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

[TheBloke]

Yeah I had the same thought - especially about customs!

Oh you're in the UK! I didn't realise that before. I might take a VF off you. Are they all the same colour, if so which?

 

[TheBloke]

Tom can you post a pic of the 510 on the SXK flask so I can see how wide the centre pin is?!?!

 

[TheBloke]

That's one I already had. Let me know if you need it clearer/different angle. Or I could just measure it, hang on

 

[Quantum Mech]

Yeah I had the same thought - especially about customs!

Oh you're in the UK! I didn't realise that before. I might take a VF off you. Are they all the same colour, if so which?

Ordered both black & silver VF
& just black VS [not sure if they did any other colour] as thought the VS looks best in black

 

[TheBloke]

The digital 300mm calipers I paid nearly £30 for from Amazon don't actually work as digital, they never turn on. But using it as a manual/analogue scale I would say it's 4mm diameter - definitely no less than 3.5mm, no more than 4mm, and 4mm is my best guess as far as I can judge it (the caliper arms don't fit right down into the 510 so I'm hovering above the pin a bit.)

 

[TheotherSteveS]

The digital 300mm calipers I paid nearly £30 for from Amazon don't actually work as digital, they never turn on. But using it as a manual/analogue scale I would say it's 4mm diameter - definitely no less than 3.5mm, no more than 4mm, and 4mm is my best guess as far as I can judge it (the caliper arms don't fit right down into the 510 so I'm hovering above the pin a bit.)

cheers mate. My best gues is a bit over 4mm edging toward 5 for the VS. I only have my toodlepuff protank 3 with me but the whole 510 is 5 mm across. I reckon the issue with the subtank is what i said - if the brass centrepin is flush or recessed on the atty, it wont connect properly or intermittently...well that fellates beasts of burden...

 

[Quantum Mech]

cheers mate. My best gues is a bit over 4mm edging toward 5 for the VS. I only have my toodlepuff protank 3 with me but the whole 510 is 5 mm across. I reckon the issue with the subtank is what i said - if the brass centrepin is flush or recessed on the atty, it wont connect properly or intermittently...well that fellates beasts of burden...

Just checked all my STM's & the centre pin sits slightly proud of the 510
I always seat the deck with the base in hand so don't know if that makes a difference to having the base on a device when seating the deck

 

[TheotherSteveS]

Just checked all my STM's & the centre pin sits slightly proud of the 510
I always seat the deck with the base in hand so don't know if that makes a difference to having the base on a device when seating the deck

Ok. Maybe try seating the deck first and really screwing it on (I know that makes it a bith to get the chimney ring off...). Then try again..

ps. we are kind of hijacking this thread a bit...

 

[KenD]

I hope its not a 510 issue as I was going to use this as a TC beater with with mini's and nano's!!

My Fogger v4 works fine, so thus far it seems more like an issue of my Subtank and VS not wanting to cooperate. Could be a problem if you need to use your Subtanks, but lets hope for the best.

 

[TheBloke]

It's fine, it's all related to the new SXK mods who don't have their own generic thread.

Anyway it's cool with me, every thread goes in and out of OT stuff and if it keeps it near the top of the forum it's all good to me

 

[TheotherSteveS]

My Fogger v4 works fine, so thus far it seems more like an issue of my Subtank and VS not wanting to cooperate. Could be a problem if you need to use your Subtanks, but lets hope for the best.

I will try to get one of my myriad ST minis/nanos on this beast asap and post. I just resurrected my earlier thread about VS clones so I'll probably post it there to leave this thread to get back OT!

 

[KenD]

just looking at it, the 510 brass pin is quite wide. If the brass/silverplate pin on the subtank is not standing above the 510 thread, it wont make contact...The fact that it works fine with the RDA suggests that this might be the case!

I tried two Subtanks, both with RBA decks. One worked, the other didn't. Strangely enough, I got the second subtank working both with an OCC head and a different rba head, so the problem seems to lie between the Subtank base and one of the rbas. But, even stranger, the Subtank and rba combination that didn't work on the VS works fine on my other mods. Need to investigate some more.

