Setting resistance for consistant temp control

[sofarsogood]

I've been using temp control exclusiively since the summer of 2015. I'm looking to make TC more consistant from one build to the next. Currently I'm building 1.4 ohm 30 guage stainless builds on a single coil rda.

To set resistance I compare the resistance reading of the build on a stand alone ohm meter and what the mod reads to see if they agree (usually they disagree by .03-.05 ohms). Usually I set and lock the resistance at the higher of the two readings and do a cotton singe test. I want the cotton to singe ever so slightly at 420 F and not below that temp. I'm adjusting resistance until the cotton test behaves as i want. (Arctic Fox firmware allows me to dial in any resistance value for a given profile and lock it.) It's not clear to me why I should leave resistance unlocked so it can wonder and why not set it so there is always a constant result? This is a fresh experiment. I rewick every couple of days. I'll do cotton burn tests on those occaisions to see if the locked resistance is still singeing the cotton at 420.

Probably there are people here with more experience working with this. Is there a flaw in my approach?

 

[Eskie]

With your Pico locking the resistance is probably fine so long as you don't go through major ambient temp changes, like walking outside from room temp into an arctic blizzard, as that will obviously effect the "cold", or resting resistance, of the wire. Other types of boards such as dna boards work better without a resistance lock as it keeps refining the resting resistance over time.

My only thought is instead of locking in a resistance that you enter, instead of what the mods reads on a cold/ambient temp coil, is to adjust the TCR instead. That's something you can do without relying on using a software package to access an "enter resistance" option, and can be adjusted right on the mod (the Pico does allow you to use custom TCRs right from the screen in setup, doesn't it?).

 

[GeorgeS]

Outside of DNA devices (which I've mostly given up on) I'll lock my resistance at the time of the build. Any refills or rewicks keep don't get the coil resistance reset.

Admittedly, some tanks/mods I'll run a little hotter/colder than the rest of the fleet however I just adjust temperature to where I like the output and flavor.

Lately I've been using an experiment. With the coil not flooded with fresh juice I'll set the temperature to 450F and slowly move the wattage up (from absolute minimum) between fires to see where the natural boiling point is. (works best on mods WITHOUT a hit timer) Once the natural boiling point is found I'll reset my wattage to 15-25W and the temperature to the boiling point.

On some mods it ends up being 330F and others 360F.

The point of locking or not locking the resistance is to have a consistent vaping experience.

 

[sofarsogood]

With your Pico locking the resistance is probably fine so long as you don't go through major ambient temp changes, like walking outside from room temp into an arctic blizzard, as that will obviously effect the "cold", or resting resistance, of the wire. Other types of boards such as DNA boards work better without a resistance lock as it keeps refining the resting resistance over time.

My only thought is instead of locking in a resistance that you enter, instead of what the mods reads on a cold/ambient temp coil, is to adjust the TCR instead. That's something you can do without relying on using a software package to access an "enter resistance" option, and can be adjusted right on the mod (the Pico does allow you to use custom TCRs right from the screen in setup, doesn't it?).

I don't know how to fiddle with TCRs to get a given result. If resistance of a given wire changes with use or wear or what ever it would be interesting to hear an explanation for that. My understanding is the resistance setting is reletive, not absolute so if the set resistance singes cotton starting at 420 shouldn't the temps vary consistantly after that?

Two things got me started on this. First was Arctic Fox firmware letting me see watts and temp after each puff. The other is the thread about unsafe temperatures. I'm confident my vape has always been cooler than the temps claimed to be concerning but I'd also like to have a vape that's no warmer than it needs to be to keep me happy and consume less power so a single 18650 gets through the day better. I switched from 28 guage stainless to 30 guage starting yesterday. The results are promising so far. 30 guage comes up to heat a lot faster than 28.

 

[Eskie]

Remember the "temperature" you're seeing is a calculated value based on the resistance as current passes through. How accurate that temperature is will be influenced by the quality of resolving the resistance value, relying on the TCR as a guide. Remember the TCR is an average as wires generally do not change resistance in a linear manner (which is why some mods use curves for their calculation). The temperature will be most "accurate" when the resting resistance compared to the resistance with current load is reliable and reproducible.

 

[sofarsogood]

Remember the "temperature" you're seeing is a calculated value based on the resistance as current passes through. How accurate that temperature is will be influenced by the quality of resolving the resistance value, relying on the TCR as a guide. Remember the TCR is an average as wires generally do not change resistance in a linear manner (which is why some mods use curves for their calculation). The temperature will be most "accurate" when the resting resistance compared to the resistance with current load is reliable and reproducible.

