Just my opinion here, but I think Sigelei obviously made a mistake with the tcr and then back peddled with the whole Fahrenheit vc Celsius spiel in an attempt to save face.
I really was trying to give them the benefit of the doubt at first and thought, "well maybe they are just trying to release a more accurate mod and stay competitive", but then they post that tool with all the numbers showing and a space missing for the number in the mod itself. Something isn't right there.
Then to add insult to injury they re-release it, call it the Fuchai 213, fix the issue and sell it for half the price. C'mon. Yeah, I have it working. Yes, I'm happy with it now, but Sigelei lost a whole lot of respect with all of this.
I'm with you as far as Sigelei making a mistake with the TCR, and it not being intentional. Why? I'm into electronics as a hobby, TCR/TFR is a worldwide standard/specification for resistors. It is the Temperature Coefficient of Resistance in Parts Per Million in degrees Celsius. Thus-- .000000 you have millionths... Or as steam engine shows.... TCR in vaping range 6000 ×10-6 = .006000
In electronics you need to know how much resistance change there will be under the expected operating temperatures, thus you spec the right parts, or possibly compensate for the differences....For Sigelei to say that their way is/was more accurate?!?!? Really? It's just math....So, they changed the method/formula/programmed in the Fuchai 213 so it can be half the cost... Sure....
TFR is pretty much the same BUT more accurate. It's more accurate as a materials TCR is not constant at all temperatures, thus you use a TFR curve to supply more numbers at specific temperatures for greater accuracy....
Ironic that Sigelei changed their TCR to be based on Fahrenheit, and still used Celsius for TFR, huh?
What's more ironic to me... Since Sigelei does NOT display live temperatures....they could take the easy, more efficient way out... no need for constant math to determine current temperature and display it on the screen, just uses more processor cycles, uses more battery, and more complicated....The could just use the standard math for TCR, base the starting temperature on room temperature(or 68F - 20C) use the resistance at that temperature, then take the temperature you input. From that calculate what the resistance SHOULD be at your required temperature, then adjust power output based on the expected resistance. No need for constant computations, processor cycles, etc... just monitor the resistance, and adjust power....
Maybe they do it this way....