HugeEgo

One of those guys on ECF with "supposed" experience in the wire industry is a former aerospace engineer who specifically worked with titanium and titanium alloys in aircraft designs. He has papers published in the scientific literature and is an expert on the metal and its properties. (Drucker is his handle on ECF, iirc). There was another guy, too, who was an engineer at Corning. He chimed in and said it's all BS as well. So, yes, these guys are fully qualified to say that SSV is full of crap (and they are). Any time you hear marketing terms like "special blend" or "proprietary secret" you know it's BS 99% of the time. SSV is a vape company -- not a wire extrusion factory. They are merely buying their wire from some factory somewhere that probably sells it to 1000 other clients in various industries. They have no secret recipe. They don't even have engineers or metallurgists. It's just a couple of guys who own a vape shop making up stuff so they can charge outrageous prices for wire. Are you going to believe SSV (who have no expertise, no credentials and have a profit motive) or are you going to believe former aerospace engineers who used to study titanium for use on aircraft?

Try the TFR curve for 430 SS and see if that gets you in the ballpark.

It's titanium, so it will be as safe as any other titanium. TEMCo is reputable and sells high-quality (usually made in the USA) wire. Their Kanthal, for instance, is made by Sandvik themselves. You can e-mail them and ask. They usually respond to e-mails very quickly.

The grade doesn't matter for advanced users (like most of us DNA-200 users), but it does matter for new TC users who buy SSV Ti wire and throw it on their Joyetech TC mod. It's not going to work at all. New users will be forced to go hunt down the SSV TCR value, which they probably aren't going to do. Because I can buy grade 1 Ti wire all day for about $10 for 50 feet. SSV charges, what? $1 per foot? Grade 1 is the purest commercially available and thus it will be the closest to the TCR values found in scientific literature for pure titanium.

First of all, SSV's wire is not grade 1. And second of all, no it is not worth the money.

Blasphemy. VapeBros before Hoes.

Yep, I think you are onto something. The change in voltage and/or amperage needed to maintain the temperature are too small to do on the fly accurately (or at least this is the best explanation in my non-EE view).

Yes, all of that is correct. Another way of looking at it for a given coil is to use the steam-engine formula for "TC Precision" (TCR * R * 1,000,000). However, consider the following: Let's say we vape at 232°C (450°F) and assume the room temperature is always 20°C. Now, let's calculate a few different scenarios for various wires. I chose these at random using a 3mm bit with roughly the same wraps for each. 316L stainless: Initial resistance at 20°C = .341? Final resistance at 232°C = .409? TCR = .00094 Total ?R = .068? Total percent increase in R = 20% Ti Grade 1 coil: Initial resistance at 20°C = .247? Final resistance at 232°C = .439? TCR = .00366 Total ?R = .192? Total percent increase in R = 78% Ni-200 Coil: Initial resistance at 20°C = .05? Final resistance at 232°C = .114? TCR = .006 Total ?R = .064? Total percent increase in R = 128% As you can see the total change in resistance is 128% in nickel, 78% for Ti, and 20% for 316L. Even though the absolute rise in R (316L and the Ni-200 coils had almost the same total change in R) is not that much different, I think the overall change in resistance relative to the starting resistance of the coil is somehow affecting the accuracy. Whether this can be overcome, I do not know. TL;DR -- Ask John. I would be interested to know as well.

I am using a dual coil 26ga 317L build right now (.270 ohms). My board reads it fine, but it seems to go back into power mode if I make a single coil build. But in dual coil mode, it works great and seems pretty accurate using the default 317L .csv file from steam-engine. I would test it with my thermocouple, but it's very hard to get an accurate reading due to the fact the thermocouple end is made of metal and shorts the coil. And I haven't found something suitable to insulate the thermocouple without drastically affecting the accuracy.

It's really not Evolv's problem. It is one of those "it is what it is" type of things. The TCR of 316/317 SS is what it is. Evolv can't change the laws of chemistry. Is it possible they could make improvements to the board in the future to compensate? I suppose it's possible, but I doubt this is something that could be improved upon with firmware updates. It would take an even more accurate ohm reader (that can read beyond the milliohm range -- say in microohm range). I don't know if this is physically possible to do with current technology, at least not accurately for our application where we are screwing in atomizers with 510 connections, etc. It's already hard enough to get an accurate milliohm reading. But I could be wrong, I am not an EE.

Yeah. I don't know why anyone still uses Ni-200, tbh. Can't be dry burned (can't be cleaned), have to recoil every couple days, and it has a super low resistance which is annoying. To each their own, though.

I use Ti and SS (317L and 430). As for nickel, I look at it as "why bother?" I haven't tried any of the NiFe alloys and probably won't because they contain, well, nickel (yes so does 316/317 SS, but in much smaller amounts).

My board won't read 26 gauge 317L wire without jumping back to wattage mode. If I use dual coils, it reads it fine. It's strange. (317 is pretty much the same as 316 with a slightly lower TCR).

Are you using stock Herakles heads or an RBA with your own wire? If it's the former, then it's probable that the wire they are using in the herakles is not really 316L. I know I've experienced this with Joyetech "316" stock heads. They are closer to 304 grade than they are 316. I suspect these Chinese companies are using the cheaper 304 wire and simply calling it "316" when it's not. Try a TCR of about .001016 and see if that improves it (that's the TCR of 304). There's nothing wrong with using titanium coils, which are much more accurate due to the higher TCR. Set your mod at 0.00366 and vape on.

