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

[TheBloke]

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!

Yes NiFe52 is the winner. NiFe70 is still going to be a great wire, and we should remember that the differences in theoretical accuracy between 52 and 70 are not necessarily going to be noticeable in day to day vapes.

So it will be interesting to see, once both 52 and 70 are available in vape size spools, which is the day-to-day winner. It may well come down to things like whether the wire is annealed or not (Stealth Vape's NiFe70 will be annealed, the other NiFe70s and the NiFe52 may not be), thus how strong it is, how springy it is, and that sort of thing.

All that remains to be tested, which I will definitely be doing.

I am getting my first proper gauges of NiFe wire (ie thicker than 30 and 29 gauge!) early next week, from Crazy Wire. That will be awesome because it will be the first time I've had a NiFe wire in a proper size, that I didn't feel like I had to twist to get a decent surface area. And therefore first time I will be able to do a like-for-like comparison with Titanium using my preferred 26G wire.

Then 7-14 days after that, NiFe52 will be available also in decent sizes (30 - 26G) from Thomas @ ZiVipf, and I will get that as soon as he can send it to me, and of course tell you guys so you can order it as well.

That will be the theoretical most accurate wire, and it's higher resistance will somewhat reduce power/battery requirements, and may enable a slightly wider range of building. But NiFe70's resistance is not so low as to inhibit building, I expect; it's not low like Ni200 is low.

As for the offsets required in Ni200 or Titanium mode: NiFe52 @ 0.004 will be more like 150-160 on Yihi I think. For the dna 40 you can find out easily and immediately, because @Dampmaskin has implemented his "Ni200 equivalence chart" on his Wire Wizard. Choose the wire you will vape on - eg Kanthal Nifethal 52 - then choose Ni200 equivalence. That will show you the setting on a DNA 40 mod for the real temperature. It's called Ni200 Equivalence but it should really be callled DNA 40 Equivalence, because it assumes the real curve of Ni200 which in practice only the DNA 40 has implemented. On a Yihi, and pretty much every other TC mod out there, you need lower figures - eg the 150-160 on the Yihi we just mentioned. But for a DNA 40 it's a useful chart. I've put in a feature request to Lars to ask him to note that it's only appropriate for the DNA 40 to avoid confusion.

As soon as I get my NiFes in 26G I will be doing some real temp testing to come up with the exact numbers to use on mods like the Yihi, in both Ni200 and Titanium modes.

 

[TheBloke]

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!

Great stuff! That is exactly why I love NiFe wire, because it has all those advantages and it's more accurate than SS.

Although what the last few days have taught me is that actually SS is not nearly as inaccurate as I thought - in fact it may even be more accurate than Ni200!

So I won't try and move you away from your new SS onto yet another wire I will be doing some real temp testing with SS wire ASAP to check the theoretical results work in practice.

In the meantime, glad you're back on a wire you like!

 

[yo han]

Ooooh well, now we want to know everything about your wire, build and settings.

Nothing special cigatron; just 8 wraps of 28 awg UD 316L wire (3mm diameter) on my Subtank Mini RBA. It was just a quick job but it works 10 times better than messing around with nickel or titanium. Nickel is too soft and titanium too springy in my opinion. Stainless steel just stays where it is (unlike titanium) and doesn't get messed up when pulling cotton through (like nickel). Love it!

 

[yo han]

Great stuff! That is exactly why I love NiFe wire, because it has all those advantages and it's more accurate than SS.
Although what the last few days have taught me is that actually SS is not nearly as inaccurate as I thought - in fact it may even be more accurate than Ni200!
So I won't try and move you away from your new SS onto yet another wire I will be doing some real temp testing with SS wire ASAP to check the theoretical results work in practice.
In the meantime, glad you're back on a wire you like!

Thanks for trying the things none of us (or at least not many) have yet tried Bloke!
Your experience with SS made me want it and it's just like you said. Too bad hardly any device has a setting for it but it's working great on my SXK Flask. Glad I bought this thing!

 

[TheBloke]

Thanks for trying the things none of us (or at least not many) have yet tried Bloke!
Your experience with SS made me want it and it's just like you said. Too bad hardly any device has a setting for it but it's working great on my SXK Flask. Glad I bought this thing!

