If I have read the basics in 101 and made it through 201 to this point, then the value of temperature control should be obvious. But just in case it's not let me sum it up, the proof is in the proceeding pages. Setting the temperature low enough will lower the vaping risks and WILL delay black gunk buildup. If I am still getting excessive or rapid black gunk buildup then either the vape temperature is too high (this includes bad build technique) for the eLiquid or I needed to change the eLiquid. My builds last for months when I run 100VG, no flavorings and 360F.
Temperature Control when it first came out was perhaps the most important evolutionary step in e-Cigarettes to date. I believe the known detriments associated with e-Cigarette vapor are caused by thermal decomposition of the e-Liquid ingredients. Much testing on flavorings still needs to be done but until then, they can be avoided altogether. In other words, using Temperature Control for me is not only wise, I consider it mandatory. As long as heating is the method used to produce vapor then it is only common sense that the peak temperatures of that heat must be controlled.
TP stands for Temperature Protect. It is a more appropriate term than TC though both are used interchangeably. The primary difference being the accuracy and stability of control.
So let us talk about vape temperature that is too high for eLiquid. Constant power delivered to the atomizer build as in a fixed/SV/VV/VW or improperly implemented, used and maintained TC mod can raise the temperature of the coil and wick too high if juice and air flow is not sufficient for the power setting. This is the typical condition with VV and VW mods. Temperature protection ensures that the power to the coil and wick is reduced when a set temperature is reached to avoid the coil and wick temperature from exceeding a preset level thereby reducing potentially dangerous temperature excursions that produce harmful byproducts as evidenced by black gunk build-up on the coil and wick.
I will discuss this in more detail below. How I construct the build coil makes a big difference in the risk, black gunk buildup and accuracy of the temperature protect/control. If the coil is spaced evenly the center wraps reach a much higher temperature than the outside wraps. The TC mod does not know one wrap form another. It looks at the overall resistance change. More change from the hotter wraps and less from the cooler wraps. This results in an average being read even though the peak temperatures in the middle wraps are much higher. Also imbalance in wicking where the center or one end gets less juice flow than the rest also causes temperature differences across the coil that the TC mod simply cannot know. All of these reasons are why I leave margin as discussed in Are eCigarettes Safe.
I can leave margin in two ways. First is to set the TC mod vaping temperature as low as possible to say 360F. Then I can lower power so temperature protect is never reached. I prefer to think of temperature control as a protection. Not a taste setting. A limit not to be reached but if it is, the mod will kick in and reduce power flowing to the atomizer build. Therefore I want to set power low enough that the entire length of draw including successive chain vapes never resuklts in the TC mod kicking into temperature protection. This is what I mean by sustaining. When I say such and such atty sustains 24W at 360F with 100VG, that is saying something. There is no thicker eLiquid than 100VG so this is the most stressing. 360F is very low and is also very stressing. And temperature protect never kicks in. In other words the TC mod doesn't think 360F has been reached. In other words, low risk. I also prefer the vape experience using this method because when TP does kick in, the vapor production within a draw is erratic. Just set power just under the point where TP kicks in and I am also rewarded with a more even better flavor density draw.
So four things to remember:
eLiquid ingredients are the biggest and most important risk factor creating black gunk.
Build technique for coil and wick to attain even heating and eLiquid/wick saturation across all wraps.
Temperature setting needs to be as low as possible leaving as much margin as possible.
Power setting adjusted to under the threshold where TP kicks in.
If I follow those four techniques I am rewarded with a less risk and better vape experience. Temperature control is just one of these techniques albeit an important one.
There are two primary TP devices on the market at the time of this writing, those based on the Temperature Coefficient of Resistance (TCR) property of metals and Electrical Ping Timing (EPT). I will discuss both in turn starting with the first to enter the market, the DNA-40 from Evolv Vapor out of Ashtabula, Ohio.
The Evolv DNA-40 board with patented power regulation and temperature protection, reverse battery protection, short circuit atty protection and soft limiting is shown above. This board is what provides power to the atomizer heating element also known as the coil that vaporizers the e-Liquid. To accomplish the temperature protection on the DNA-40, the coils must be made of nickel. Not Titanium, not Nichrome and not Kanthal. This is because the DNA-40 calculates the coil temperature based on measuring the coilís resistance over time and the TCR specific to Nickel. The TCR of Nichrome, Kanthal and Titanium is much lower and the DNA-40 temperature protect will not work correctly. In the case of Nichrome and Kanthal the DNA-40 will revert to normal power regulation mode without temperature protection. Even with Titanium, just lowering the temperature still results in inaccuracy as the TCR is lower.