I mostly understand that. In the early days of temp control the youtube reviewers would do the cotton burn test at 420 degrees. Somewhere, somehow that temperature was made the bench mark. If i can't singe cotton until i set to 420 degrees wouldn't i be somewhere in the ballpark of accurate? After doing that test I set temp to 360, 110 F south of the scary 470. that gives me a large margin for error. Never the less without a physical test like cotton burn what other way is there to be sure of the temperature at at least one point in the settings? ...which gets me thinking, is there some other material that singes or reacts some other way at some other set temperature that could be used for a second reference point? A second test might shed light on whether the cotton test is accurate. Hmm...

 

[Eskie]

There's a water boiling test which will give you a 212F set point. I've never done one, but there's a protocol somewhere around here to do it. I think if you know your 420F set point, and you're going to be vaping within 50F of that, a second point for accuracy won't add much. I also wouldn't focus entirely on that 470F point. We've been knocking that around for 120 pages already and still can't be POSITIVE that will be the magic number. If you're at 360 to even 400 if your TC board is off over 10% you're still in a safer zone.

 

[sofarsogood]

There's a water boiling test which will give you a 212F set point. I've never done one, but there's a protocol somewhere around here to do it. I think if you know your 420F set point, and you're going to be vaping within 50F of that, a second point for accuracy won't add much. I also wouldn't focus entirely on that 470F point. We've been knocking that around for 120 pages already and still can't be POSITIVE that will be the magic number. If you're at 360 to even 400 if your TC board is off over 10% you're still in a safer zone.

I understand that the 470 F value is somewhat artifical and not confirmed in vaping devices. So far what I'm finding is my vape is a lot cooler than I thought. There are vapers who say they like to be at 550 F. if they don't have a dna power device or something similar like Arctic Fox they can't be sure if their vape ever reachs values like 550.

I just did a bit of searhing and found infrared temp measuring instruments that are cheap and claim +/- 1 F accuracy. If they can get a valid reading from a coil that would be the best way to calibrate a build.

 

[Eskie]

I understand that the 470 F value is somewhat artifical and not confirmed in vaping devices. So far what I'm finding is my vape is a lot cooler than I thought. There are vapers who say they like to be at 550 F. if they don't have a dna power device or something similar like Arctic Fox they can't be sure if their vape ever reachs values like 550.

I just did a bit of searhing and found infrared temp measuring instruments that are cheap and claim +/- 1 F accuracy. If they can get a valid reading from a coil that would be the best way to calibrate a build.

Yeah, that 550F use makes me wonder if one, it's real, and two, if it is how can they stand it? Those infrared guns have two problems. The area they read (it's like a flashlight and not a pinpoint reading), and it's really tough pointing them at a coil that's inside a metal chamber. At least with a cotton burn test you know the coil temp has to be 420 or the cotton won't burn.

 

[sofarsogood]

Yeah, that 550F use makes me wonder if one, it's real, and two, if it is how can they stand it? Those infrared guns have two problems. The area they read (it's like a flashlight and not a pinpoint reading), and it's really tough pointing them at a coil that's inside a metal chamber. At least with a cotton burn test you know the coil temp has to be 420 or the cotton won't burn.

The coil can be fired while it's exposed. If the tc function is working accurately the coil will stay at the correct temp as long as nothing is cooling it too actively. May be there are infrared sensors with a very small focus. The cotton test is what we have. Then I go by my own principle I call the arrowhead hypothesis which says, f there is one way to do something there's a good chance there's at least one more way and may be that way will be better than the first way. Many years ago I found a stone arrowhead lying in the middle of a driveway on the family farm. I wondered, is that the only arrowhead in that road or, if I search, while i find one more. I searched and found one more.

 

[Eskie]

Some of the more convincing test stuff was what @mikepetro did with the thermal camera back in the temp thread. He seemed to get some fairly accurate measurements with that.

 

[sofarsogood]

Some of the more convincing test stuff was what @mikepetro did with the thermal camera back in the temp thread. He seemed to get some fairly accurate measurements with that.

Thanks, thermal camera sounds expensive. We have the cotton burn test that anybody can so for no cost. Now I'm looking for a second way for low cost or no cost. There probably is one. The people who sell the cocnsumer grade infrared devices claim +/- 1 F. That's way better than good enough but may be it needs to be a device that can focus on a very limited area because coils are small or may be those cheap devices will work.