Thanks! It really is a pleasure.

The number of TCR mods is growing quite well now. DNA 200 of course, available in lots of different mods now and soon. The new Smok chips, XCube 2 and Koopor Mini (and Treebox, probably identical to Koopor.) Of those, only the XCube 2 currently allows TCR to go down to SS level, and I haven't yet tested it (SS came only in the most recent FW update.) There's a chance they'll add SS to the Koopor as well.

Then the new Apollo Reliant 60w, which is in fact the SXK++. It's the SXK chip at heart, big screen version, hence having the same 10 -100 TCR scale which still requires an offset (eg 40 instead of 35 for Titanium).

But it has a number of great improvements, such as in TC mode the temperature is now on the up/down buttons, rather than buried in a lock-mode menu. And for swapping between TC and VW, rather than the ridiculous Evolv system of turning temp to off, then back to the temp you want to go back to TC, it now has a proper mode selector: Hold + and Fire for a couple of seconds and you get a menu, where up/down scrolls through Temp, Wattage, and Mech (a new mode added, no interest to us really.) The ability to switch easily from VW to TC and back again is a great feature for any dry-burnable TC wire such as SS and NiFe.

The Apollo Reliant 60W really seems like the SXK v2 or even v3 - it's the same core but with a whole bunch of good improvements, lots of cleaned up annoyances, a nicer UI, and is now being properly marketed as a TCR mod rather than 'nickel purity'. Another small but nice example: It doesn't flash Temperature Protection, blocking your screen. It instead shows the letters 'TP' in the middle. So it still shows you when TP has kicked in, but doesn't block any information.

So if you're looking for another SS mod, that's a natural one to look at. £80 list price in the UK, but there was a discount code taking it down to £60.

Then there's also the upcoming new SXK own-brand mod, the SXK Mini Zero. That's another big screen mod, will be available from end Sept at $50 from China, and it will be interesting to see how many of the improvements I described above it has. In other words, how much of what I've seen on the Apollo came from Apollo themselves, versus SXK. Or at least, how much of the Apollo-SXK partnership SXK have been able to release in their own mod.

 

[Mad Scientist]

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.

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 0.40Ω Titanium coil and a 0.50Ω SS coil. Whatever coil type is chosen as the comparison, Ni200 will be roughly 4x lower resistance than Titanium but only have 1.5 to 2x the TCR, and five 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 properties that make it highly accurate, but these are not applying 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 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 been done already. 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 SR in the atomizers. But as all they need to do is detect the difference between "normal vape" and "dry hit", it does sort of work. Quite impressive.

Hi Bloke,

When discussing accuracy, I'm guessing you calculated a minimum dynamic resistance for acceptable accuracy. This is why you disfavor Ni 200.

What did you come up with for that minimum resistance? I try to keep all my builds at 0.1 and above with most at least approaching if not exceeding 0.2 (Ti G1). Is there a sweeter sweet spot? Thanks.

 

[TheBloke]

Hi Bloke,

When discussing accuracy, I'm guessing you calculated a minimum dynamic resistance for acceptable accuracy. This is why you disfavor Ni 200.

What did you come up with for that minimum resistance? I try to keep all my builds at 0.1 and above with most at least approaching if not exceeding 0.2 (Ti G1). Is there a sweeter sweet spot? Thanks.

When comparing accuracy, I did it the other way around. I didn't look at resistance first, I looked at the coil I wanted to build.

My default build is 8 x 3mm wraps of 26G, slightly spaced . This build:

• Fits in all my atomizers, including cramped dual-coil decks with narrow chimneys
• Provides, I feel, enough surface area for good flavour and adequate vapour
• Is just what I'm used to building.

So I then compared the base resistance of the various materials using that reference coil:

• Ni200: 0.077Ω
• NiFe70: 0.16Ω
  
• NiFe52: 0.296Ω
• Titanium: 0.376Ω
• SS 304: 0.571Ω

I then ran the numbers on accuracy, using a single static TCR (averaged for the vaping range up to 250°C), which I divided into the stated milli-ohm accuracy of the best TC mods (DNA 200, Dicodes, Yihi SXM), to give me a "accurate to nearest X°C" figure.

Actually, I have so far only run those numbers for two wires, which you probably saw in my post yesterday comparing NiFe52 and NiFe70.