In the case of Titanium wire, the DNA-40 will remain in temperature protection mode however that comes at the expense of three things all representing greater risk to the vaper which is the opposite intent. Because the TCR is much lower, the temperature set will have to be about half of that desired. If I wanted 450F, then I would have to set the DNA-40 to 225F. Secondly the resolution of the resistance measurement will be halved affecting overshoot and undershoot for the ramp up and protect functions. Lastly, while Titanium is used in implants, it is not entirely safe. Metals are discussed on Are eCigarettes Safe? page.
Though all wire regardless of what kind and where it is made needs to be thoroughly washed and scrubbed as it has industrial lubricants on it. I have found that alcohol alone doesnít cut it in all instances. Some have reported that using dawn, simple green or acetone works. But I don't do that as a rule. I scrub it with ethanol and then using a DNA-40 set to my vape temp, I coil the atty without wick and energize it while blowing on the coil several times including wetting it with e-Liquid and blowing until there is no smoke vapor or smell. Now I have no way of knowing if this scientifically reduces the lubricant to whatever parts per million but there is no foul taste when I put the atty back together, fill it and vape it. But if I donít do this, there certainly is. In the future, maybe we will see Ni200 available that has already been cleaned. Tempered Ni200 is a lot easier to work with as itís stiffness is closer to Kanthal.
With power regulation and temperature protection, I can concentrate on my coil builds and wicking techniques to maximize surface area and juice flow without having to worry about burning my juice and all that implies. And even though Kanthal versus nickel is apples and oranges, I find it humorous that Iíll be sub-ohming for safety. Nickel wire is sometimes called non-resistance wire. Although all wire has resistance. Nickel wire just has lower resistance than Kanthal. A typical Kanthal coil is between 1 and 2 ohms. So called sub-ohmers would try for less than an ohm, say like .3 or .5 ohms. But that could lead to high peak temperatures and acrolein production without TP so they really have to know what they are doing. But now with the DNA-40 needing Ni200 wire, typical coils are .1 to .3 ohms. I have even had some as low as .07 ohms though not as accurately controlled.
The reason it is humorous to me is that prior to temperature control, sub-ohming and cloud chasing meant risk of the coil attaining too high a temperature and producing acrolein and a lot of black gunk building up very quickly. The TP devices do not follow that higher risk trend. The DNA temperature protect is taking me in the right direction Ė lower risk I.E. more harm reduction. And it is for this very reason that I use them almost exclusively. It will keep me out of trouble.
Volume == Power || Taste == Temperature. Make no mistake, there are lots of bad science opinions out there about vaping and the DNA. But the truth is more power means more vapor and the temperature of the vapor determines taste. And what I realize now as has already been painfully pointed out in this site with rigor, more power without flowing more juice to the coil and/or without temperature protect set to the correct temperature for the specific eLiquid can produce harmful by-products, increase black gunk build-up and lessen coil/wick longevity. And some of those bad by-products due to high temperature excursions are not detectable by taste. Therefore, I say vaping without temperature protection is adding unnecessary risk. So much so that I have gave away all of my old non-TC mods, except a couple that I keep for memories sake.
Next came the SX350J board from Yihi also used in the SX Mini M=Class.
The SX350J board from YiHi Cigar offers reverse battery protection, output short protection, low resistance protection, battery low voltage protection, temperature overheat protection for the board and temperature protection. It works the same way as the DNA-40 in that it is built to use the TCR of Nickel. There are two primary differences with the SX350J. First it does not have a resistance refinement mode after 10 minutes and does not try to automatically keep up with new atty attachments. I have to manually tell it to reset the base resistance setting by holding down the plus and minus buttons at the same time. Secondly the SX350J uses Joules terminology instead of Watts. However it acts the same as the DNA-40 Watts terminology. The biggest advantage the SX350J has is its ability to be upgraded with software releases.
If I set something to 18 Joules then I expect it to output 18J and that's it. If I set it to 18J and fired for 1 second then that would be 18W for one second. If I set it to 18J and fired for 18s then that would be 1W for all 18s. But to do that it would have to have ESP to know how long my vape was going to be or I would have to set the vape time or it would have to assume a time and/or power ramp which of course I would not like. Forget about it. It doesn't do any of that. Just think of the Joules setting as Watts as it assumes per second, 18W for each second or 18J every second firing continuously as long as the button is pressed and it doesn't hit the TP limit. So even though it is set to 18J if I fire for 10s it outputs 18W every second for a total of 180Joules assuming it doesn't hit the TP limit and even though it is set to only 18J. In other words, it operates just like a DNA set to 18W.
