DNA 200 Stainless Steel 316L - Not reliable

[AlphaDog]

So, I originally tried out some SS316L wire using my DNA 200 mod and came out of the experience a little baffled.

I loaded the Steam Engine 316L csv and set my temp to 450F. It worked at first, then I noticed that if I left the mod standing for more than an hour, it would then prematurely cut power while vaping. Setting the temp to a higher value would remedy this for a short while, until the cycle repeats.

I then read somewhere that the 304 csv should instead be used, the same behaviour occurred with this too. I tried locking ohms as well, and I can't get a consistent, reliable TC vape. I also changed the TCR value which didn't help.

What is the definitive, tried and tested way to achieve stable temp control from SS wire using a DNA 200 mod?

I'm a bit miffed that at such a price premium, it doesn't work... It should be preloaded with these settings for crying out loud.

 

[BuzzGlo]

Been using ss316 I noticed something like this last night as well. Mine was the other way around, Suddenly the vape was way hotter. Vaped 90w@220 for an hour put the mod down for a while had to drop it 75w@200 there after.

 

[AlphaDog]

Yes, I can't find any info on how to get this working properly anywhere.
I don't have a problem sticking with Kanthal for now though - I guess we'll just have to wait for new firmware or something to get this sorted.

 

[BumbleBee]

I'm having the same experience with SS on my DNA200, RX200 and VTC Mini. Temp control with SS doesn't seem as acurate as with Nickel.

 

[AlphaDog]

I'm having the same experience with SS on my DNA200, RX200 and VTC Mini. Temp control with SS doesn't seem as acurate as with Nickel.

From what I've read, stainless steel wire's resistance does not change very much as it heats up, compared to say, Nickel wire... So this means that it's harder for the chip to detect the subtle resistance change, and therefore it's harder to predict the actual temp of the wire.

However, the DNA 200 chip is supposed to be the most sophisticated temp sensing chip out there - yet there are far cheaper mods, with preloaded profiles for a whole host of wire types mind you, running stainless steel wire in temp mode with great success. (Cuboid, eVic VTC Mini, etc)

 

[Ezekiel]

Hi guys

First of all, this problem has nothing to do with the CSV file / TFR of the mod. Although there could be a number of factors, most of them come down to how well your mod can read the initial (cold) resistance and how much that cold resistance changes over time. A lower measured cold resistance than what is actually on the atty will give a warmer vape, and a higher cold resistance will give a colder vape. And usually, the culprit is the low TCR of stainless steel, or bad connections/bad builds. And before anybody says anything, I've had just as many issues with SS on other mods than the DNA.

Unfortunately (or ironically), it is the DNA's sophistication that can often make a bad problem worse, if not configured properly. The reason is that the DNA200 chip tries to refine the cold resistance as much as possible, in order to make sure that it is actually the cold resistance. If there are any a) connection issues, b) mod resistance issues, c) fluctuating cold ohms (due to wire/wick expansion, screw loosening etc.) or d) ambient temp measuring issues, your TC will perform much worse on a DNA than another mod.

You can try the following though:

1) Make sure your atty has a stable connection. Looking at the "Atomizer Analyzer" in Escribe, slowly connect and disconnect your atty. If there are large resistance fluctations (as large as +- 0.01 can be significant), then you've got a bad 510 connection. This is can be either a too-loose or too-tight atty, and can seriously mess up TC
2) Do the same for the wire screws. Heated wire can some times loosen screws a bit, thereby worsening the connection and ruining TC
3) Try unlocking/locking your resistance, or even overriding (again, in the atomizer analyzer) it. Locking your resistance is a decent idea on other mods, but usually not the solution on a DNA. IF you have tried (and properly tried) vaping with it locked, try unlocking it and giving the DNA's refinement algorithm more freedom. On the other hand, you can try to lock it if you've properly tried vaping with it unlocked.
4) Try locking/overriding your ohms a little bit lower than what is actually measured - it will generally stop the refinement algorithm if that is giving issues.
5) Make sure that your mod's internal resistance has been set and is accurate. Usually, you can get this from the manufacter, altough you can supposedly measure it yourself as well. You can test whether this is the problem by changing it to 0.00 ohms, and seeing whether it changes the nature of any TC problems you have. An incorrect (usually too high) internal resistance will give you a world of trouble with TC accuracy, especially for stainless steel. It is also generally a unique problem for DNA200 chips, where the chip is put into different mods which might have different resistances.
6) Make sure you've run the Case Analyzer. It helps to give an accurate reading of ambient temperature, which in turn, will give the refinement algorithm more accuracy.
7) You can enlarge the Ohm lock range from 25% to 40%. Any resistance change on your mod above 25% and when the resistance has been locked, will be assumed to be a new coil and it will change the cold resistance to the new resistance. A particularly shifty atty will find a lot of benefit from a larger Ohm lock range, and you will have a more consistent cold resistance.