I have plans to run all the numbers for all the wires for a Wire Comparison Chart. For that I expect I will do two builds, the one above and then maybe one more, 28G or something.

I discussed making such a table with @vapealone , and he turned it into something more generic - a Temperature Sensitivity chart. He used the general numbers to work out how sensitive each material was, using Ni200 as the base (as it turns out it's the worst.) That is basically doing the same thing I do above, but instead of giving us absolute accuracy numbers, it gives us a relative comparison between the wires.

It showed that Titanium was roughly 4x as sensitive/accurate as Ni200, NiFe52 was I think around 3x as sensitive/accurate, and so on. And it also showed us that this varies across the vaping temperature range, because of curves in the TFRs - Ni200 being the one that curves most. But Ni200 was always at the bottom.

So to answer your question, no I didn't measure a minimum acceptable resistance. Rather I prefer the other way around - I don't want my wire to dictate to me what build I make. I want to choose a build, and then see how accurate it is.

The good thing is that, as long as you're not using Ni200, you almost certainly don't need to vary your build. Choose Titanum, choose a NiFe, even it seems choose a Stainless Steel, and then build what you want. Yes if you build higher resistance it will be more accurate, but probably not so significantly.

But if we do need a rule of thumb, it's just that "the higher the resistance the more accurate".

As for your 0.20Ω Titanium build, it's accurate to nearest 1.42°C. Every milli-ohm of resistance equals 1.42°C of temperature change. If you built to 0.40 instead, it'd be twice as accurate, to nearest 0.71°C.

In my view once we're in the range of nearest-2°C and below, no-one is going to able to tell the difference between any further variances.

The final point is SR, which we know is irrespective of TCR. At 0.20Ω, each 0.001Ω of SR equates to 1.1°C inaccuracy. 0.01Ω would be 11°C. At 0.40Ω, that's halved to 5.5°C. Neither seems to me too terrible.

How much does that matter in real life? Depends on your atomizers of course, and I am now trying to reduce SR everywhere I can (replacing some stainless pins with brass for example.) But in truth, I think probably "not a huge amount". I'm sure you're using good quality atomizers and therefore 0.01Ω is a reasonable maximum SR to expect in day to day vaping.

Therefore 5°C or 10°C here or there is not that significant I believe. I set any new build to 230°C (450°F) and it usually vapes great. Where I have to adjust it's usually on my cheaper clone mods, which are anyway using offsets because they're Ni200 only.

Of course things will be very different on a 10-milli-ohm accurate mod - if such a thing exists; maybe all mods use three decimals internally despite many only displaying two on screen. Anyway, if the do only have 10-mΩ accuracy, then that 1.42°C because 14.2°C increments, and now it would be noticeably more accurate building Titanium to 0.40Ω versus 0.20Ω. But if you're using only the DNA 200, Yihi chips, Dicodes etc, you don't even need to think about that.

TLDR: I recommend building the coils you want, and working out accuracy afterwards. As long as you're not using Ni200, I don't think you need to greatly change your build. Higher resistance is always better, so certainly don't artificially reduce resistance. But if your ideal Titanium coil is 0.20Ω, build 0.20Ω - you're getting a very accurate TC vape.

 

[Mad Scientist]

When comparing accuracy, I did it the other way around. I didn't look at resistance first, I looked at the coil I wanted to build.

My default build is 8 x 3mm wraps of 26G, slightly spaced . This build:

• Fits in all my atomizers, including cramped dual-coil decks with narrow chimneys
• Provides, I feel, enough surface area for good flavour and adequate vapour
• Is just what I'm used to building.

So I then compared the base resistance of the various materials using that reference coil:

• Ni200: 0.077Ω
• NiFe70: 0.16Ω
  
• NiFe52: 0.296Ω
• Titanium: 0.376Ω
• SS 304: 0.571Ω

I then ran the numbers on accuracy, using a single static TCR (averaged for the vaping range up to 250°C), which I divided into the stated milli-ohm accuracy of the best TC mods (DNA 200, Dicodes, Yihi SXM), to give me a "accurate to nearest X°C" figure.

Actually, I have so far only run those numbers for two wires, which you probably saw in my post yesterday comparing NiFe52 and NiFe70.

