TC Tinkering

[McDudeson]

Hello all. First post here. I've been messing with TC on an IPV5 using NiFe70. I have been trying to make a dual coil, 15 wrap, 26 gauge build work in TC mode for weeks now. One of those things I come back to every now and then. Needless to say, I've been having trouble with it. The problem has been either anemic results, or dry hits and singed cotton. I've looked in to dual coil tc builds, and came across quite a bit of debate on why it would or would not work. Most of it centered around the idea that adding coils does not change the tcr of the build. After today, I disagree.

Steam engine has the tcr of NiFe 70 at .005250 so this was the tcr setting I've been using, and failing at. After some long pondering, I realized that my failure was stemming from the way the board operates. The board doesn't know you are using more than one coil, therefore it does not compensate for parallel resistance. VERY hypothetical example below:

Single .1ohm coil set at 450f increases resistance by .1 to achieve the desired 450 degrees. Ending resistance at .2. All is happy and well.

Dual .2 ohm coils, reads .1. Set at 450, both coils increase resistance by .1 to achieve desired temperature. In a parallel circuit, resistance is raised by .05, and this is what the mod sees. The mod thinks it needs to push moar power, and things go amiss.

I found I had to lower the set tcr on my ipv5 from 5250 to 4500, effectively telling the mod to expect less of a resistance change. Working perfectly now.

Am I off on my thoughts? Or am I just late in figuring out something that was solved eons ago?

 

[distortoblotto]

I run NiFe 48 duals in TC @ 55w and 450d all day long in a dna200 squonker. Keep in mind that cotton starts to burn at 400d. The wicks should be nice and wet. Don't know what atty you are using but the coils need plenty of air. Restricted air flow is usually always the cause for burnt cotton at the higher temperatures.

On another note, does the Yihi chip used in the IPV have a program for NiFe 70? The temperature coefficients can change drastically from wire to wire. A good baseline to start off with is 0.11-13 resistance @ 25w and 420d bumping up or down from there. At this setting burnt cotton should be virtually nonexistent.

 

[TheotherSteveS]

Hello all. First post here. I've been messing with TC on an IPV5 using NiFe70. I have been trying to make a dual coil, 15 wrap, 26 gauge build work in TC mode for weeks now. One of those things I come back to every now and then. Needless to say, I've been having trouble with it. The problem has been either anemic results, or dry hits and singed cotton. I've looked in to dual coil tc builds, and came across quite a bit of debate on why it would or would not work. Most of it centered around the idea that adding coils does not change the tcr of the build. After today, I disagree.

Steam engine has the tcr of NiFe 70 at .005250 so this was the tcr setting I've been using, and failing at. After some long pondering, I realized that my failure was stemming from the way the board operates. The board doesn't know you are using more than one coil, therefore it does not compensate for parallel resistance. VERY hypothetical example below:

Single .1ohm coil set at 450f increases resistance by .1 to achieve the desired 450 degrees. Ending resistance at .2. All is happy and well.

Dual .2 ohm coils, reads .1. Set at 450, both coils increase resistance by .1 to achieve desired temperature. In a parallel circuit, resistance is raised by .05, and this is what the mod sees. The mod thinks it needs to push moar power, and things go amiss.

I found I had to lower the set tcr on my ipv5 from 5250 to 4500, effectively telling the mod to expect less of a resistance change. Working perfectly now.

Am I off on my thoughts? Or am I just late in figuring out something that was solved eons ago?

it shouldnt work. The mod knows the wire, the appropriate TCR and the base resistance. It doesnt care what coil configuration you are using, resistance is resistance and it will increase according to the tcr curve whether its a single, double, triple-twisted dual back-flip with knobs on!! Its more likely your coils arent balanced/identical or the NiFe70 isnt NiFe70 at all...

 

[McDudeson]

I run NiFe 48 duals in TC @ 55w and 450d all day long in a dna200 squonker. Keep in mind that cotton starts to burn at 400d. The wicks should be nice and wet. Don't know what atty you are using but the coils need plenty of air. Restricted air flow is usually always the cause for burnt cotton at the higher temperatures.

