resistance ranges

[mattrix]

More important, Is that what 55 watts means?

Once you reach operating temperature, R=2.4 ohm, maintain 55 watts at the output. Then the temperature controller would need to be pulsing the output on/off.

Not sure I understand what you are Asking?

I always thought of the watts setting as an upper limit on the mods output.
So the mod would apply 55W until it reached operating temperature and then, presumably, less watts to maintain that temperature. Or even smarter start to ramp down the watts as the operating temperature is approached.

Your example seemed to suggest that when the mod is at its operating temperature the output will be at 55W

 

[GeorgeS]

The Second one is what I always thought was going on. From what I have Read and from others have said.

But I'll be the 1st to say that I'm not an Expert on TC

If you've ever used a portable DVM (Digital Volt Meter) the second one (computational limitation) makes sense. A 2V scale may resolve to 1/100V but a 20V scale may only resolve to 1/10V or even 1V.

So the resistance scales for VW and TC mode are likely to be different to handle the resolutions required for each mode.

Most mods have a ~3ohm limit because of output voltage in VW mode. VW mode does not require 1/10th, 1/100th, 1/1000th or 1/10,000th of a ohm accuracy or reading (or even 1/100,000th ohm) that some TC chipsets claim that they are able to measure/read.

 

[mattrix]

I have been looking at the VTC mini.
Joyetech do suggest that above the upper TC resistance limit the mod does drop into VW mode.
Also a firmware upgrade increased the upper limit from 1ohm to 1.5 ohm.
So it looks like the limits are just a function of the programming, and the max power range is a convenient place to put it.
Also I guess, given the materials used, you'd be hard pushed to get a coil above 1.5ohm.

 

[Imfallen_Angel]

Are TC resistance ranges rules or more like guidelines?

A mod will only achieve its maximum rated output over a range of resistances. I have some figures from a mod and it develops max Watt from 0.12 to 1.08 ohms.
It specifies a range of 0.1 to 1 ohms as its TC resistance range, almost the same as the max Watts range. Is this a coincidence?

Is the upper 1 ohm just arbitrarily chosen to match max power and it will provide TC at higher resistances or is it an enforced limit?

Physics....

Higher the resistance, the more you'd need a massive coil made of very fine wire that no standard deck could handle.

example: for 3ohms: 316L SS, 28 gauge, 3mm = 28 wraps

For TC to work right, this would need to be spaced... so I'd estimate a 40mm or larger deck.

The metal wouldn't be able to handle such a size easily, etc.

It has to do with the metal mass and multiple factors.

The chipsets are set for within a "standard" limit due to these.

The resistance is obtained by type of metal, the gauge of the wire, the number of wraps.

You can have 2 coils that are 0.5ohm, but one that would work fine at 60W, the other would melt at over 10W... so it's not simply about one thing (resistance), but several factors, which is what needs to be balanced when you build a deck.

 

[mattrix]

example: for 3ohms: 316L SS, 28 gauge, 3mm = 28 wraps

but 9 spaced turns of 30gauge SS316 is 1.57 ohms. Easily fit on a deck.

I just reread the thread and the question was really about enforcement, which the VTC does. I don't imagine it enforces the 3ohm VW limit.

 

[Imfallen_Angel]

but 9 spaced turns of 30gauge SS316 is 1.57 ohms. Easily fit on a deck.

I just reread the thread and the question was really about enforcement, which the VTC does. I don't imagine it enforces the 3ohm VW limit.

It's a question of the physics...between the voltage, and the metal used (and it's range), it's a safety limit that manufacturers have worked out.

More info here:

(extract)
Results


The minimum resistance you should use is typically determined by the PV's current (amp) limit. The maximum resistance is typically determined by the voltage limit. The median resistance is calculated by ignoring the power limit, and simply dividing the voltage limit by the current limit. The "sweet spot" is between the median and the maximum resistance. Keeping the resistance of your atomizer close to the "sweet spot" of your APV should give you a decent adjustment range (with most APVs), without necessarily pushing the mod to its limits.
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