Powerman

Yes, you can extend the time. But you mention messages and display time, so what are you asking. You don't know the box that you set it in?

Well, I'm no electrical guru. I do know a couple things about heat transfer and fluid flow. I'm not seeing it. Single or dual, they are doing the same thing. If its a build problem, I would like to understand what is actually happening. I'm not used to not get things. But I'm not doing a very good job explaining what I'm not getting... well... because I don't get it. If it's a build problem, well, thats still physics. And its not clicking why spaced coils or dual coils seem to be such a problem with some. And if SS is at the ragged edge of usability as far as low TCR, then fine. I still like SS. If the low TCR simply shows problems where other materials easily cover them them that's fine too.

So, single coil... Match air flow to vapor production to preferred taste. Now add another coil. You need more air to produce same density with the increased vapor production. Double the coil, double the power, double the air needed. Double the surface area, doubles heat transfer. It's not a guess. It's an equation. Double the surface area, double the heat transfer. The whole point of multiple coils is to increase surface area to increase vapor production. So regardless of the hypothesis, heating cooling isn't slowed. It's not a static environment cooling by ambient conditions. And we are talking many times a second. There is not a slow down in cooling. It is heat. And it is heated then not, then heated then not. The biggest influence is vapor production and air flow.

That might be in the case of ambient passive cooling, but that is not what is happening in our application. If TC is stable and putting out 30w at 450F, only 1 or 2 of those watts are going to maintaining the wire at temp. The other 29 is going to vapor production and changing juice to vapor. And that is dependent on how much air flow is going past the coil. The air flow is carrying heat. So in our application we are actively cooling the coil with juice and air. And in that case, we are carrying away plenty of heat. Twice the surface area, with twice the juice and air flow will cool it twice as fast.

I did have a minute to change settings before going to work. What was I thinking.... I was just thinking I didn't want "no" preheat.... I put everything at 1 for 0.1 sec. I turned my crown profile up to 150w and I'm at 500F. Ya, it's fast. Not waiting on warmup. And yes, it's much smoother. Not by the graph, just by the seat of my pants. Haven't looked at device monitor yet. But the vape is plenty fast and smooth.

While I understand the thinking, heat exchange is directly dependent on surface area. During the cycle, say 100 times a second, you are still pulling air, the coil is still driving vapor production (read transferring heat) and the dual coil has twice the surface area of the single coil to do that. Heat exchange, cooling, will be twice the rate. Effectively making the dual coil cooling equal to the single.

I really appreciate the advice. Yes, all my decks will be velocity style. I keep the legs straight just because that's convenient for split post. I'm using 24g now. I got some bigger tank decks so will be going 8/9 wraps at maybe 3mm. You've given me plenty of tips to try out. So, TC sees whole coil. There are hotter parts of the coil, but the resistance rise is the averaged/summed hot/cool spots of the coil. I guess I just don't get why dual or spaced coils have such an effect. That's is for improperly built coils. I mean you have given plenty of reasons... Low TCR, pre-heat, unequal coils, misrepresented or poor forming of material... And that proper builds will act right dual or contact. Now I'm just trying to figure out what about the improper build is changing performance.

So I have heard about not using pre heat. But have been reluctant. That's one reason I like the DNA. But I see what you mean. Turn up power and let the board do it. I'll give it a shot. I have been using a couple Crius tanks. The ohms are stable. But I couldn't tell you there are no issues. I have a couple others coming so we'll see how it goes. I like your logical approach. Trouble shooting 101 in my line of work. But I threw some builds with a new wire and here we are. So I will back up and see. But is there anything to what I was asking? Why does TC not see the whole coil? Or am I just thinking wrong. I have another issue or multiple issues and TC just is getting what it needs to work right. Build problem and not a physics problem?

Thanks. It was an interesting read. I read this thread, and the links to the other threads. 8m not using ohm lock. And that's what's confusing. The discrepancy between what resistance the mod reads, cold, and what TC reads to limit power. I made contact coils, and had to use 170 TCR. I made 3 spaced builds, and the 138 worked. But even that isn't stable. I've had to walk the two I'm using up to 600 for same results. I analyzed all and the resistance was stable. Fine if it changes, but TC should account for that on baseline readings. I'm just not getting how resistance can stay the same, but TC is going off something else. Meaning anemic or having to keep bumping temp up. Even letting it sit can give different results hot or cold. Too much power or not enough. Very inconsistent.

That's reasonable, but the point of contact coils is even heating and less hot spots. So if it's only seeing a part of the coil, it should still even out better than spaced.