On another note, does the Yihi chip used in the IPV have a program for NiFe 70? The temperature coefficients can change drastically from wire to wire. A good baseline to start off with is 0.11-13 resistance @ 25w and 420d bumping up or down from there. At this setting burnt cotton should be virtually nonexistent.

The atomizer is a sub zero. The IPV5 does not have a program for Nife 70. I have to use the manual tcr setting. I'm at .12, 450 degrees and 60 joules. I've yet to completely unravel joules vs watts.

it shouldnt work. The mod knows the wire, the appropriate TCR and the base resistance. It doesnt care what coil configuration you are using, resistance is resistance and it will increase according to the tcr curve whether its a single, double, triple-twisted dual back-flip with knobs on!! Its more likely your coils arent balanced/identical or the NiFe70 isnt NiFe70 at all...

I have to tell it what the appropriate tcr is because there is no program for NiFe (nifethal) 70. And yes, the resistance will increase the same. The difference is in how the mod reads the increase. If both coils in a parallel circuit increase by .1, the total circuit resistance increases by .05, thus throwing off the tcr curve.

 

[KenD]

Tcr is tcr. It's a physical property of the material, and the physical property doesn't change due to the number of coils.

Sent from my K6000 Pro using Tapatalk

 

[McDudeson]

Tcr is tcr. It's a physical property of the material, and the physical property doesn't change due to the number of coils.

Sent from my K6000 Pro using Tapatalk

I understand that, and agree. The mod uses the tcr curve to guesstimate the coil temperature based on resistance, correct? The mod expects the coil to increase resistance by X to achieve the desired temperature. In a dual coil setup, both coils being equal, the resistance increase to achieve desired temperature is actually X/2. The mod doesn't take this in to account. I'm trying to find a better way to explain my thought, the words are escaping me though.

 

[Flavored]

But the resistance of the overall circuit is R/2 as well . . . you're applying the parallel math to only the increase and not the base resistance.
An exercise for you: Do each coil individually for base (cold) and "at temperature" resistance. Put each of those in parallel (ie - the base resistance for parallel would be R/2 as well as the "at temperature" resistance). Then, compare that to the base and "at temperature" resistance of the parallel arrangement (ie - multiply parallel base resistance by 1 + tcr * T). You'll wind up in the same spot.
Parallel temperature control will work provided you get good connections for the coils.

 

[McDudeson]

But the resistance of the overall circuit is R/2 as well . . . you're applying the parallel math to only the increase and not the base resistance.
An exercise for you: Do each coil individually for base (cold) and "at temperature" resistance. Put each of those in parallel (ie - the base resistance for parallel would be R/2 as well as the "at temperature" resistance). Then, compare that to the base and "at temperature" resistance of the parallel arrangement (ie - multiply parallel base resistance by 1 + tcr * T). You'll wind up in the same spot.
Parallel temperature control will work provided you get good connections for the coils.

Man that f'd me up. Correct me if I'm wrong, but your exercise is telling me to compare two coils in parallel to a parallel setup. Trying hard to wrap my head around it. My initial thought is that the base resistance is irrelevant. Not trying to flame, just trying to understand.

Imagine this: you have a single coil at whatever resistance it may be. You heat it to 400 and, hypothetically, that coil increases it's resistance by .2. Now, you take two identical coils, again at whatever resistance they may be, in a parallel setup and heat it to 400. Each individual coil increases it's resistance by what? And the whole setup reads what? My thought is that each individual coil increases it's resistance by .2. The setup as a whole only increases by .1. Is this wrong?

 

[Eskie]

The mod only sees the resistance mounted on your tank's posts. It doesn't matter, or the mod care, if there is one coil or 4 coils all mounted to create a total resistance of say 0.2 (4X0.8 ohm coils, 2X0.4 ohm coils or 1X0.2 ohm coil). The resistance change when heated, as determined by the material's specific TCR, doesn't vary based on the number of coils mounted, only on the material and the power applied.

