TC accuracy and wire selection

[Mr Numpty]

After much experimentation I can only report what I have found using the IPV D2, RDTA, Epoch D1, NiFe30 and Ti, which is that I haven't had a single problem from 0.1 Ohm and slightly lower dual coil set ups. I do mostly build around the .15 Ohm mark, but haven't found any noticeable differences between .15 and .1

What I have found is that builds over .2 haven't been as responsive to changing temp settings nor as stable and that those issues appear to increase with each .01 above .2 that I go.

What does it all mean @danb?

 

[danb]

What I have found is that builds over .2 haven't been as responsive to changing temp settings nor as stable and that those issues appear to increase with each .01 above .2 that I go.

What does it all mean @danb?

From a sensitivity point of view, things should only get better as resistance increases. I'm normally hitting the 0.17-0.20 Ohm area with NiFe30 and have no issues. I've not been any higher than 0.20 or lower than 0.15. Clearly there are other factors coming into play if you're seeing problems above 0.20 - I don't know what they are, but here are some ideas:

Maybe the larger mass of wire as you build at higher resistance is increasing heat up/cool down time, which is giving a less stable TC response. I'm just guessing here - would need a DNA200 to see the graphs. I've been a good boy this year, so maybe I'll have one soonish.

Another possibility is that as your number of wraps increases, you have to decrease wrap spacing and are more likely to get hotspots or uneven heating of the coils which messes up the TC. I have noticed this if I try to put more than 7 spaced wraps in my subtank mini - I end up with the legs touching the wraps at each end, which creates hotspots and the TC goes a bit wonky.

 

[Mr Numpty]

Thank you. This is probably nonsense but one theory I have contemplated is that, with the D2 only firing TC coils up to .3, maybe it doesn't handle things as well when set ups over .2 inevitably go above .3 as they heat. Crazy?

 

[danb]

Thank you. This is probably nonsense but one theory I have contemplated is that, with the D2 only firing TC coils up to .3, maybe it doesn't handle things as well when set ups over .2 inevitably go above .3 as they heat. Crazy?

Hadn't thought of that, a NiFe30 will approximately double in resistance when you're vaping it, maybe there is something to it. No idea though - can you test these builds on a different mod to compare?

 

[Mr Numpty]

can you test these builds on a different mod to compare?

Not yet but I have an Evic VTC mini on the way which I see goes up to 1 ohm in TC mode so will see if that handles higher builds any better.

 

[sircumsized]

So am I to understand that higher ohm coil builds will have greater accuracy? I have a dual coil SS317 0.16ohm build and my evic vtc mini always jumps out from TC mode.

 

[Tubbyengineer]

So am I to understand that higher ohm coil builds will have greater accuracy? I have a dual coil SS317 0.16ohm build and my evic vtc mini always jumps out from TC mode.

Yes, higher resistance TC coils will have greater accuracy- but the problem you are having sounds like it isnt changing resistance enough for the mod to recognise it as a TC wire, check for shorts at the posts and look for hot wraps, make sure your coil isnt touching the deck or any other part of the chamber and finally check that it's not down to a crooked or too flush 510 pin on the atty or mod

 

[sircumsized]

Yes, higher resistance TC coils will have greater accuracy- but the problem you are having sounds like it isnt changing resistance enough for the mod to recognise it as a TC wire, check for shorts at the posts and look for hot wraps, make sure your coil isnt touching the deck or any other part of the chamber and finally check that it's not down to a crooked or too flush 510 pin on the atty or mod

That sounds like you're asking me to check for shorts. My Mod has short detection so its not shorted that's for sure. I've rebuilt with a 0.78ohms single coil and TC works perfectly now (also changed from 317L to 316L). I'm guessing I really do need a higher resistance TC coil.

 

[Tubbyengineer]

That sounds like you're asking me to check for shorts. My Mod has short detection so its not shorted that's for sure. I've rebuilt with a 0.78ohms single coil and TC works perfectly now (also changed from 317L to 316L). I'm guessing I really do need a higher resistance TC coil.

I AM asking you to check for shorts, Your mod may have short circuit protection - it's almost useless in this case - it only looks for hard shorts less than 0.01 resistance. If there is something shorting out a coil partway along or not a hard short it can hold the resistance change down to a level that the mod can't work with, thus tricking it into thinking it's not a TC Wire...

 

[Tubbyengineer]

That sounds like you're asking me to check for shorts. My Mod has short detection so its not shorted that's for sure. I've rebuilt with a 0.78ohms single coil and TC works perfectly now (also changed from 317L to 316L). I'm guessing I really do need a higher resistance TC coil.

Just for reference a 26 Gauge 316 SS coil with an inner dia of 2.5 mm and leg lengths of 1mm would have just 2.38 wraps at 0.16 ohms, so if you had 3 or more wraps on your coil there WAS a short somewhere...
(317 is actually higher resistance than 316)...