse, an extra 50% inaccuracy compared to when it was there, because now the base resistance reading is out of sync with the in-vape resistance readings.
It will not be removed, and will cause ongoing inaccuracy, on "Set Resistance" chips such as the Yihi, Dicodes, etc - or on the DNA 40/200 if the "lock resistance" feature is used.
We could regard base readings taken on non-cold atomizers (eg moved from another mod and not cooled) as also being VR. Well in fact it is VR, just of a different cause to the mechanical components we normally associate with SR/VR.
VR not present during the base/cold coil resistance reading but then appearing during vapes
For this case, let's assume the base/cold coil resistance was read correctly but then 0.01Ω VR suddenly appears in the middle of a vape. For simplicity, this example assumes there's not also any SR:
A 0.20Ω coil, read correctly by the mod as 0.20Ω, but then exhibiting +0.01Ω VR during the vape, will have an inaccuracy of -14.3°C; it will be underheated, not overheated as in the SR cases.
This case would include situations where the atomizer was accidentally unscrewed a touch from the mod, or otherwise became slightly looser - causing the base reading of the coil to increase.
Evolv's DNA Refinement can also help to correct this: as well as detecting when the base resistance of the coil goes down, it can also detect when it goes up. I think this takes a little longer, as the mod has to be sure the resistance rise is due to the coil adjusting, and not because the coil has been heated. When I tested this on my DNA 40 by half-unscrewing an atomizer, it took about 15 minutes of idle time (no vaping) before it refined the resistance upwards.
Summary:
- Varying Resistance: if you've got it, check your atomizer/mod and fix it; it is, as the name suggests, variably impactful and there's no good reason to put up with it.
- It might underheat, it might overheat, and either way it will do much more damage than SR
- Static Resistance: every atomizer has some amount, and unless you're using Ni200 it's rarely a big deal
- It applies fairly minimally for most resistances you are likely to build to with Titanium, Stainless Steel, and (to a lesser extent) the NiFes.
- With NiFe70 single coil you might get down to 0.15Ω or so, and thus be subject to 6%, or around 14°C at common TC temps.
- NiFe52 single coil should not usually be worse than 4.5%, or 10°C at 230°C/450°F, and will often be better (my standard coil of NiFe52 will be 0.30Ω)
- It applies fairly minimally for most resistances you are likely to build to with Titanium, Stainless Steel, and (to a lesser extent) the NiFes.
- SR maximums: I consider 0.01Ω to be a good guideline maximum: with at most this a mount of SR, at the resistances I build, I don't have to think about offsets.
- I set 235°C every time and my vapes are pretty consistent (on accurate mods) regardless of the atomizer in use
- If you've got more than 0.01Ω you can use the figures in this post to decide how bad it is at your usual base resistances and either try to reduce it, or just account for it in your target temperatures.
- Adjusting for SR: In all cases of high(er) SR, the result will always be that the mod over-heats the coil
- So it can be counteracted by lowering your target temperature by the amount indicated by the inaccuracy
- Remember that the inaccuracy is a % of the target temperature, so the offset will vary according to that.
- But not many people will want an actual achieved temperature outside the range 215°C - 240°C (420°F - 464°F), so the offsets are going to be very similar at all these temps, not different enough to worry about checking the % each time.
As an aside, it's this over-heating of the coil - and thus under-setting of our target temp - that explains why it was common in the earlier days of TC to see YouTubers like Busardo talk about "this tank tastes burnt at more than 300°F, while this RDA needs 450°F". The joys of Ni200
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Okay, thanks for that.
As for the varying resistance thing. I guess I'm not sure what is causing it. It will usually change by about .01 to .02 after a few hours use on a brand new coil but after that it stays the same until I change the coil. I do use the lock resistance feature on my IPV3li though and that is when it changes (after going back to room temp of course) Usually Ill do it in the mornings when its been sitting all night but it only ever changes the first time after installing and using a new coil for a bit.