 

[Flavored]

Man that f'd me up. Correct me if I'm wrong, but your exercise is telling me to compare two coils in parallel to a parallel setup. Trying hard to wrap my head around it. My initial thought is that the base resistance is irrelevant. Not trying to flame, just trying to understand.

Imagine this: you have a single coil at whatever resistance it may be. You heat it to 400 and, hypothetically, that coil increases it's resistance by .2. Now, you take two identical coils, again at whatever resistance they may be, in a parallel setup and heat it to 400. Each individual coil increases it's resistance by what? And the whole setup reads what? My thought is that each individual coil increases it's resistance by .2. The setup as a whole only increases by .1. Is this wrong?

Oh, I can tell you're wrapped around the axle on this a bit. My head spun a bit, too. But you are looking at it wrong. Think of it as a percent increase in base resistance for a given increase in temperature. The formula for calculating increase is truly R*(1 + TCR *T), T being temperature increase in C, so it is a % rather than a value of ohms.
In your example, using 1 ohm coils, each coil goes from 1 to 1.2, the parallel circuit from 0.5 to 0.6. The increase in resistance is 20% each way, and that's what the chip is reading. The base resistance is important. You can have 5 or 20 wraps with the same wire for vastly different resistances, yet the resistance will still increase 20% when it reaches temperature no matter which coil it is. The chips usually have a junction to read ambient temperature with the coil at rest so it knows the starting point.
The difficulty with parallel coils is simply connection issues, usually when two coil leads are under the same screw. It'll still control temperature, but the two coils will be at different temperatures (the average will be the temperature setpoint) since one coil or the other will have a higher resistance at that connection.

 

[McDudeson]

Oh, I can tell you're wrapped around the axle on this a bit. My head spun a bit, too. But you are looking at it wrong. Think of it as a percent increase in base resistance for a given increase in temperature. The formula for calculating increase is truly R*(1 + TCR *T), T being temperature increase in C, so it is a % rather than a value of ohms.
In your example, using 1 ohm coils, each coil goes from 1 to 1.2, the parallel circuit from 0.5 to 0.6. The increase in resistance is 20% each way, and that's what the chip is reading. The base resistance is important. You can have 5 or 20 wraps with the same wire for vastly different resistances, yet the resistance will still increase 20% when it reaches temperature no matter which coil it is. The chips usually have a junction to read ambient temperature with the coil at rest so it knows the starting point.
The difficulty with parallel coils is simply connection issues, usually when two coil leads are under the same screw. It'll still control temperature, but the two coils will be at different temperatures (the average will be the temperature setpoint) since one coil or the other will have a higher resistance at that connection.

Holy S. I understand. Thank you. I've never seen it described as a percentage before. My explanation was the only reason I could think of to explain why my coils glowed at the recommended 5250 and operated perfectly at a lower tcr. Again, thanks for taking the time.

 

[Flavored]

My pleasure.

 

[BigEgo]

The atomizer is a sub zero. The IPV5 does not have a program for Nife 70. I have to use the manual tcr setting.

As was said already, are you sure that your wire is NiFe70?

I'm at .12, 450 degrees and 60 joules. I've yet to completely unravel joules vs watts.

Watts and Joules are the same thing as far as our mods are concerned. Yihi uses Joules to avoid Evolv's variable wattage patents. It does the same thing, though.

I have to tell it what the appropriate tcr is because there is no program for NiFe (nifethal) 70. And yes, the resistance will increase the same. The difference is in how the mod reads the increase. If both coils in a parallel circuit increase by .1, the total circuit resistance increases by .05, thus throwing off the tcr curve.

The mod reads the resistance of all the coils and treats them as one. It isn't reading them "individually" (don't think that's even possible).

 

[McDudeson]

Nifethal 70, or alloy 120 as I've seen it. Listed tcr is 5250. Still dialing it in. Thanks for the watts-joules explanation. And yes the mod reads them as one, but the coils have two individual resistances that the mod reads as one. It makes more sense that the mod uses percentages as opposed to absolutes.