kbriggs

In a two-cell configuration?

So it's measuring current and calculating P / I to get V instead of measuring resistance and calculating sqrt(P * R) to get V? That's interesting and would be a faster calculation. Now if you told me the chip did not have a sqrt() function built into it then what I'm asking for wouldn't be possible. But I doubt that's the case.

It may be pointless to you but not to me. Some people have no use for a tachometer in their car and some like to know where their red line is. I also use mech mods where I'm very cognizant of voltage and will usually build on a DNA device before moving it over. And yes, I was lumping the power equations in with Ohm's law since they are interconnected.

You are one not getting it. I know that DNA boards adjust voltage in real time if the resistance changes. And they do that by sampling the resistance at regular intervals and then recalculating the voltage it needs to send out via Ohm's Law. So what? The sampling rate is irrelevant. Wattage is not an electrical property, it's a calculation of power. The board doesn't send "watts" to the coil. It sends volts that are calculated from the desired watts and the measured resistance. And the resistance of Kanthal does not change in real time anyway, or at least not enough to even measure. The voltage that it settles on is perfectly predictable using Ohm's Law. I can see it directly on the screen if I fire and hold. But it reverts to 0.00 when I let go and thus cannot see it. I want to see it without firing. DNA boards are no different than other boards in how they calculate what voltage to send based on the wattage set in power mode. They all use Ohms Law.

On a Kanthal or Nichrome build in power mode, the voltage eventually gets to a steady output, specifically the square root of (watts * ohms) per Ohms Law. I just want to see that value cold before firing instead of just 0.00 like it shows now. I don't care that it may be off by 0.01 volts or so once the firing commences. I just want the extra bit of information so I can see what the eventual target is. This would be a trivial change to the firmware. It changes nothing in how the device operates and requires no UI changes.

Exactly.

By the way, VaporDNA is still advertising the Therion and all their other DNA167 devices as having a 7.4 volt capability, despite the fact I told them otherwise months ago.

Understood but it's handy to see where I'm at at any given time. I have dozens of mods, RTAs and RDAs and I'm swapping them around and trying different builds at different wattages with different airflow configurations, etc. Yeah, I can build lower, and do. I was just giving an example of where it has occurred before.

I have one particular dual clapton kanthal build (7-wrap 26g/36g, 0.52 ohm) in my Limitless Plus RDTA that I like at 85 watts. That's 6.65 volts and perfectly fine on my DNA 200 but a total fail on the 133 with its 6 volt limit.

That's a separate (although related) issue I addressed in the other topic. Here I'm asking for a simple feature change that would be trivial to implement in the firmware.

All mods, including DNAs, have a watt limit and a volt limit. For example, the 2-cell DNA 250s have a 167 watt limit and a 6.2 volt limit and whatever hits first is where it stops. So if I have 0.50 ohm build, I can't get anywhere near 167 watts because it'll hit the 6.2 volt limit at 76.88 watts. So it would be super handy if (1) the wattage indicator would stop there so I don't waste time going higher and (2) the volt readout that I have configured to show on the left side would give me the V = sqrt(W*R) calculation while idle (instead of 0.00 as it does now) so that I could see how close I'm getting to that 6.2 limit.

If it can't maintain the wattage I set then I want to know it, and if that reason is because it will exceed the voltage limit, I want to know that also. Then I can make a more informed decision and possibly change my build. This would be a simple coding change that gives a little more information to the user without affecting how the device operates.

They don't make one that will read my mod screen and show me the voltage as I'm adjusting the wattage up and down. And speaking of that. If while adjusting the wattage (on a DNA 167 mod, for example) and you happen to hit the 6.2 volt limit before hitting the 167 watt limit, the wattage indicator should stop incrementing right there because anything more will never get there. And if I'm wondering why my 167 watt device won't allow me to go any higher, I'll see the voltage indicator is reading 6.20 (instead of 0.00 as it does now) and I'll know.

Yes, but I don't want to fire without pulling air through as that risks charring the wick. It make take several seconds to settle in on the final voltage, depending on the profile. I want to see the target voltage as I'm adjusting the wattage instead of just showing 0.00. I'm not good at calculating the square root of W*R in my head and shouldn't have to lug around a calculator just for that. Yes, just like every other chip does it now and has for years.

It would be accurate for wattage mode, which is the only context I am referring to.