I have plans to run all the numbers for all the wires for a Wire Comparison Chart. For that I expect I will do two builds, the one above and then maybe one more, 28G or something.

I discussed making such a table with @vapealone , and he turned it into something more generic - a Temperature Sensitivity chart. He used the general numbers to work out how sensitive each material was, using Ni200 as the base (as it turns out it's the worst.) That is basically doing the same thing I do above, but instead of giving us absolute accuracy numbers, it gives us a relative comparison between the wires.

It showed that Titanium was roughly 4x as sensitive/accurate as Ni200, NiFe52 was I think around 3x as sensitive/accurate, and so on. And it also showed us that this varies across the vaping temperature range, because of curves in the TFRs - Ni200 being the one that curves most. But Ni200 was always at the bottom.

So to answer your question, no I didn't measure a minimum acceptable resistance. Rather I prefer the other way around - I don't want my wire to dictate to me what build I make. I want to choose a build, and then see how accurate it is.

The good thing is that, as long as you're not using Ni200, you almost certainly don't need to vary your build. Choose Titanum, choose a NiFe, even it seems choose a Stainless Steel, and then build what you want. Yes if you build higher resistance it will be more accurate, but probably not so significantly.

But if we do need a rule of thumb, it's just that "the higher the resistance the more accurate".

As for your 0.20Ω Titanium build, it's accurate to nearest 1.42°C. Every milli-ohm of resistance equals 1.42°C of temperature change. If you built to 0.40 instead, it'd be twice as accurate, to nearest 0.71°C.

In my view once we're in the range of nearest-2°C and below, no-one is going to able to tell the difference between any further variances.

The final point is SR, which we know is irrespective of TCR. At 0.20Ω, each 0.001Ω of SR equates to 1.1°C inaccuracy. 0.01Ω would be 11°C. At 0.40Ω, that's halved to 5.5°C. Neither seems to me too terrible.

How much does that matter in real life? Depends on your atomizers of course, and I am now trying to reduce SR everywhere I can (replacing some stainless pins with brass for example.) But in truth, I think probably "not a huge amount". I'm sure you're using good quality atomizers and therefore 0.01Ω is a reasonable maximum SR to expect in day to day vaping.

Therefore 5°C or 10°C here or there is not that significant I believe. I set any new build to 230°C (450°F) and it usually vapes great. Where I have to adjust it's usually on my cheaper clone mods, which are anyway using offsets because they're Ni200 only.

Of course things will be very different on a 10-milli-ohm accurate mod - if such a thing exists; maybe all mods use three decimals internally despite many only displaying two on screen. Anyway, if the do only have 10-mΩ accuracy, then that 1.42°C because 14.2°C increments, and now it would be noticeably more accurate building Titanium to 0.40Ω versus 0.20Ω. But if you're using only the DNA 200, Yihi chips, Dicodes etc, you don't even need to think about that.

TLDR: I recommend building the coils you want, and working out accuracy afterwards. As long as you're not using Ni200, I don't think you need to greatly change your build. Higher resistance is always better, so certainly don't artificially reduce resistance. But if your ideal Titanium coil is 0.20Ω, build 0.20Ω - you're getting a very accurate TC vape.

Sounds good. Thanks!

 

[dwcraig1]

I guess I'm going to have to just suffer through it providing my FT Ti is any good, it's almost here. Cleared Customs yesterday, 150 feet will last me awhile. But you guys can still send me all your "70" after you get the "52"

 

[TheBloke]

I guess I'm going to have to just suffer through it providing my FT Ti is any good, it's almost here. Cleared Customs yesterday, 150 feet will last me awhile. But you guys can still send me all your "70" after you get the "52"

Yes I'm going to be getting more NiFe in the coming weeks than I can ever expect to use, so I will certainly PIF

But anyway, Titanium is more than fine

The differences of, say, NiFe52 compared to Titanium is perhaps the difference between a Mercedes and a Ford.

Whereas Titanium to Ni200 is a Ford to..

 

[TheBloke]

I am of course exaggerating

On a hypothetical desert island with only Ni200 and Kanthal, I'd use the Ni200 versus going back to non-TC Kanthal. I'd definitely grumble about it all the time though.