As for static resistance one thing I'm not clear on is that when your mod or ohm reader reads a resistance do the results shown include the static resistance or is the static resistance something that has to be calculated and counted into the read resistance?
Also, if I just adjust the temp to my preference through feel rather than just punching in the number when putting on a new atomizer or coil a little bit of static resistance isn't going to hurt much right? I guess its kind of moot until I see what the difference is in the morning with and without the heat sink.
As for the varying resistance thing. I guess I'm not sure what is causing it. It will usually change by about .01 to .02 after a few hours use on a brand new coil but after that it stays the same until I change the coil. I do use the lock resistance feature on my IPV3li though and that is when it changes (after going back to room temp of course) Usually Ill do it in the mornings when its been sitting all night but it only ever changes the first time after installing and using a new coil for a bit.
As for static resistance one thing I'm not clear on is that when your mod or ohm reader reads a resistance do the results shown include the static resistance or is the static resistance something that has to be calculated and counted into the read resistance?
Also, if I just adjust the temp to my preference through feel rather than just punching in the number when putting on a new atomizer or coil a little bit of static resistance isn't going to hurt much right? I guess its kind of moot until I see what the difference is in the morning with and without the heat sink.
@TheBloke: Great post!
A lot of cases: SR, +VR, -VR... In the end, isn't it all "the same" in a sense that
I think this should read: "So 0.02Ω SR will cause +52.50ºC inaccuracy with the 0.08Ω coil, and +7.0ºC with the 0.60Ω coil."
A lot of cases: SR, +VR, -VR... In the end, isn't it all "the same" in a sense that
- the temperature offset (up or down) is proportional to the amount of "unwanted" resistance (whether it stays, comes or goes)
- the temperature offset (up or down) is inversely proportional to the base resistance of the coil
- the TCR of the wire material doesn't matter at all (in any of these cases)
I think this should read: "So 0.02Ω SR will cause +52.50ºC inaccuracy with the 0.08Ω coil, and +7.0ºC with the 0.60Ω coil."
Another excellent evaluation and post as I really enjoy reading your careful analysis of the facts at hand.Here you go @BrentMydland - something I had been meaning to write about for a little while anyway.
TC Inaccuracy from Atomizer Resistance - Static and Variable
Static Resistance (SR)
SR = any amount of resistance read by the mod which is not accounted for by the wire in the coil itself, and which is always present (static)*.
Therefore it is primarily the resistance of the atomizer itself - its positive pin, its positive and negative block/posts, and any intermediate metal. The positive is usually the higher resistance, as the negative goes through the body of the atomizer which is much thicker and so lower resistance (though the positive is often partly brass or copper to balance this out.)
SR can possibly also include the wiring to the mod's 510 and the 510 itself, depending on whether this has been measured and automatically subtracted by the mod/chip maker. (Users of the DNA 200 can adjust this themselves via eScribe's Mod Resistance setting.)
The impact of static resistance (SR) depends entirely on the base resistance of the coil. It is irrespective of the TCR, and therefore also, technically, of the wire used.
However as the wires we use have different resistivity, in practice the wire used does impact the likely effect from SR. Ni200 coils are almost always very low resistance and thus experience high inaccuracy from SR, where Stainless Steel resistance is almost always much higher and therefore much lower inaccuracy, and so on. Titanium and NiFe are in between, with Titanium less affected than NiFe.
I consider 0.01Ω to be the maximum amount of static resistance I will willingly accept. Most of my tanks that I have checked are no more than 0.005Ω, but I haven't been particularly bothered to test them all quickly. I'll do it over time, as I feel like it, and I wouldn't stop using a nice tank if I did find it was more than 0.01Ω. I would though see if I could improve it. I have already improved a few tanks by replacing stainless parts with brass, in particular my Squape Rs clones. My best tanks for SR are my authentic Aqua v2s, which have an all-copper positive path that I measured as 0.0004Ω!
