Temperature Control - What is it and how does it work?

Hardware Hardware - Mods etc
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I checked the forum and while there is plenty of information about temperature control (TC) posted, it’s scattered around the forum and nothing really aimed at helping people understand it who may be new to the concept. So let’s take a look at what it is, how it works, and some basic information to help the newbie to understand TC and decide if it’s something they want to get involved with.

First, what is temperature control?

This term is actually not accurate. In order for temperature control to be an accurate description, the mod would need to be able to read actual temperature of the coil and make any adjustment needed to maintain the desired user temperature. It doesn’t work that way…at least not yet…but technology is always advancing so as of January 10, 2016, here’s what we have.

TC mods rely on programming that says with certain changes in resistance of the coil, the temperature will be x. Kanthal wire is not a good material for this as it’s resistance doesn’t change noticeably with temperature. However, Nickel (Ni), Titanium (Ti) and Stainless Steel (SS) - the currently used TC materials - do have this quality. They change resistance on a scale in correlation to their changing temperature. The graph below shows the resistance curve along the temperature band for Titanium, Grade 1 -

titaniumcurve.JPG787×188 9.37 KB

Because of this, the TC mod’s board is programmed with this information so that when these materials are used for heating coils, the mod can read these changes in resistance and make on-the-fly adjustments to the power being delivered to the coil in order to limit the temperature to what the user sets.

So, while TC is an inaccurate description, it’s the one being used in the e-cig industry. More accurately, it’s temperature limiting.

How does it work?

With a TC mod, when using a coil made of Ni, Ti or SS, the user will set the temperature limit and, in most cases, the wattage desired. For example the user may set a temperature limit of 450F and 50 watts. Unlike simple regulated mods which will deliver the watts set no matter what, the TC mod may or may not deliver the 50 watts set. That will depend on whether the coil gets hot enough so that it reaches the 450F set by the user. For argument’s sake, let’s say the 450F is reached using only 40 watts. That means the 40 watts is probably all the mod will ever use while the current coil is attached and the 450F limit is set. However, if the 50 watts is fully utilized yet the coil temperature only reaches 425F, then the desired 450F will not be reached unless the user raises the wattage set.

This is where technology may eventually change with TC mods, allowing the user to set a desired temperature and the mod would choose the wattage needed to reach that temperature. We’re not there yet. There are, however, some mods that only allow the user to set the temperature but not watts, as is the case with the SMOK xCube II which instead of having a user adjustment for watts, has 5 levels of power.

IMPORTANT In order for a TC mod to work properly, both atomizer and TC mod should be at room temperature when connecting the atomizer to the mod. This allows the mod to read the coil’s base resistance in order to accurately read changes in resistance.

Coils and Wire

In 2015, TC became all the rage. And rightfully so. With a properly functioning TC mod, gone are the days of dry hits, burnt cotton, and inconsistent vapes. And due to the proliferation of TC usage, many manufacturers of tanks jumped on the bandwagon and started putting out coils for their tanks using Ni, Ti, and or SS.

What may be more popular in the long run for TC enthusiasts is RDA and RTA coils. Users can purchase their wire of choice and build their own coils to be used in TC applications, This has been a game changer for many TC users. See the end of this article for good wire resources. Also, if you’re inclined to build your own coils here’s a good thread about prep and use of wire. It’s specifically talking about Ti wire but I believe it should apply to all wires.

As for building coils, there should be some attention given to resistance. Ni, Ti and SS offer far less resistance than Kanthal. this is especially true with Nickel which is so low-resistance it is nearly impossible to build dual Ni coils that will have resistance high enough for the TC mod to fire them. It may be wise to check out wires at Steam Engine and learn what your resistance will be before building your coils. That way you will know if your mod will fire it. Most mods have a maximum low ohm for coils between 0.06 and 1.0 ohms.

Mods

The saying “you get what you pay for” isn’t necessarily the case. There are many, many TC mods available on the market. Some expensive ones that are awesome, and some that are failures, some cheap ones that are junk and some that are great. The smart shopper will do his or her homework to make an informed decision before purchasing. Simply calling a mod a TC mod does NOT mean a favorable experience. Due to the fact that the technology is still relatively young, TC has plenty of room for improvement. Urgently feeling a need to compete, many mod manufacturers sort of haphazardly slapped some TC mods together quickly and rolled them out to the market. That said, as of today I can say that any DNA 200 device would rank at the top. Most Joyetech TC mods are good quality along with most Pioneer4You mods. Just do your homework.

As for what to look for - that’s another story. Early TC mods only had TC function for Ni wire. Then Ti came on board, then SS. As for which is better, well that’s for sure a personal opinion. Many people think Nickel is great, but I don’t like it. I’ve detected an undesirable taste from it. SS has a very narrow resistance change band and therefor is the most finicky wire and hardest to deal with. I prefer Ti wire, but again its a personal thing. Just make sure the mod you’re looking at supports the wire you want to use. Otherwise maybe just get one that supports them all. You may want to read this thread about TC mods.