 

[tchavei]

I resent the Mercedes comparison. Ti is the Mercedes. Might not be the best, but it has a name and "titanium" is a name way older than NiFe [emoji14]

Regards
Tony

Sent from my keyboard through my phone or something like that.

 

[TheBloke]

All right then the Titanium is the Mercedes and NiFe52 is a Pagani Huayra

 

[cigatron]

Nothing special cigatron; just 8 wraps of 28 awg UD 316L wire (3mm diameter) on my Subtank Mini RBA. It was just a quick job but it works 10 times better than messing around with nickel or titanium. Nickel is too soft and titanium too springy in my opinion. Stainless steel just stays where it is (unlike titanium) and doesn't get messed up when pulling cotton through (like nickel). Love it!

Wow, SE shows that build to be close to 1ohm.

 

[TheBloke]

Wow, SE shows that build to be close to 1ohm.

That's good - maximising the accuracy, doubly important with SS!

It does raise a good point though, one we've briefly touched upon before: do any mods have upper limits on the ohms? The specs claim they do, but we found that to be mostly wrong.

We know for sure the DNA 40 has no hard limits - it soft limits as necessary if the ohms would take it over its volt limit.

Other devices we can't assume anything.

But with SS it's no big deal, because the TCR is low enough that the resistance will, relatively speaking, barely rise. That 1.0Ω SS coil will rise to 1.21Ω at 230°C/450°F.

It might only become an issue if one did, say, a 1.5Ω - 2.0Ω coil of Titanium or a NiFe, which might then rise up to or even over 3.0Ω which would definitely soft limit and might hit hard limits on some mods.

But in general, higher = better, certainly up to 1.0Ω cold resistance or so.

 

[cigatron]

My Evic specs upper limit in tc at 1 ohm. Others have had it jump out of tc when exceeding 1 ohm. I never have, I'm running Ti at .2 ohms. I know, I know, I should be running it at .4 for better accuracy...lol, just don't have the 28g on hand.

Edit: Wait, I do have 30g Ti-G1. Maybe I'll twist some up. That should get me pretty close to .4 ohms. I've always been a fan of kanthal. Hmmmm.

 

[TheBloke]

My Evic specs upper limit in tc at 1 ohm. Others have had it jump out of tc when exceeding 1 ohm. I never have, I'm running Ti at .2 ohms. I know, I know, I should be running it at .4 for better accuracy...lol, just don't have the 28g on hand.

OK interesting. Specs I've tested on other mods were wrong, but sounds like that one is real.

So unfortunately they actually put a hard limit in. They probably thought that >1.0Ω had to be Kanthal, so they would help users out by auto switching on an ohm-plus coil because they must have made a mistake.

With Ni200 that's a fair assessment. With Titanium it's usually going to be correct, but shouldn't be assumed. With SS it's plain wrong, but the Evic doesn't do SS so that's OK.

I always build Titanium to around 0.40, 0.50 as a max. I can't imagine myself ever going much above 0.5, let alone up to 1.0Ω, because I don't like thin wire and I can't fit a dozen or more wraps in (not that I'd want them anyway, as I exclusively use RTAs now and they don't have wide enough air holes.)

As I said to Mad Scientist, 0.20Ω Titanium is plenty accurate One of the many benefits of not using Ni200 any more is we don't have to be a slave to our builds. Build the coil you want, for the atomizers/decks you have and the vape properties you want. With Titanium, any build you make is going to be more than accurate enough - and more accurate than you had with Ni200.

Out of interest, what gauge and coil size are you using that comes out to 0.2? 24G? I do have two 24G Titanium coils running right now, which come to 0.25Ω - 0.28Ω

 

[cigatron]

Out of interest, what gauge and coil size are you using that comes out to 0.2? 24G? I do have two 24G Titanium coils running right now, which come to 0.25Ω - 0.28Ω

24g Ti-G1 from unkamen. 7/6 wrap, 2.8mm id, .4mm spaced coil wound on a machine screw. It's the longest coil I can comfortably fit on a STmini rba deck, which btw has about .01 ohm SR.

I have some 30g. I'll twisted some up and build a .4 ohm coil. It has about the same heat flux as the 24g.

 

[dwcraig1]

BTW, I'm a Ford man

 

[cigatron]

BTW, I'm a Ford man

I like the scooter.