Temperature coefficient of resistance and temperature factor of resistance

Quick start

Let's say you want to make a twisted coil with Ni200 and Kanthal for temperature limited vaping.

1. Under "Select wire(s)", click Add wire on the Kanthal and the Ni200.
2. The table "Temperature factors of resistance" is created.
3. Update the table with the resistance of each piece of wire. E.g. 0.15 for the Ni200 and 1.5 for the Kanthal. (There will be a way for you to directly insert the wire gauge with time, but for now you'll have to rely on the coil calculator to figure the resistance out.)
4. The column "Total R by temperature" will now show you the total resistance of your coil at various temperatures.
5. If you want to upload the profile to your DNA 200, copy the text in the "DNA 200 output" frame.

Results

The table shows you the calculated resistance for each wire, at different temperatures. You'll notice that as you change the resistance of each wire, the calculated resistance values are updated.

The row "Total R by temperature" will tell you the total resistance of your coil, after you have connected the selected wires in parallel.

The row "normalized TFR curve" is normalized so that the factor at 70 °F is always 1. These values are used in the DNA 200 output.

Downloading CSV

You can click the "Download CSV file" button to get a file for your DNA 200. This does not work in Microsoft Internet Explorer, due to security limitations, but it does work in most other browsers. If you need to use MSIE, you will have to do the following workaround:

• Make a new text file on your computer.
• Rename the extension of the text file from .txt to .csv.
• Copy the text from the DNA 200 output field to the clipboard.
• Paste it into your text file.
• Save the file to disk.

Sensitivity

Under "Sensitivity", you'll se a number like for instance 81 %. This means that in the temperature range typical to vaping, the resistance change will be 81 % of that of the resistance change would have been for a pure Ni200 coil. (A Ni200 coil will always score 100%.) A higher number means that your temperature control will be more accurate.

It is theoretically possible to score higher than 100 %, but first you'll have to find a coil material with a higher TCR than Ni200.

How low you can go while maintaining reasonably accurate temperature control, depends on your 510 connection, your atomizer, your building skills, and more.

Sources

Temperature points

The default values don't normally need to be changed, but if you want to, you can. There is no particular limit to how many points you can use (but the DNA 200 will accept a maximum of 8 points). Click the °F to the right of the input field to change to °C.

TFR and TCR

If the calculator has a resistance factor by temperature table for a particular coil material, it uses that.

When the selected temperature points don't correspond to the data points that are stored with the coil material, the calculator approximates them using linear interpolation.

If no table is present for a material, the calculator uses the TCR to calculate the resistances.

Thanks to

• Evolv for the suggestion to make this calculator, for the Ni200 TFR curve, and for the specification for the DNA 200 CSV.
• ECF user vapealone for the 316L and Ti1 TFR curves (forum thread).