The SX350J does have four selectable firing profiles called Powerful+, Powerful, Standard and Soft. I prefer the Standard and Soft. These firing profiles determine how many Watts are output over time for a given setting. In Soft the power starts lower and ramps up to the setting. In standard the power is constant. In powerful or powerful+ the power starts higher than set and ramps down. Builds that use heavy gauge wire and have more thermal mass, in other words takes longer to get to temperature may benefit from the powerful and powerful+ settings. Using 28 and 30 gauge Ni200 I find standard and soft provide a vape experience I like. On powerful+ and power settings, the vape gets to hot and in some cases can taste burnt.
The only issue I am aware of with the SX350J is a small software glitch where the temperature in the display shows a random value after setting the temperature limit and exiting the menu but displays the correct value as soon as the fire button is pressed. A simple refresh display issue. Iím sure Yihi will fix this in a subsequent SW update.
In use I prefer the simplicity of the SX350J over the DNA-40. It is not trying to automatically determine what I am doing nor does it try to refine the resistance reading throwing my vape experience off. The ability to manually set the base resistance instead of a computer program trying and sometimes failing to automatically determine my actions avoids mistakes. With that said, the DNA-40 under normal use is a great board and almost always interprets correctly. I canít go wrong with either one.
Then Evolv released the DNA-200. It allows the use of any wire that has an appreciable TCR as long as the TCR curve is uploaded for the temperature protection feature to work.
It is not clear that anyone needs 200W for vaping. But it sure is fun. Bigger is better right? Well, the DNA-200 is a great board and yields fantastic vapes, even if I never take it past 24W. However, it introduces three primary benefits over the DNA-40:
1. The DNA-200 is software upgradeable like some others are, but not the DNA-40. The firmware and the PC software that interfaces with the DNA200 over USB are both upgradeable and provide access to many features that were hard coded in the DNA-40.
2. For the first time, a TP board has been released that I agree accurately supports other than Ni200 wire types. That is because the DNA-200 allows me to upload a TCR profile in a Comma Separated Value (CSV) format. The other wire types like Ti and SS can be very nonlinear so just setting a single TCR as is done in other TP mods is not good enough. Although I still believe Ni200 is most accurate for TP wire to use, other wire types are useful for certain atomizers.
3. The DNA-200 brings LiPo 3S battery technology to the forefront. This is because the DNA-200 has a built in balance charger. Meaning the LiPo pack can be charged just by connecting to the built-in, on-board USB port with a standard USB charger, even a computer without having to pull the battery pack out to charge with an external battery charger that supports balance charging. A 3S designation means there are 3 Li-Ion batteries in series and cannot be charged correctly without a balance charger that gives access to the third cell or the cell in the middle. Simply charging from the two ends can be dangerous. Also LiPo packs run at three times the voltage so a 3S pack will need a third the current through each cell of a single 18650 cell would have to provide. The size of the cells in a LiPo pack can be larger or smaller than an 18650. The tradeoff is how big a mod I want versus how long I want it to last vaping without recharge. I find a 2200maH LiPo at nearly 30 watt hours capacity will last for two days easy versus a single 10 watt hour 18650 OR 900maH LiPo for maybe a day. The 2200 fits with the DNA-200 in a Hammond 1550B box which I find comfortable albeit a lot larger and a lot heavier than a typical single 18650 DNA40 or 900maH DNA200.
The downside of the DNA-200 is that it is a physically larger board and costs more. But the good news is, it is free of the issues that people had with the early DNA-40 i.e. screen glitches, battery indicator, etc. although DIY Mods based on metal enclosures have had issues with failed boards.
The good news is there are several DNA200 based mods with very different looks. Below is the Blacksmith diamond plate and Hotcig DX200 as examples.
Hohm Tech has released the first ever Kanthal Temperature Limiting mod called the Hohm Wrecker G2 shown below that uses EPT.
It is the most versatile mod I have used supporting virtually any wire in temperature control with the exception of Kanthal. With Kanthal wire the Hohm Wrecker G2 supports temperature limiting. The DNA200 cannot limit Kanthal. But in that mode the G2 is not accurate nor repeatable and requires a lot of fiddling every time I use it. But Kanthal limiting does work. While the DNA200 supports the upload of TCR curves, the G2 allows setting of what they call the Flag Ship Killer (FSK) ďcurveĒ percentage. I canít call the entering of a single number a curve and the FSK moniker comes from the chip manufacturer. But the FSK setting allows use of any wire type by adjusting just one number on the mod. No need to upload files or interface with a PC. So the DNA200 is still king of the TC boards and is the most accurate supporting an uploadable curve, but the G2 has great promise.