Where to buy wire

My preferred place to buy Ti and SS is Unkamen Supply
Titanium I strongly recommnd Grade 1
Stainless Steel There are several grades of stainless. Do your homework and choose what’s right for you. I use 316L and 317L.

Lightning Vapes Sells Nickel wire as well as most others, so if you want a one-stop wire shop this may be fore you.

If you’re new to TC please don’t hesitate to ask questions. There are some very knowledgeable people here who can help guide you on anything from mods, to wire, to building coils, to wicking and everything in between.

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Wow! Thank you for this!! I’ve got a TC device but knew nothing about it and was afraid to even try! Very concise and crystal clear!!! I feel like I can give it a shot now☺️

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Excellent write up.

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Great stuff! You should share this link to /r/electronic_cigarette :slightly_smiling:

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I second this, great info and lots of people out there who havent any idea.

If you dont have a reddit account holler and ill post it for you.

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@daath and @Ken_O_Where you have my blessing to post this anywhere you like. I don’t do Reddit except as a reader.

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Might wanna add something about Nichrome vs Nickel.

Ni200 is the Nickel wire used for TC. Nichrome 80 (sometimes mis-abbreviated as Ni80) has a similar temp coefficient to Kanthal and so it is no good for TC.

I only mention this in case people see Nickel abbreviated “Ni” and then see Nichrome and get confused. There was even a post on Reddit where some guy was asking how to use Nichrome for TC after a brick and mortar shop sold him some when he went in asking for Nickel for TC. Not cool.

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Great post there! That’s one of the things that makes this forum worth coming back to - it’s people like @SthrnMixer here that know their stuff but keep helping newcomers along!

I’d like to add my two cents about the mods that have you set a temperature instead of wattage. First off, I have to admit that I was rather disappointed with temp control only being a cap to prevent burnt wicks. Later on I found the SMOK Treebox, which is IMO the best 75W TC mod I could find to date: it’s sturdy, it’s lightweight, it’s easy to dial in and it’s sexy, because it’s wood. :wink: But most importantly, you set a temp and the chip does the rest. It’s working rather well in my experience, haven’t tried the xCube mentioned above to compare though. It does give me a very consistant vape at a set level.
Just yesterday I found the Chieftain by Wotofo, which is meant to achieve and hold the temp you dial in in less than a second. And it’s 220W max - personally I doubt that number though, as you only have two 18650s, so maybe more like around 150W, but that’s still more than enough for me. It’s not here yet, but once it is, and given no one else does a little write up about it, I might let you know what my thoughts are.

Cheers! Keep it up and vape on! :smiley:

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You go right ahead and post it @daath. :smiley:

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Ok, done :slightly_smiling:

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Great stuff @SthrnMixer …& very timely! my first TC mod (RX200) arrived a couple of days ago. While I am coming to grips with it, this info will help me understand it much better. Thank you!
vT.

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Thank you for this @SthrnMixer :+1:

I am just now starting to explore DIY coils, RDA’s and RTA’s. I tried some clapton kanthal over the holidays in a Velocity and really enjoyed tinkering with it.

During my research, I decided to also try titanium due to reviews here on ELR. So now I have a Griffin and some 22awg Ti headed to the house and I’ve been pokin’ around looking up TC discussions. This is a great consolidated rescource you’ve made here, excellent work!

I feel like my natural progression in vaping has been placed in a hadron collider since I found ELR and the knowledge of this community! Thank you for reducing the arch of the learning curve on this :smiley:

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Great article @SthrnMixer

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This term is actually not accurate. In order for temperature control to be an accurate description, the mod would need to be able to read actual temperature of the coil and make any adjustment needed to maintain the desired user temperature. It doesn’t work that way…at least not yet…but technology is always advancing so as of January 10, 2016, here’s what we have.

TC mods rely on programming that says with certain changes in resistance of the coil, the temperature will be x. Kanthal wire is not a good material for this as it’s resistance doesn’t change noticeably with temperature. However, Nickel (Ni), Titanium (Ti) and Stainless Steel (SS) - the currently used TC materials - do have this quality. They change resistance on a scale in correlation to their changing temperature. The graph below shows the resistance curve along the temperature band for Titanium, Grade 1 -

You say these mods don’t read the temperature, but if you say that then I will say that a mercury thermometer doesn’t read temperature either (it reads the expansion of liquid mercury). I will say that a thermocouple (widely used in industry for temperature readings) doesn’t read temperature but only reads the change in voltage at a junction between two wires when heated or cooled. I will say an infrared thermometer doesn’t read temperature, but only reads the emissivity of an object.