As mentioned, the inaccuracy caused by SR is relative to the base resistance of the coil. It is also relative to the target temperature - it is best expressed as a % of the target temperature.
Here's the inaccuracies caused by 0.01Ω of static resistance for the following coil base resistances as a % of the target temperature, and actual inaccuracy at target temperature = 230°C (446°F)
- 0.08Ω: +11.41% | +26.25°C
- 0.12Ω: +7.61% | +17.50°C
- 0.15Ω: +6.09% | +14.00°C
- 0.20Ω: +4.57% | +10.50°C
- 0.40Ω: +2.28% | +5.25°C
- 0.60Ω: +1.52% | +3.50°C
I have expressed the inaccuracies as + numbers, by which I mean they are the amount by which the mod will overheat the coil. So a 0.08Ω coil with 0.01Ω SR (read by the mod as 0.09Ω) set to 230°C will actually be heated to 256.25°C, which is +11.41% of the target temperature.
The percentages change linearly with SR. So 0.02Ω SR will cause +52.50% inaccuracy with the 0.08Ω coil, and +7.0% with the 0.60Ω coil. They also change linearly with decreasing base resistance - for example note 0.40Ω being half the inaccuracy of 0.20Ω.
As SR always leads to overheating the coil, the natural fix is to set our target temperature lower than we want to achieve. To compensate, we can simply set it lower on the mod by the amount indicated above - eg if we know we have 0.01Ω SR on a 0.20Ω coil, and our actual target temperature is 230°C, we set mod to 220°C. Rounding as appropriate to get the nearest °C or °F setting the mod will do.
* The exact definition of the 'static' in SR is: present at the time the cold base resistance of the coil is measured by the mod, and then present inthe same amount throughout all subsequent vapes until the next base resistance measurement.
If the resistance is not present during one or the other occasions, or its amount changes, then that (or some part of it at least) becomes Variable Resistance:
Varying Resistance (VR)
VR = any amount of non-coil resistance which comes and goes, for example caused by the atomizer not being screwed on as tightly as possible to the mod, or by screws not being tightly secured onto the coil, loose posts, or any other resistance that cannot be guaranteed at a single figure.
VR should be avoided wherever possible because it is unpredictable and thus cannot be easily compensated for.
VR affecting the base/cold coil resistance reading
Let's look at a 0.01Ω varying resistance that is there when the cold resistance is read, and then disappears later; perhaps the atomizer was not fully tightened at first and was then adjusted later.
VR of this nature - present for base resistance, gone later - should be removed over time on mods with Refinement: the DNA 40, DNA 200, and some clones of the DNA 40. It will detect the resistance has gone down, and adjust its base reading accordingly.
- Two examples, two different atomizers on two different identical mods
- The atomizers themselves have 0.01Ω SR
- Coil One is really 0.20Ω, but the SR + VR causes the mod to read it as 0.22Ω.
- Coil Two is really 0.40Ω, but the SR + VR causes the mod to read it as 0.42Ω.
- The user has a desired target temperature of 230°C
- Some vapes are taken before the VR disappears. There is 0.02Ω SR+VR in place, therefore the inaccuracies are:
- Coil One, 0.20Ω : +9.13% = +21.00°C = heated to 251°C on a 230°C setting
- Coil Two, 0.40Ω : +4.57% = +10.50°C = heated to 240.5°C on a 230°C setting
- These are just the same as if there had been 0.02Ω SR.
- Now the VR disappears, but the mod still thinks the base resistance is 0.42Ω
- Coil One, 0.20Ω : Will be heated to 265°C = an inaccuracy of +35°C
- Coil Two, 0.40Ω : Will be heated to 247°C = an inaccuracy of +17.5°C
- The fact that the VR has gone makes things a lot worse, an extra 50% inaccuracy compared to when it was there, because now the base resistance reading is out of sync with the in-vape resistance readings.