Beyond these issues, I will always recommend either using a different wire type, or building higher resistance coils. Most of the issues with TC (such as bad connections, incorrect mod resistances, ambient temperatures and whatnot) are actually present with other wire types as well, just with a lessened effect. With higher resistance stainless steel coils (at least higher than 0.4 or 0.5 ohms), any inherent TC problems becomes considerably less bad.

You can scour my (yet incomplete, but at least newly updated) guide for more information!

 

[AlphaDog]

Thank you for the indepth response. I have made sure that the connections are stable. I think that the problems might stem from me working in an air conditioned office, and then taking the mod outside and vaping... the ambient temperature flux might be the root cause of the issue. What are your thoughts?

 

[KB_314]

From what I've read, stainless steel wire's resistance does not change very much as it heats up, compared to say, Nickel wire... So this means that it's harder for the chip to detect the subtle resistance change, and therefore it's harder to predict the actual temp of the wire.

However, the DNA 200 chip is supposed to be the most sophisticated temp sensing chip out there - yet there are far cheaper mods, with preloaded profiles for a whole host of wire types mind you, running stainless steel wire in temp mode with great success. (Cuboid, eVic VTC Mini, etc)

The new escribe update (it might still be a beta version) has SS316, Nickel and Titanium presets. In lock mode, holding all 3 buttons will get you to these presets. I have it installed and have used SS, but only for an hour or so - not enough to know whether it's working properly. Wouldn't say it was the most consistent vape, but I'd put it down to my own build issue or just lack of experience with TC. Thoroughly enjoying the SS316 in power mode though!

 

[Ezekiel]

Thank you for the indepth response. I have made sure that the connections are stable. I think that the problems might stem from me working in an air conditioned office, and then taking the mod outside and vaping... the ambient temperature flux might be the root cause of the issue. What are your thoughts?

Man, TC can be a pain sometimes.

It is probably the temp differences. The DnA chip tries to determine the ambient temperature... but dont know how well callibrated that is wrt SA. As I said, you can try running the case analyzer, maybe it will help! Otherwise, just try locking your resistance when it is at its coldest (ie, in the AC office) - it should work better than locking it when outside. I honestly think increasing the lock % might help in that case as well.

Unfortunately, I dont actually think the DNA will be the best chip on the market... but it will definitely help whoever builds the best chip. This is unfortunately a research and tinkering device more than it is a fully qualified (amd price worthy) fantastic vape...

Sent from my SM-G920F using Tapatalk

 

[Chronix]

Not sure if this helps but on my rolo DNA I can only get TC with SS316L working properly if I use claptons or staggered fused claptons - can never get it to work correctly with normal round wire.

 

[AlphaDog]

Not sure if this helps but on my rolo DNA I can only get TC with SS316L working properly if I use claptons or staggered fused claptons - can never get it to work correctly with normal round wire.

I got mine working (both rx200s and dna200) with any ss316 build. The key for me is that u need to ensure that there are no hotspots before setting it to temp mode. Also, i have found that spaced coils work best in tc mode.

 

[Dexter]

@Ezikiel's post earlier was spot on. Check all of those things first, but make sure you're using a spaced coil rather than a contact coil.. The csv from Steam engine is the correct file to use.
I use SS316L with my DNAs all the time, and the only way that your mod will pick up the change in resistance is if it's spaced.
Wrap it the same way as you would a contact coil. Once you're done, stretch it out while it's still on the mandrel and then compress it with your fingers again. It will come out perfectly spaced...
Also, don't forget, on the DNA you don't lock resistance, the mod automatically reads the cold resistance on your coil..