I think the best explanation of how the G2 works came in the form of a reply to Phil Busardo shown below:
ď1. EPT: Electrical Ping Timing - As the coils are heated, it is pinged) just like using the internet or when an officer using radar gun). The amount of time it takes for it to get from point A (starting line) to point B (finish line), determines a value. As metal gets hotter, the ping timing changes (in case of the radar gun, means I am travelling at X value speed).
2. Psycoil - this feature is designed to read the gauge wire(s) within a build. It does this by reading the volume and level of current applied to coils. It takes the collective fluctuation of volts/watts to the 1000th position, and pools this information together and compared to EPT values. This results in delivering precise volt/watts to the 1000th position. Future updates will further fine tune and go to 10,000th position of accuracy.
3. Ohm H/L Spread - using resistance spread (basic values of ohm change as metal heats). This spread is calibrated to pull back once coil(s) achieve any value outside of ohm spread as a safety measure to reduce risk of cotton burn.
All 3 values are used to determine and evaluate temperature and aim to prevent cotton burn. Kanthal is without a doubt the most complex of them due to its tremendous sensitivity, but very doable. We'll continue improvements as time progresses.Ē
The EPT that the G2 uses is very different from a TCR based device like the DNA200. And that is where Kanthal temperature limiting is being done as the TCR of Kanthal is an order of magnitude lower than the other wire types. But I canít call it temperature control, not yet. It has to be repeatable, stable and to the point where I can enter a set temperature and be assured it vapes at that temperature. Hopefully Hohm Tech will continue improving this as true temperature control with Kanthal would be impressive.
It appears in Kanthal or NiCr modes the G2 is using EPT as neither wire type has an appreciable TCR, In Ni, SS and Ti modes the G2 uses preprogrammed values or "curves" for TCR of those respective metals. In XXX mode, the G2 uses the FSK value as a function of TCR as I tested a ceramic tungsten heating element with a thermocouple and the XXX set to within 2 percent of the actual TCR resulted in the heating element temperature being within a few degrees of set temperature.
If Hohm Tech ever gets the Kanthal Temperature Control working accurately and reliably and they replace the weak plated brass 510 connector then I can recommend that to everyone. But as it is, I recommend the Hohm Wrecker G2 only to advanced vapers. For now, I would stick with a DNA200. Also Hohm Tech has announced another version coming in April/May. But I really think they need to fix the Kanthal temperature control on the G2 befo9re they do that. No one wants to get tied to a company that offers continuous promises but doesn't ever deliver.
June 2016 - I recently picked up a Hohm Tech Slice. It works just like the G2, uses a single cell 18650 or 26650. There are two downsides to it but the price is very attractive. First the battery cover lid will slide a tiny bit and second the board moves a tiny bit inside. But these are nuisances really. The settings needed for specific wire types in XXX mode are slightly different than the G2 and like the G2 it isn't completely accurate in SS, Ti or W modes and will not temperature control kanthal but it will limit. However the Slice is an ergonomic design at an attractive price point. I highly recommend pairing it with a Brillipower green 26650.
The Hohm Tech Hohm Wrecker G2 and Slice are the only TC mods I know of that uses EPT. There are many others that uses TCR, The newer devices have preset functions that I have to select for the different wire types and a few allow the user to input the actual TCR in some fashion.
A great recommendation for the EVOLV DNA75, specifically the HCIGAR VT75. Pictures and video coming soon. This is a great mod paired with a Brillipower 26650 and is my first choice for beginners.
These are my opinions about temperature protection based on hundreds of hours of use with many different attys and builds.
1. TP reduces but does not eliminate Black Gunk buildup.
2. TP helps prevent dry hits and bad chemicals but does not eliminate them totally.
3. TP is not temperature regulation.
Let us discuss these in more detail.