It will not be removed, and will cause ongoing inaccuracy, on "Set Resistance" chips such as the Yihi, Dicodes, etc - or on the DNA 40/200 if the "lock resistance" feature is used.
I do not recommend "lock resistance" is ever used on an Evolv chip, it's not the same as Set Resistance on a Yihi and all it does is hide underlying atomizer problems.
We could regard base readings taken on non-cold atomizers (eg moved from another mod and not cooled) as also being VR. Well in fact it is VR, just of a different cause to the mechanical components we normally associate with SR/VR.
VR not present during the base/cold coil resistance reading but then appearing during vapes
For this case, let's assume the base/cold coil resistance was read correctly but then 0.01Ω VR suddenly appears in the middle of a vape. For simplicity, this example assumes there's not also any SR:
A 0.20Ω coil, read correctly by the mod as 0.20Ω, but then exhibiting +0.01Ω VR during the vape, will have an inaccuracy of -14.3°C; it will be underheated, not overheated as in the SR cases.
This case would include situations where the atomizer was accidentally unscrewed a touch from the mod, or otherwise became slightly looser - causing the base reading of the coil to increase.
I am not yet sure if DNA Refinement helps correct this: it's much harder for the mod to detect, because it has to be sure that the rising resistance isn't just normal heating of the coil, but actually the base resistance rising. Maybe the DNA 40/200 does address this, perhaps by detecting base resistance rose for a long period during which no vaping occurred? I'm trying to test it now and will update.
Summary:
- Varying Resistance: if you've got it, check your atomizer/mod and fix it; it is, as the name suggests, variably impactful and there's no good reason to put up with it.
- It might underheat, it might overheat, and either way it will do much more damage than SR
- Static Resistance: every atomizer has some amount, and unless you're using Ni200 it's rarely a big deal
- It applies fairly minimally for most resistances you are likely to build to with Titanium, Stainless Steel, and (to a lesser extent) the NiFes.
- With NiFe70 single coil you might get down to 0.15Ω or so, and thus be subject to 6%, or around 14°C at common TC temps.
- NiFe52 single coil should not usually be worse than 4.5%, or 10°C at 230°C/450°F, and will often be better (my standard coil of NiFe52 will be 0.30Ω)
- SR maximums: I consider 0.01Ω to be a good guideline maximum: with at most this a mount of SR, at the resistances I build, I don't have to think about offsets.
- I set 235°C every time and my vapes are pretty consistent (on accurate mods) regardless of the atomizer in use
- If you've got more than 0.01Ω you can use the figures in this post to decide how bad it is at your usual base resistances and either try to reduce it, or just account for it in your target temperatures.
- Adjusting for SR: In all cases of high(er) SR, the result will always be that the mod over-heats the coil
- So it can be counteracted by lowering your target temperature by the amount indicated by the inaccuracy
- Remember that the inaccuracy is a % of the target temperature, so the offset will vary according to that.
- But not many people will want an actual achieved temperature outside the range 215°C - 240°C (420°F - 464°F), so the offsets are going to be very similar at all these temps, not different enough to worry about checking the % each time.
As an aside, it's this over-heating of the coil - and thus under-setting of our target temp - that explains why it was common in the earlier days of TC to see YouTubers like Busardo talk about "this tank tastes burnt at more than 300°F, while this RDA needs 450°F". The joys of Ni200
Just before reading your post I was looking at a very interesting atty and saying to myself how this atty would handle TC with the possible massive static resistance it might have. It is a very interesting and unique design but if it has too much static resistance than it is a bad choice for TC which is all I use for the last several months.
3 in 1 SKYFALL squonk RDTA from Focusecig
Mostly yes!
On 2 - Yes, the amount of offset that will be required is inversely proportional to base resistance of the coil: the lower the base resistance, the greater offset required.
