Wow.. so where do I start? I appreciate all the responses.
MWA - Thanks for the direct reference. I read the entire document. Lots of good info, but I still do not see or more likely understand how this information can provide for an amp/temp chart for Kanthal wire similar to the Nichrome chart. (no snarkiness here, I just cant figure it out)
LucidAce - Spot on! 1st) Thanks for playing on my OCD and getting me starting on this obsession... 2nd) That guy in the video has the right concept but I am not sure if his thermocouple temp reader has the precision to determine actual wire temp...I could not see what he was actually doing with the probe so we dont know what he really measured. However, if he did do the same exact thing to both devices, then his data is probably comparable. I just dont know what we are comparing... Now if we had a precision IR temp reader with a 1mm spot resolution...that would be interesting for pulling together a data set.
Now back to this concept.....
I''ll expand upon original post and respond with the example in Studiovap's post. Primarily because his DID set up is so cool. That picture is truly a work of art. Both in form and function.
Ok, seems like you have no problems on juice wicking, so lets look at the math on the coil.
My calculations estimate that based upon your 180mm mesh, your wick hole is ~3.5mm. With your 28g wire and coil configuration, I estimate 1.9ohms with a coil wire length of 70mm. I am guessing by just looking at your picture...
With a 1.9 ohm coil:
4.2v, you are at 2.2 amps for total power input of 9.3 watts and more specifically .13 watts per mm
2.9v, you are at 1.5 amps for total power input of 4.4 watts and more specifically .06 watts per mm
(Source:
PV Web Apps) - Props to Tommcatt
Since you are using Nichrome (80?) we can refer to the Temperature look up table (
Resistance Wire.Com | Nickel Chrome, Nickel Copper, and Iron Chrome Aluminum Alloys from Stock)
At 2.2 amps, your operating wire temp is ~1400F/760C
At 1.5 amps, your operating wire temp wire is ~1050F/600C
These temps are estimates in an isolated air environment. So with juice/SS mesh as a heat sink and air flow for cooling, your actual wire temp is substantially less.
This makes sense given that the wire temp calc indicates a drop of ~30%. So in order to keep vapor production/taste at or near the 4.2v level, you need to adjust some other factor(s) to maintain wire temperature. The first factor is air flow. If we assume you are taking the same volume of inhale, but more slowly, you are reducing the cooling effect of airflow. The second factor is juice. The longer you have power going to coil and are vaporization juice, two things happen. You have less reserve juice availability in the wick and the hotter your SS mesh will become. Both of these effects will lower the nominal heat sink effect and thus raise effective wire temperature.
Now back to my point in the first post of this thread:
Based upon your set up, you are vaping starting at 4.2v and ending at 2.9v. and thus your corresponding power level will start at 9.3 watts, and will end at 4.4 watts.
That is quite a range, so what would one say is your "sweet spot" with this set up?
I assume you get some drop-off in vapor and taste as you deplete your batteries, but it sounds like you are compensating for the limitation of a mechanical mod. Cant' be watts, can't be volts nor ohms. These are fixed inputs into the equation, not the output. So it has to be a combination of your vape technique and the dynamic of your DID set-up.
So effectively you are balancing out all factors to optimize the vape, but the center of the universe for this balance is wire temperature along the coil.
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Variable Volt and more so Variable Watt devices are a great step in the right direction. Variable Watt devices more so because you can modulate volts on a fixed resistance circuit. But constant power "in" does not compensation for the other things going on in the atty that are dynamic. These all effect wire temperature. For example if you have a thick #500 SS mesh wick, your wire will run cooler than say a thin #325 wick. Right?....heat sink, juice delivery, surface area, etc..
So back to my original statement "Watts do not matter. Its all about wire temp." It was not meant to be all encompassing. We can discuss airflow dynamics, juice viscosity, lung capacity, whether you like your juice lukewarm, lightly toasted or full on roasted.
My intent here was to have a way to more effectively compare different user experience so we can learn and repeat. If your have a set up that works for you and you are using watts (volts) or in the case of mechanical mods (technique adjustments) that is great, because you have a way to balance all these factors to your satisfaction. But when I see posts on this forum and elsewhere that they have a "sweet spot" defined by watts (or volts), it really is meaningless for the reader. The dynamic variables will always changes and never permit replication. More so for modded devices.
What we do know is that too low wire temp..no vape. To high wire temp, burnt juice