I've got a spool of 28 gauge and it works well. It is certainly more accurate in TC mode than 316/317. I don't use it much, though, because I am leery of its durability. It isn't as corrosion resistant as the 300 grades. @Lance, why are you using the 304 .csv file for 430? Steam-engine has a 430 .csv file posted.

28 gauge 430 SS works about as well as Ti for me. You can get 430 SS wire (as well as 317L) from unkamensupplies.com. The downside is 430 is not as corrosion resistant as 316/317. Personally, I just keep going back to Ti. I am not sure why so many people refuse to use it (I guess because of the scare of TiO2 which is completely overblown). 316/317 SS just isn't a great TC wire because it just doesn't have a high enough TCR. Another option is to use one of the Iron-nickel alloys (Nifethal, etc.). Or if you're a high-roller, you could buy some 32 gauge sterling silver or platinum wire and vape like a rockstar. Finally, I think it's possible that some of the wire from China (UD) is not the correct alloy. This could explain some of the weird results people are getting. I know that Joyetech labels some of their coils as 316 SS when it most definitely is not 316. Just as one example. Unkanmensupplies claims their wire is made in the USA so the wire they sell is most likely following the proper ASTM specs. The Chinese do things their own way and often don't follow western specifications or standards. Not that their wire is bad or unsafe, but it might be "different," which can throw TC off. Go to Fastech and look at their Ti wire. None of it is labeled as grade 1. Someone asked FT what "grade" the wire is and they responded "There are no grades in China." So it might be grade 1 or 2, or it might be grade 5. I am sure it really is Ti wire, but it might not match up exactly with CP Grade 1 wire made to western specs.

Go buy some 430 SS. It's TCR is higher and it generally is less of a PITA to work with.

I don't think SSV knows what the proper curve is because what they are selling is not grade 1 titanium wire. All of the literature I've seen for Ti TCR values relates to pure titanium and not these alloys. Of course, it's possible they (or others on their behalf) have tested the wire at various known temperatures and resistances and charted the TCR, but I doubt it. And TCR has nothing to do with the diameter of the wire -- it is an inherent property of the metal.

The reason I commented about your temps is because I am quite certain that unless you are vaping distilled water, you are not going to get any vapor at 250F. Just won't happen. The boiling point of PG is 380F and the boiling point of VG is about 554F. A mixture of the two will fall somewhere in between. This means that your coil is screwed up somehow or your tank is not making a good connection and is messing up the resistance reading on the DNA. Are you using the Kanger Ni-200 stock coils? TL;DR -- You're not vaping at 250F. The reading on device monitor is wrong. There is a problem with your tank or coil.

Just curious, are you using F or Celsius? If you're using Fahrenheit, then that must be a pretty cold vape at 250°.

What about nickel free (>1%) SS 430 ?[/QUOTE] 430 has less corrosion resistance than 304/316, but it is nickel free and has a higher TCR. So, it's a trade-off.

Steam engine's TCR values are listed for the "vaping range." If you look up the TCR of titanium at 20°C, you will usually find .0035. However, that is for room temperature. In the vaping range the TCR changes from .0036 to .0037. This is where Steam-engine gets the value of .00366. So, Daniel plugged in .00366 as his TCR number, which IS the same thing as a .csv curve. The .csv file is simply a file that provides a TCR number for a certain temperature (since most metals have varying TCR's depending on temp). This allows the user to put in the exact TCR number for, say, 450F. However, 0.0036 is going to be very close throughout the whole vaping temp range. As for why his .csv provided a less accurate temp, I don't know. It should be exactly the same as inputting the TCR manually. Perhaps he used the wrong file. If you're really concerned about it, go buy a thermocouple probe and test yourself. You can get cheap Chinese digital thermometers for around $20.

304 SS is not as corrosion resistant as 316 and both alloys lose corrosion resistance with increased temp. From that pic, it looks like the 304 is the culprit (which makes sense). Generally, the lower the carbon content of the steel, the better for corrosion resistance. You're using standard 304 and not 304L. I think for vaping, the "L" grades are likely always best. Eliquid chemistry is more complex than many give it credit for and there's an organic chemistry soup in there that is probably harsh enough to corrode some metals, especially at high heat. If you want to use SS, it's best to probably go with 317L, which has the highest corrosion resistance of all (readily available) grades of SS. 316L would be the 2nd best. If I were you, I would put some of the 316L in a build by itself and then some 304 (if you have any thick enough) into a build by itself. Use the same juice for both and fire them for a while and check the results. Here's a chart on the corrosion resistant properties (from various chemical attacks) of 304 and 316. Lots of other good info out there in google land.

I see various values for the case cooling setting. Here's mine: Case Cooling Constant: 424.42sCase Heating Constant: 245.79sUSB Temp Rise: 9.15°F °F/A 15.01 This was ran with an atty on top and a silicone sleeve on my mod.

It will be about the same vaping time that a series box with 2 18650's will allow you. 1850mAh 3c LiPo = 20 watt/hrs 2 (2500mAh) 18650's in series = 18.5 watt/hrs 2 (3000mAh) 18650's in series = 22.2 watt/hrs So, the Lipo falls right in between the two. Very similar vape time between it and the 3000mAh 18650's. That is assuming you can build or find a mod with a 1850mAh Lipo in it. Also, keep in mind that the Lipo pack will likely be more stable with less sag at 100W.