So my post above is a little disjointed. This is what I mean... Single coil, TC applies power within set limits, monitors resistance, and modulates temp. Yet contact coils do not seem to work so well. I could understand if it is basically shorting the circuit. Power cuts across wraps, TC sees resistance rise in one part, cuts power. But if it sees the rise in one part of the coil, and not across all of it, then why does it not see shorted resistance for base line? If it is only regulating one part of the coil, it should only see part of the resistance. Now dual coil. Identical for this argument. Half the resistance. But for same results of single, it need twice the power. TC sees resistance rise, but across double the mass. So double the mass requires twice the power to input heat to get temp to set point. Yet many report cold vape on dual. I can understand greater heat Flux and heat transfer/dissipation, but that's the point of TC... Continental to apply full power within setting until it reaches temp. So if dual half the resistance, then resistance rise is also shared and temp will be reached. It's just that it's taking more power to do that. Yet contact coils, and with same effect dual coils, that seems to be bypassed. It's only applying less power for cold or anemic vape. So it is seeing a resistance rise, and that doesn't matter what wire it is, yet the full coil mass, being contact or dual, isn't heating to full temp. In power mode, it doesn't matter. Full set power is delivered for full time and you get what you get. So why?

So this bleeds into something I've been trying to figure out on contact or spaced coils. I got some 430 and built some dual 24g coils. But I had to run the TCR up to 170 to get it to fire right. Too cold. I've been trying to wrap my head around why. TCR is TCR. If I have to fire harder, then it is not seeing the heat rise. In TC, it's going to keep giving power until it sees it. But it's seeing a resistance rise and cutting power. So some of it here is helpful concerning heat Flux and symmetrical coils. What I'm not getting is that even though it isn't giving desired temp, it is seeing a rise in resistance. If there is a hot spot or uneven coil, there could be spots of higher resistance, but combined it is not that way across the whole circuit. If resistance is higher in one coil, current should flow to the other one heating up to equal resistance.

So the point of this was I got some 430 SS and put the 138 TCR in from steam engine. But the vape was very anemic. Dual 24g 9.5 wraps at 2.5 mm coming in at 0.16 ohm. I had to bump the TCR all the way up to 170 to get it to run right. That was a contact coil. I built 3 spaced coil decks and all work right with the 138 TCR. So fine I have to do spaced. I just want to know why.

I asked this on another forum. I C&P here. Hopefully it's not that much out of context... Honestly, I'm still having a hard time wrapping my head around this. In any circuit you can get a short. So a wire 10 cm long between +/- terminals has X resistance. Coil it, loop it and touch only the tops together now you have a short. Not the distance between the two +/- terminals is 2 cm. Who cares... Except now 2 cm of wire only has 1/5 the resistance of the straight wire. So this is the part I don't get. I can only assume. I going to use numbers straight out of my ass to illustrate the point. I assume measuring the effect of temp on resistance is on a material at a equal temp. So 2 cm of wire at the same temp for the whole length of the wire. 2 cm wire with 1 ohm at 100 degrees. Heat it up to 200 degrees it has 2 ohms. But if 1 cm is 300 degrees, and 1 cm is 100 degrees, the average is 200 degrees. 2 ohms. If a coil is contacting only at the top, and current is shorted, I could see the short heating up much hotter than the rest of the coil. I could see TC limiting power because it sees the rise. The top is hotter than the bottom and the average is the rise. But if there is a short, then that 10 cm wire is now only 2 cm. And the natural resistance of the wire would show that. 10 cm with 1 ohm is now 2 cm with 0.2 ohm resistance. The part I don't get is why does my mod see the full resistance of the full length of the wire, but TC seems to only see the rise in one small part of the wire. Path of least resistance should be measured. A 10 cm length of wire shows 1 ohm on mod, not 0.2 of a shorted contact coil? I hope that makes sense.

Most folks are finding you can't use contact coils in TC. Yes that's known for nickle, but it seems to be the case with SS as well. Sure contacts can "work", but erratic and inconsistent performance. Makes sense to me. I have not had time to do some spaced to check performance. Seems with SS there has been a rash of problems. People seem to look at tank and mod and wicking and so forth. But it's common problems. Burnt hits with no obvious wick problem, or way too cool vape. Where as most resort to higher TCR or fake out ohm. Locking ohms is another one. Many people report rock steady reading on spaced coils. That's what I'll be doing next. I've also heard no preheat or higher ohm builds. But I'm suspecting those are bandaids to the real culprit.