There are many factors that affect black gunk buildup. As long as the peak temperature the coil attains is lower than what the eLiquid needs to form black gunk then black gunk build up is reduced. I find my builds last longer until I get that burnt taste. The problem is two part. First, some flavorings carbonize at temperatures lower than the VG or PG base adequately vaporizes at and/or at a lower temperature than some people like (some people like hot vapes). For example sugar caramelizes at 340F. So any eLiquids with sugar in it should be vaped at less than that for adequate margin as coil temperatures can overshoot a bit until TP kicks in reducing power. Unfortunately, it wonít produce much if any vapor at that temperature. Note the biggest variable here is the flavoring. Some flavors can sustain a higher temperature before undergoing a chemical change. This area is one that I personally would love to see a lot more scientific research on. Secondly, the part of the coil wire that is in constant contact with liquid will stay at or below the boiling point of the liquid (whatever that is with all the flavor ingredients and a lot more research needs to be done) but the part of the coil wire that is exposed to air is susceptible to higher temperatures. Ideally we donít think temperature will vary that much from one side of the wire circumference to the other side. But it is possible and I believe does happen. And from what I have seen, the thicker the wire the more variation there is as evidenced by faster gunk buildup. Clapton wire (which is a wire spirally tight wrapped around a thicker core wire) builds gunk the fastest. Personally, I find my Ni200 builds with TP last up to three or four times longer than a comparable Kanthal build without TP in the same atty. Longer as determined by vape time or amount of eLiquid vaped, ie tank refills until I get that burnt taste due to the black gunk build up.
Wick can actually decompose even with TP if the temp is set too high. I also believe it is due partially to the TP device overshooting the set temperature slightly especially with the center wraps getting hotter. The bottom line is my wicking test proves the point that TP helps but doesnít eliminate the problems associated with dry hits if I continue to vape dry and don't leave margin or balance the coil wraps. It is very important that I stop vaping when I get a weak vape and take actions to correct the issue before continuing. It is also to leave myself margin. Leave 50-100F margin to the temperature at which all ingredients in my eLiquid break down. Since flavoring ingredients are not tested and little data is available, this means set the temperature as low as possible. Even though it is still unknown, it is the best chance of reducing the byproduct risk with flavorings.
It is important to note that TP is not temperature regulation. These devices do not hold the build temperature at a specific temperature. There is significant overshoot and undershoot. While the different boards employ different ramp functions the ďcontrolĒ is closer to a bang-bang function than critically damped regulation. Particularly the overshoots increase the black gunk buildup and risk of producing chemicals due to heat or peak temperatures. That is why I must set the power or energy level to a value that the build can sustain without hitting the TP limit for the duration of my draw including successive chain vape draws. By doing this, I give the device margin in its controllability which will reward me with less risk, longer lasting builds and better long term vape experience.
Other chips offering temperature protection are being released continually. And it is true that this is just the first step in the right direction for eCigarettes with additional innovation to come in the future.
But as it is today, the temperature protect with Ni200 wire can be troublesome for those that either do not understand low conductivity issues or those that donít want to deal with it. Yes TP APVs and Ni200 is picky. Very picky. Substandard kit will cause great aggravation. Keep in mind that substandard kit can also cause great harm. So if I take the time to understand the conductivity issues that TP will uncover in my attys and mod, then I will find there is no better vape and no better tool to uncover those problems and keep me safe. To do that, I have to realize and admit that I am part of the equation.
Within the safe range of temperatures for my specific eLiquid, there is still much I can do to ensure a better vape experience using a TC/TP APV. Let us look at some test cases I have personally experienced.
If I just set the TP APV to its maximum power and my atty can only take 12W before the temperature protect feature kicks in, I will get a weak vape. That is because when temperature protection kicks in, the TP APV drops power automatically to prevent the coil temperature from going beyond the set point. And the overshoot and undershoot will be large causing increased lag in the control. And when that happens, less to no vapor is produced resulting in a low vapor to air ratio. The atty has stopped producing vapor but I am still inhaling. In other words, resulting in a vape that is not as flavor packed and dense i.e. more air and less vaporized e-Liquid. In a word, weak.
If I set the power on the TP APV to 12 watts on that same atty and the TP APV supplies 12W throughout the entire length of my draw including subsequent draws if chain vaping, I will experience a much more flavor packed, dense, higher vapor to air ratio vape experience. In a word, yummy. The first thing I will notice is the display shows the power going above 12W for the first moments of the draw. That is because the TP APV ramps up the power to reduce the heat lag and aid in the production of vapor as quickly as possible without going too far. And if I watch the display under these conditions, I will see the temperature gradually increase but never get to the set point.
Let us say I use the same atty and increase the wattage to 14W. What I will see on the display as I inhale is the power being gradually reduced throughout the length of my draw as the temperature is getting closer to the set point. I might be thinking to myrself why doesnít the TP APV supply the correct amount of power to hold the temperature at the set point?