 

[KenD]

All SXK mods thus far appear to read resistance lower than most other mods. I'm in the process of calculating how much of a problem this is, when it is a problem - in some cases it could actually be ideal, because it counteracts static resistance.

But yes you should expect to see resistance readings of 0.03 - 0.04 lower than other mods under normal conditions.

Cotton burning at 70NP is not normal, that's a connectivity issue.

I was hoping I could build lower resistance coils so I could use some of my small deck dual coil RTAs, so the SXK reading too low sucks for me. Still, forced me to finally order some titanium wire so I guess that's good.

 

[TheotherSteveS]

I tried two Subtanks, both with RBA decks. One worked, the other didn't. Strangely enough, I got the second subtank working both with an OCC head and a different rba head, so the problem seems to lie between the Subtank base and one of the rbas. But, even stranger, the Subtank and rba combination that didn't work on the VS works fine on my other mods. Need to investigate some more.

Ok. It is a ST issue then most likely. I have had all sorts of problems with the OCC coils anyway but the RBAs have been fine so far!

 

[TheBloke]

I was hoping I could build lower resistance coils so I could use some of my small deck dual coil RTAs, so the SXK reading too low sucks for me. Still, forced me to finally order some titanium wire so I guess that's good.

Yeah. Well it fires down to 0.06 where previous DNA40 devices are 0.10 so depending on the exact offset you should be able to go a little lower at least. I'm calculating the exact offsets and the implications. Quite possibly something we can do further.

But yeah, moving away from Ni200 is a better thing anyway - Titanium, Stainless Steel, maybe Resistherm (though it's likely too expensive at the moment to be of huge interest to most.)

 

[ndb70]

Hi guys,
after an afternoon of experiments and formulas, I have some good and bad news...
The good first: using the calculated "corrected" TCReff with my dani, greatly improved the temperature displayed during the water test (constantly hovering around 94-96 °C)
The bad now: In my first study of the formula to find a TCReff, I'm ashamed to admit I screwed up and it is actually impossible to calculate a TCReff that doesn't depend on temperature.
I'll try to explain: you can only calculate a TCReff that will make temperature measurement accurate at a certain temperature, and you have to adapt your TCReff depending on the temperature you're interested in.
Ok, doesn't sound much clearer, let's try with some math, it's simple I promise, and someone can also double check I'm not screwing it up again...

My reasoning is, for a certain dT (i.e. the delta-T, i.e. the temperature difference between the calibration temperature T0 and the final temperature T), in an ideal world where all resistance is temperature dependent (i.e. non static resistance Kr), given a base resistance R0 at T0, we have

R(T) = R0 (1 + TCR * dT)

When Kr enters the scene, what we actually have is

R(T) = Kr + R0(1 + TCR * dT)

NOTE: for Ni200, TCR here is 0.62/100, i.e. a relative change of 62% every 100°C

Now, what we can do is find an TCReff such that

R0(1 + TCR*dT) = Kr + R0(1 + TCReff*dT)

But unfortunately, if you don't screw up this simple equation as I did in my first analysis, what you get is

TCReff = TCR - Kr/(R0 * dT)

That means that the best you can do is, say you're going to vape at 220 °C (i.e. dT ~= 200 °C), calculate a TCReff that will let the temperature accurate around 220 °C.

That is what I did with my water test.
I built a coil which steam-engine estimated being around 0.14 ohms, when on the characterized K4, my dani is measuring 0.16 ohm (which is quite OK with my findings of Kr ~= 0.026).
Now, if I do the water test with the nominal TCR of 0.62/100, my temperature hovers at around 78 °C.
So, since I want the measurement to be accurate at about 100 °C (i.e. dT = 80°C) I, calculated

TCReff = 0,62 - (0.02 * 100)/(0.14 * 80) = 0,441

So I dialed in 441 on the dani, waited for everything to cool down and repeated the water test, and now temperature stayed pretty much constant (while there was water on the wick) at about 95%.

So, the concept of a TCReff is still something that can give some more accuracy, but unfortunately I'm not sure it's as useful as I initially (and mistakenly) advertised as now you have kind of "plan for" which temperature you want your measurement work better...

Sorry again for misleading you with my mistake in my first post, which I apparently cannot edit anymore to put a warning at the beginning...