On 1, yes the amount is proportional to the amount of unwanted resistance. But the direction (whether up or down offset) varies between SR and VR - all SR is a "down" offset (we reduce the temperature to compensate), VR can be either up or down.
I think it's worth also making the point that VR is different in effect, in particular that a certain case of VR can result in an underheat, where all cases of SR result in overheat.
This is one reason I separated out VR. All SR cases (extra resistance is present at all times, static) result in overheating the coil (so we lower the temperature to adjust). But in one VR case - that is where the variable resistance is not present in the base resistance reading, but then appears during normal vapes - will result in an underheat.
Another reason to separate out SR and VR is that we can see that SR is a) always present (to some degree) and b) not so bad. In many cases (with higher resistance coils) we can simply forget about it. Or if it is there in a higher amount, we can predictably adjust for it.
These things are not true for VR - it is unpredictable, it cannot be easily accounted for.
Therefore I think people should not tolerate varying resistance fluctuations in the same way they tolerate normal levels of constant static resistance. So I want them to be aware that VR is different to SR in practice, even if the numbers are proportionately the same.
Thanks! I wanted to use the % figures there but I put the °C figures in as %
It should read So 0.02Ω SR will cause +22.83% inaccuracy with the 0.08Ω coil, and +3.04% with the 0.60Ω coil.
I have edited.
I've removed that statement for now.
Firstly, I was wrong to say it's not the same as Yihi Set Resistance. Of course it mostly is the same. The difference being it's locking an automatically taken resistance reading rather than being manually taken, on-demand like on the Yihi. That might make things less convenient on the Evolv, if you lock resistance: If for example you accidentally lock/set a too-high resistance on a warm atomizer, on the Yihi you can simply set it again any time, whereas on the Evolv you cannot - at the least you have to unlock and then wait for refinement, or in practice remove the whole atomizer and re-do it.
But my main point was that locking resistance is preventing a useful feature of refinement, adjusting for natural resistance changes due to background temperature. The reason to do it - fluctuating resistance - is going to cause problems anyway, and locking the resistance seems like it really only hides or transfers that problem rather than encouraging the user to fix it.
But I've removed the whole thing because I need to think about it more and experiment. I think I am right to say that generally speaking lock resistance should not be needed, but I don't know if I'm right to say that there are big downsides in using it. So I will come back to that later
Titanium coils? Spaced or contact? When do you do your first Set Resistance, before or after wicking?
Included. The total resistance figure that the mod reads, and which it shows on its screen, is:
- CR + SR
- CR = Coil resistance
- SR = Static Resistance
You can often get an idea for how much SR there is by a) checking the resistance of a given build on a mod that shows resistance to three decimals (eg the IPV3Li), b) calculating from Steam Engine Wire Wizard the resistance for the stretch of wire you used for that coil - being very careful that you have the exact right width of wire, are correctly counting the number of wraps of the accurate inner diameter, and are including the right amount of leg length.
Or a more accurate way: Cut a short section of a higher resistance wire, like Kanthal or Stainless Steel. Attach it tightly between the posts of the atomizer - not coiled, just straight between them (or slightly bent if necessary depending on the deck layout.) Measure the resistance on an accurate mod with three decimal place display. Now remove the stretch of wire and precisely measure its length, using digital callipers if possible. Now use Wire Wizard to calculate the resistance of that length of wire - on Wire Wizard, enter 0 for wraps and 0 for inner diameter, then just put the length of the wire into the "Leg Length" box, like this:
Make sure the wire thickness is correct - you can see there how I didn't enter 26G, but entered 0.40mm as I know my wire is 0.40 not 26G exactly. Buying wire in the US it's more likely to be 26G (0.405mm), but some wire is given in metric so check.
Anyway, once you know the resistance of the exact amount of wire you used, just subtract that figure from the resistance value you got on the mod. Whatever's left is the static resistance of that atomizer.