The answer is these TP APVs are NOT temperature regulated, it is temperature limited or protected. I may call limiting and protection a type of control but the connotation with control implies trying to maintain an output at a level in a damped manner. And that is not the case. And with good reason. If it attempted to regulate by temperature, the result would be erratic vapor production through the length of the draw. So at the beginning of the draw I will get a weak vape and then in the middle get yummy and by the end of the draw back to weak. And depending on the length of my draw, many excursions of weak and yummy in the same draw. The vape experience with temperature control/regulation would be wildly inconsistent.
That is why I totally disagree with those that believe there should be only one thing to adjust either temperature or power. I cannot achieve closed loop feedback control on temperature and have a satisfying vape experience with this TCR method of temperature ďcontrolĒ. I must set the temp I prefer and then also set power myself to the point that my build can sustain that power through the entire length of draw including successive draws if chain vaping so that temperature protect never kicks in. Perhaps future innovations will include a Kalman filter, or other type of learning, adaptive control that will automatically adjust the power down to where a build at any given point in time with draw and juice flow variability can be sustained. But that is a tall order. I do notice however that the DNA-200 vapes much smoother than the DNA-40 for whatever reason. And I do notice the SX350J vapes a lot more loosely ie allows a temperature band around the set point instead of bang bang around a specific temperature. There is just so much variability at any given instant in time, atty, mod and vaper. Future innovations may solve these issues. But I would not wait for that innovation. Much harm can be prevented myself switching to TP now and until that comes out.
Having used myself the eGo, eGo twist, VAMO, Seven-30, ACE, EVIC Supreme, SX-350 DIY mods, SX350J in the SX Mini M-class, VTC, SMY260 and the DNA-40 and 200, I can say without a doubt, the TP APVs are the best and easiest to use. And it showed me flaws in my build techniques and attys. Used properly, the TP APV is an excellent vaping tool.
The DNAs and SX350J are constantly reading the resistance of the atty. Though in temperature protect mode it will not show the real time resistance. With good reason, it is meaningless and potentially misleading to the operator. What it does show is the ďbaseĒ resistance of the atomizer. The base resistance is useful to the operator. The base resistance is the resistance of the atty when I first attach it. To get the temperature protect feature I have to use Ni200 which changes its resistance significantly when it heats up. While it may be interesting to read the resistance as it goes up and down as I vape, I canít make a decision to change anything with that information. Instead, the real time calculated coil temperature is displayed which is much more useful. By watching the temperature, I can see how far the temperature is staying below my set point. If the temperature of the coil is calculated to exceed the set point, the TP APVs back off the power. The DNA-200 has a PC software interface package that does allow I to view resistance real-time as well as data recording which is useful for generating my own CSV curves for the chosen wire.
The TP APVs will go to sleep after a while. When the DNA-40 wakes up, it will reread the base resistance. And if it detects a change in the base resistance from its last base resistance measurement (ie it knows I wasnít just recently vaping it) it will ask me if I put in a new coil (or atty). Similarly if I swap out the atty while the DNA is still awake, the DNA will detect that and ask I if it is a new coil. The SX350J simply assumes the same base resistance I manually set the last time. No fancy software trying to keep up with Ir activity. That is why I do not want to put an atty on these TP APVs that have just been vaped as the coil base resistance measurement will be off because of the residual coil temperature. Always make sure the atty is in equilibrium with the ambient air temperature before attaching it to a TP mod or manually setting the base resistance on an SX350J mod, even if the ambient air temperature is a freezer or an oven. That doesnít matter. What matters is if the coil is hotter than the APV due to recent vaping.
If I are using an RBA, I donít need a separate ohm meter. In fact any mod that shows I resistance eliminates the need for a meter. But the usefulness of the TP APV as a vaping tool doesnít end with showing I Ir builds base resistance.
The DNAs will drop out of temperature protect mode if it reads a resistance change while vaping (based on the base resistance it already read) that is not consistent with the TCR being used. This will result in the voltage setting being displayed instead of the temperature setting. The SX350J simply displays Dry Coil No Liquid and will not fire. When this happens, and I know I selected the correct wire, then there is a connectivity issue between the board and the coil. This issue can be a bad 510 connection between mod and atty, an incorrectly set or loose 510 adjustable center pin in the atty, weak spring loaded 510 center pin, corrosion, grime or juice in the 510 connection, loose center or ground post in the atty, intermittent contact coil build or loose coil leg connections. I have had all of these happen to me. On the DNAs, Ir first clue is the vape tastes bad as I are not usually watching the display. Then I look at the DNAs display and see it is showing voltage instead of temperature. On the SX350J it simply does not fire and when I look at the display and fire I will see the Dry Coil message. From there, it is a matter of rechecking all the connection points and screws to make sure they are clean and making good contact.