 

[balazsk]

All SXK mods thus far appear to read resistance lower than most other mods. I'm in the process of calculating how much of a problem this is, when it is a problem - in some cases it could actually be ideal, because it counteracts static resistance.

But yes you should expect to see resistance readings of 0.03 - 0.04 lower than other mods under normal conditions.

I have done a measurement by a calibrated MilliOhm meter.
SXK chip: 0.92Ohm
Ohm meter: 1.08Ohm
So the difference is 160mOhm what isn't really negligible.
I will do another measurement tomorrow with another coil to check whether the difference is constant or depends on the resistance.

 

[TheBloke]

I have done a measurement by a calibrated MilliOhm meter.
SXK chip: 0.92Ohm
Ohm meter: 1.08Ohm
So the difference is 160mOhm what isn't really negligible.
I will do another measurement tomorrow with another coil to check whether the difference is constant or depends on the resistance.

Yeah that level is very non-trivial. But it's also way, way higher than anything I've seen. Of course I am not comparing to accurate meter (yet), only to other mods. But I see 0.03-0.05 at worst across a range of resistances up to 0.60 as highest. I haven't tested any 1+ ohm coils yet.

It would be great if you could do as many tests as you can with your accurate equipment. I am in the process of trying to get a setup I can use with my DMM as well. And also running some tests to compare pure wire resistance versus atty resistance.

 

[TheBloke]

In other news, I'm vaping on a new SS317L contact coil, and it's great.

This time I pre-pulsed it until it turned quickly yellow then blue; yes - I was surprised! At first I thought I had put Titanium in by mistake! But I tested multiple times and repeated it each time (as long as I didn't heat the coil for too long - it starts glowing red hot faster than Titanium does.)

Maybe that's not unexpected for those in the know (@druckle ?), but I had no idea SS would turn yellow then blue just like Titanium.

Pulsing was done the same way I do Titanium:

• Wire: 150mm of SS317L 0.45mm / 25G, resistance around 0.76Ω
• Attached to an RDA on a random mod set to VW @ 30W (power, not TC.)
• I timed the pulse as 5 seconds to turn it partly blue - I tested this on three stretches of wire.
• On the piece below I then did a second 5 second pulse (once it had cooled down) to even the blue out across the wire.

It was super easy to coil a nice stable contact coil (helps that it's 25G):



I thought that might be sufficient oxidising for contact, but it wasn't. When trying the coil I had the same as I've seen on my previous SS contact coils: I need a couple of pulses as a contact coil before the resistance starts rising as normal for TC:

• First pulse it seems to get no resistance rise at all, the temp reading on the mod stays at 77°F like it does with Kanthal. This is effectively like a second dry pulse, because it's not limiting temp at all.
  • Stopped this uncontrolled pulse after a few secs, then:
• Second pulse is the opposite, resistance rises dramatically such that it quickly says it's at 700°F or something silly.
  • So it cuts power completely of course.
• Third pulse onwards, works fine as expected.

I am assuming that these are the symptoms of a coil that starts out shorting but then oxidises to fix those shorts.

During those dry burns I also saw inconsisent glowing across the coil, similar to what we see with Kanthal (part hot, part not.)

I did not have to tweak/move the coil at all to get it working normally after that - just two pulses then worked from the third.

I'm now vaping it in my Aqua SE RTA, NP set to 11 (tried @balazsk 's setting) and temperature at 350°F. So I'm still using an offset - I tried 380 to start with and it got a little dry towards the end of a long hit. 350 with 11NP is working great.

I just drained the tank empty and the Rayon completely white, and it TP'd as expceted. No dry hits, but a nice cloudy/flavourful vape before that point.

 

[TheBloke]

I should add that I have no reason to think that the blue pre-pulse is of any particular benefit. I did it thinking that this would pre-oxidise it, enabling contact coils like with Titanium. It did not.

I don't think it particularly made it much easier to work with either, again like it would for Titanium - SS317 is already really easy to work with, especially at 0.45mm/25G.

For the moment all I can say that it achieved was that it turned it blue Further testing needed. It would be nice if there was a way of making the wire immediately suitable for contact, but that may not be possible.