When I do this, I get a nice flat, straight piece of wire, and then I tighten it down really hard, hard enough that the screws cause a distinct bend/distortion in the wire at the point where I attached them to the atomizer. Then I can much more easily measure the precise length between those indents, to see what figure to put into Wire Wizard
Yeah, adjusting to taste is absolutely fine. Whatever gives you a vape you like is fine! TC doesn't need to be ultra accurate, any TC vape that feels good and doesn't give dry hits is a fine TC vape.
Personally I like the idea that I can set any build on any atomizer on any (accurate) mod to 230°C and get the same vape. But it's no big deal at all if I can't.
For me, explaining this stuff is a) to show the underlying principles, so each person can take as much or as little from it as they want - and especially so they can handle the more extreme cases (like if someone currently only gets a good vape at 350°F and doesn't understand why) and b) for the interest of learning about and discussing the principles, for the general sake of knowledge and enjoyment - not necessarily for actual practical benefits.
So don't feel you have to make adjustments just because your vape is 12.71°C inaccurate
Enjoy the vape you want, that's all that matters.That's certainly an important point: while static resistance usually can be compensated, varying resistance can make TC unusable. However, both are undesired, and what we can do about it is:
- take care of good contacts (usually the cause for VR)
- choose higher resistance wire (to lower the impact of both SR and VR)
And finally: though it's tempting to expect a higher TCR would be a good thing with respect to SR/VR - it won't help.
I haven't watched the whole video, just scanned a bit, but I can't immediately see where the massive SR must come? The deck looks pretty normal? I scanned as far as him coiling/dry burning it and it still looked normal?
But let's say it does have massive SR - that's OK! As long as you know it's there and don't mind offsets, and as long as it is SR and not VR.
Let's say it had a vast amount, relatively speaking: 0.1Ω. That would mean that to achieve 230°C / 446°F on a 0.40Ω coil, you would need to set the mod to 173°C / 345°F.
After that it should theoretically be perfectly accurate. It's very similar in principle to vaping a Titanium coil on an Ni200 mod - the temperature range is offset quite considerably, but it still works.
There's nothing wrong with that per se. It would be nice in a perfect world if 230°C/450°F was 230°C/450°F everywhere and always. But ultimately all that matters is the good vape.
So don't discount this tank even if it has loads of SR. As long as it's only SR, not VR, you can adjust for it. Then it's up to you to decide if the benefits of the tank are worth the fact that you need to remember to set the temp 10, 50, 100 or 150°F lower, whatever it might be. Personally I'd happily do that if the tank offered something special. I already do that all the time: I have Titanium on Ni200-only mods, I have mods that under-heat every coil, I might soon even have SS coils on Titanium mods. I'm a long way from 230=230=230!
I like the idea in principle, but I'm not going to retire my Ni200-only mods because they need offsets, and I wouldn't ignore an otherwise great/special tank because it also needed offsets.My recommendation is to understand SR and see where you might have it, and if you can eliminate it great. Definitely eliminate VR. But if SR is there and can't be eliminated, then adjust for it and carry on.
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Vape Mesh company (one of their names ) refunded my order finally after a week of waiting .
This ended well considering that I would get a useless wire instead of NiFe70 which I ordered.
Now lets hope Stealthvape gets the NiFe70 soon and even better zivipf gets the NiFe52.
My Stealthvape Ti should be here tomorrow so at least I will experiment on that.
Can't wait to try more TC wires, I decided that Dicodes Resistherm is not for me at least in that diameter and I am definitely not going back to NI200...
This ended well considering that I would get a useless wire instead of NiFe70 which I ordered.
Now lets hope Stealthvape gets the NiFe70 soon and even better zivipf gets the NiFe52.
My Stealthvape Ti should be here tomorrow so at least I will experiment on that.
Can't wait to try more TC wires, I decided that Dicodes Resistherm is not for me at least in that diameter and I am definitely not going back to NI200...
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