But wait, thereís more! Iíve verified Ir build is at the target base resistance I wanted, it hasnít dropped out of TP mode so Ir connections are good and now I are ready to use the TP APV as a test tool to improve Ir build technique. Adjust the power to where TP does NOT kick in through the entire length of Ir draw including successive draws if I chain vape. Then make a wicking/coil change and see if that build can sustain more or less power without TP kicking in. This is a great way to make build changes while measuring the effect - by how much power the build can sustain and not flood or leak. And I are doing this experimentation safely because the TP feature will limit the excursions into the temperature danger zone of cooking/cracking juice and getting nasty byproducts such as acrolein. That is why the TP APV is said to let I focus on Ir atty.
Make no mistake, there are attys that are temperature protect friendly and those that are not. First, dual parallel coils with Ni200 require a lot of wraps to get the total resistance near the recommended .2 ohms. I typically get .08 ohms. Basically each coil would need to be .4 ohms. And that is a tall order for Ni200. Other wire types such as SS are easy to get in a higher resistance range. Single coil attys are no problem to reach .2 ohms. However, there is good news for dual coils. The DNAs have soft limiting at .05 ohms and the SX350J will fire down to .05 ohms. I have several .07 to .1 ohm total resistance dual coil Ni200 builds that work marvelously with temperature protect. Secondly, the atty has to provide for very solid connections and very high (very low internal resistance) conductivity. The Kayfun V4 for example is an absolute no go without modification. The spring in the base of the KF V4 is a steel coil in that it has enough resistivity and TCR to get included in the temperature measurement. The reason for this is spring steel has a TCR of .005 and for nickel is .006. Removal of the spring and addition of a washer under the square nut and suddenly, the KF V4 becomes very TP friendly. As I go through the various attys I will illuminate the mods necessary to make them Ni200 friendly if I find they need it. The bottom line is they need very solid 510 and coil connections with great internal conductivity. I have yet to find an atty that I could not mod to make it Ni200 friendly. Itís just some require less to no modification at all to be Ni200 friendly.
Kangsxin, VTC, SX Mini M Class, Wadea and other TP or ďTCĒ devices have been released. I own the four listed and it is my opinion they are not as good as the DNA200. The M-Class is based on the SX350J but the inability to charge from the USB port (the USB is warranted for only 30 days and yes mine did go bad after the 30 days) makes it too much of a hassle to swap the 18650 battery vice simply plugging in a USB charge cable. The eVic VT is good but I prefer the vape experience of the Evolv tech.
Problems with TC can be caused by loose screws, bad 410 atomizer connection, incorrect settings, and atomizers that are not TC friendly like the Kayfun V4.Some atomizers use binding posts. These posts have a small hole through the side of the post perpendicular to the screw shank. The theory is that the screw tip will pinch the wire and make contact. In practice I find they will cut the soft Ni200 wire rather than bind it as their name implies. This is because the post screw holes are drilled and tapped way beyond the perpendicular wire through hole. I have cut snippets of stainless steel utility wire to put in those screw holes so the screws wonít cut the Ni200 wire. I have also rounded the screw points on a sharpening stone. But another way to ensure they donít cut Ir coil wire legs is to use a tougher wire. Thanks to the CSV capability of the DNA200, we can now use wire that is a lot more difficult for these dad blasted cut Ir nickel wire attys.
Now lets look at IR Camera testing of coils.
Clearly on a nearly contact coil the center two wraps reach a much higher temperature than the outer wraps.
Consider the image below.
TCR mods measure the total resistance, base and change. They do not know the temperature at every point on a wrap nor the temperature of each wrap. The same is true with contact coils on non-TC mods. The center wraps are reaching a higher temperature than the end wraps. This over temperature can be higher than the decomposition pont of one or more ingredients in Ir eLiquid. That is one of the reasons some people say TC doesn't change the black gunk buildup. I have to leave margin. Margin from the Set Temp to the Over Temp. If I space Ir coils more in the middle and leave as much margin as possible by vaping at a cooler set temp I can lower Ir risk of bad byproducts and decrease black gunk buildup. If I are running 100VG with no flavorings then do not vape at 500F. I have little margin to the temperature at which VG decomposes. If I ran at 500F then the center two wraps will exceed the decomposition temperature and bad byproducts as evidenced by black gunk buildup will result. And I need a lot of margin, so vape at around 360F or lower if I can. Keep as much margin as possible to reduce risk as much as possible. Even ceramic chips have hot spots. And we haven't mentioned hot legs as we will discuss in troubleshooting. Now throw PG and flavorings in the mix, especially those with chocolate and custards and the margin is nonexistant at any temperature that VG vaporizes at.