So, as you can see, it makes no sense to say our mods aren’t reading temperature because if you say that then you’ll have to say that the aforementioned thermometers also don’t read temperature. Moreover, our mods use a principle of thermometry called a “resistance thermometer” or sometimes a “Resistance Temperature Detector” (RTD). These thermometers are widely used in scientific labs and industry when high accuracy is needed. Indeed a platinum RTD is used as the ISO standard for temperature calibration. How do they work? By reading the change in resistance of a wire (usually platinum or nickel). Hmm, sounds a lot like what our mods are doing.

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Well, technically it’s correct. It reads resistance changes and calculates temperature :slightly_smiling: And yes, similar things can be said about the other forms of measurement :slightly_smiling: But we’re splitting hairs here, right?

Speaking of - I wonder if platinum wire will be used for vaping :stuck_out_tongue_winking_eye: Or any of the other weird metals :smiley:

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Platinum can already be used on the DNA-200 if you don’t mind forking over the cash for very expensive wire and if you can fit a big enough coil in your atty. The problem with platinum is its resistivity is even lower than nickel’s. This sucks for vaping, but makes it fine for use in a thermometer where space isn’t limited. I believe the standard platinum RTD is 100 ohms at 0°C.

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Great Subject to do a tutorial on @SthrnMixer!

I have a question… what does locking in the ohms do? And should I be doing it? My gf says no, never again. But that is a different subject altogether.

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Thanks for the compliment - everyone.

To my understanding, Ohms Lock is for when your mod is jumping around reading the atty ohms. For example, when you first install the atomizer let’s say the mod reads 0.20 ohms. You take a puff and set the mod down. Come back 10 minutes later and now it’s reading 0.4 ohms. Ohms lock is a way to force the mod to see the same 0.2 ohms. The way most people use it is to lock the ohms when they installed the coil on the mod. However…

Why would ohms be jumping anyway, and is ohms lock a good practice? First, ohms changing (apart from normal changes during usage - i.e. the resistivity of the metal means ohms increases during heating) there are several things that could cause resistance fluctuations. Things like a loose or broken coil, bad wiring or solder joint, bad battery contact, poor 510 connection. Keep in mind that the resistance change from 0.2 to 0.4 ohms is only very slight in terms of actual resistance, but huge in terms of power delivery by the TC mod to achieve desired temperature.

In my opinion, ohms lock is something to get you by until you can sit down and diagnose a problem, not as a standard way of operation. Just like a donut spare is for getting you to a place where you can get a flat tire fixed. There is plenty of disagreement on the forums about this. Myy opinion is shared but there are others who feel it should be standard procedure to lock ohms. Truthfully, if the build is right then there should be zero reason for locking ohms. That said…

On my Joyetech eVic VT 60, it often runs cool. I don’t think the mod reads resistance correctly. So I will sometimes “trick” it into working better. I’ll install the coil and take a puff or two. If it’s anemic (and I’ve cranked up temp and power) then I’ll let it cool down, remove the atty and hit fire to clear the coil, reinstall and take a short puff. If it’s still anemic I quickly remove the atty and reinstall. If it jumps up around .02 ohms or so, I’ll lock that in and it vapes much better. That quick puff heated up the coil slightly and raised ohms a bit. So if a person were to need to lock ohms because they have a mod that doesn’t read ohms correctly, yet they want to use their mod, this would be a reason to use it regularly - with that mod.

Again, opinions on this varies and I’m no expert by any stretch, it’s just how I do it.

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Of course it makes sense. You need to understand that ohms do not equal temperature. All the mod can do is read ohms. It relies on 3 things to provide the best guess at temperature - 1. programming of the TCR, 2. reading the resistance change and 3. setting the baseline. And that baseline is the critical component which is why people are instructed to attach the atty to the mod when both are at room temperature. But what is room temperature? It’s as accurate is lunchtime. And it’s this pin the tail on the donkey approach at calibration that separates a TCM’s ability to read temperature from all the other sources you mentioned…giving it a margin of error that would be unacceptable to all these other devices as well, although for vaping it works exceptionally well. Besides, how accurate do you think it can be when it’s reading temperature and creating heat at the same time? No one cooks a roast with a meat thermometer.

Can we stick with the purpose of this thread? Helping people who do not have a basic understanding of temperature control. Lessons on electronics and thermodynamics would be better suited elsewhere.

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Working in calibrations myself, I like what he’s bringing to the table and hope he continues, if you don’t mind…he’s speaking my language, even if it is like a 2nd language to me at this point.

To continue with my findings, here in florida, where the temps aren’t as frigid as they are elsewhere…I think temps here MUST be on the threshold of the ambient temps these devices are looking for.
Indoors at 70°+ works flawlessly…step oustide, low 60s…knocked out of TC, repeatedly…I stand behind my previous statement, these devices wanna see 70 ambient…and I’m pretty certain this is why people keep getting kicked out of TC “for no reason, this device sucks!”…and no its NOT just one device I’m reading these complaints.