Now the big question is measuring the temperatures of each wrap. I can clearly see in the video and the graphs help illustrate generally what is going on but determining the actual temperature of each wrap is a little more tricky. I am still working on that. But by setting the DNA200 set temperature, I have found the minimum detectable temperature of the IR camera to be around 430F and with the DNA200 set temp at 500F the outside wraps are not visible with the IR camera. That is at least a 70F difference. They could be lower and the center wraps are certainly getting hotter as they are quite brighter. So for now, leave at least 100F and space the center wraps farther apart to reduce risk.
There are several components in the TC mod that are critical and some atomizers are TC friendly while others are not. We will discuss TC mod critical components and atomizer problems in troubleshooting and individually TC friendly atomizers in those pages, RTAs, Glassomizers and RDTAs.
There are a multitude of APV/mods out there. Donít be upset if I donít mention them all. The Provari for example is just solid as a rock. But they are not TC. And many that introduced novel features along the way or were more cost effective for beginners. But as we will find as we continue the journey there is one with a very important feature that outweighs all the others, TC. But to get there, we have to understand why. So letís talk about the heart of the APV. The electronics that make them smart. The regulator is based on a DC to DC converter.
The conservation of energy law applies to DC to DC converters. A DC to DC cannot invent energy. So how does it put out greater voltage than what the battery supplies it with? It converts current into voltage. Most DC to DC converters take the battery DC power and convert it into AC then rectify it back down to DC. And because of the law of conservation of energy we CAN apply Ohmís law. But we have to do so appropriately.
While we can apply Ohmís law to every component on the board and calculate through the entire circuit, it is easier to think of the DC to DC converter as a black box. Due to the law of conservation of energy we know that power lost due to losses (heat usually, can also be stray EMF) plus power out (delivered to the atty) must equal total power in. If the black box is putting out 9V and the atty resistance is 1 ohm then power output is 81W and the atty is drawing 9A. It follows therefore that the black box must be drawing 81W plus extra power to accommodate for losses from the battery. Letís assume the black box is 90% efficient. That means the losses are 10%. So the black box has to draw 110% of 81W or 89.1W from the battery. If the battery is at say 3.7 volts then it has to also supply 24 amps to the black box. In other words, the battery is supplying 3.7V and 24A so the APV can supply the atty with 9V and 9A. That is, if the black box, the DC to DC converter is capable of doing that. In other words its circuit is designed to do that.
Clearly then, 18650, 26650 and LiPo power packs have to be able to supply the appropriate amount of current for the power output desired. The top end 18650 batteries today can sustain 20 to 30 amps. But the average is more like 10 to 12 amps. So it is important to know what the regulator board needs by looking at its spec/data sheet.
Those specs are what separates the wheat from the chaff so to speak. One in particular claims to be 200W. But from its own data sheet its input current is limited to 30A and supply voltage can be as low as 5V. 5V at 30A is only 150W and at 94% efficiency is only 141W. But not so big a deal as Li-ion batteries are nominally 4.1V on a full charge so letís assume I have two Li-ion batteries in series for 6.4V at the end of their useful max current supply life (3.2V each), that yields 192W and with efficiency 181W. Not so bad, that is close to the 200W claim. Clearly on a full charge it is capable of delivering 200w.
Now letís look at the down convert. The datasheet claims it can down convert to .6V. But at .6V it can only output 24W. And from the datasheet, at .6V its efficiency is only 70.9%.
So, a mod that claims to be 200W really is only 17W at max down convert and 181W at the end of two Li-ion batteries in series at minimum useful charge.
Now I may be thinking ah but Iíll never use that .6V output. That is true but it is also true I donít need 200W to get more vapor than I can tolerate. With 200W I can fill a room with vapor and just poke Ir head in the door to take a couple breaths then close the door again. Regardless, this example emphasizes how I can check the claims of an APV against its data sheet. And the usefulness of matching what I need instead of raw power number chasing.
Today, Evolv has released the DNA75, 133 and 60. All chipsets that use the same type of temperature control, eScribe SW but very different battery configurations.
All the information contained in these pages are only the opinions of the author and the author is not an expert at anything.