Hi everyone,
I have a V2.5 in the mail, but instead of picking up a temperature control mod from ineedhemp, I went for an SXK Nebula. Why? Well after reading this thread:
https://www.e-cigarette-forum.com/f...herm-nife30-coefficient-of-resistance.676506/
over on one of the biggest e-cigarette forums, I figured that having some control over the way the temperature control will function on my mod would be helpful.
The TLDR of the thread I linked is that (According to the thread author) mods calculate their temperature control via a property of the resistive element called Temperature Coefficient of Resistance (TCR for short) which is the amount said element (the ceramic donut in our case) raises in resistance " for a given temperature increase relative to its starting resistance."
While this is changing as time goes on, many if not most temperature control mods currently on the market have a TCR hard coded to suit Ni200 wire (though some support titanium, the upcoming DNA200 will support anything etc. etc.- the e-cig market moves fast). Matt posted earlier in the thread (if i understood it correctly) that he believes that the wire in these atties is nichrome. Given that we actually want to control the temperature of the cramic, and that said ceramic is of course heavily insulating the nichrome (heating element), and that nichrome is usually about 80% nickel (vs over 99% for ni200) I presume said hardcoded value is significantly higher than ideal. What i find curious is that nichrome's TCR is .0004, which is super low- i guess the insulation of the ceramic brings it up.
Thankfully, there are a few mods on the market that allow one to adjust the TCR. The best option (if one can get a hold of one at present) would be a DNA 200 mod, as this allows one to connect the mod to a computer and upload an actual TCR map/curve- I'm going to leave it at that as I haven't researched the chip much. However, these are hard to come by at present and tend to cost $160+.
Which brings us to the mod I have chosen- it has a chip made by a Chinese company known as Infinite or SXK, that has what they call a "Nickel Purity setting," which allows one to change the TCR (the setting ranges from 10 to 100- Ni200 has a TCR of .006, which corresponds to 60 on the chip.) The forum post i linked specifies which mods carry the chip in question, and has some purchasing options. Personally I opted for 3fvape, as those posting in the thread i linked reported that they have mods with the very latest version of the chip (earlier ones were reading the initial resistance of atomizers a bit low- but they still work great according to those in the thread and various e-cig youtube reviewers)
I've noticed people mentioning issues with their mod kicking out of temperature control mode. With this chip you turn temperature control on and off yourself- so i don't believe that's even possible for it.
I also noticed people mentioning that their atomizer's resistance doesen't rise when they heat it. It has been my personal experience with a ceramic donut atomizer from another source... i mean company
, that they can "break in" if you will (start heating faster over time). There are a number of possible explanations for this, one being manufacturing differences (varying amounts of contact/pressure between the nichrome and ceramic across different atties causing better or worse heat transfer), but the other possible explanation here is oxidization of the outside of the nichrome (which i imagine would theoretically improve your contact between it and the ceramic). I'm not studying physics in college like my best friend, and high school physics was like 6 or 7 years ago, but i suspect the TLDR here is if your atty's resistance isnt climbing mid-hit, it might just do so in time. Or if you give it more heat.
Now, I purchased a black one of these:
The SXK Nebula. I might have made a mistake though- there are 2 things- one i didn't notice until too late, one I forgot about. I forgot to find out if the chip has a cutoff time (a common safety feature for e-cig oriented mods) or how long said cutoff time is. At worst, this will mean quickly cycling the fire button every 10 seconds- not ideal, but i figure i can live with it, and worth it to me for an adjustable TCR. The second thing is specific to this mod (the cutoff time, if there is one, would be on all mods as it would be coded into the chip).
If you look at the above image, you might notice that the 510 connection is recessed into a circular cutout in the mod. This cutout is sized for the standard atomizer size for e-cig stuff- a review of the mod on youtube quoted it at 23.2mm in diameter (standard for atties in the e-cig world is 20mm).
I haven't been able to track down the dimensions of the ineedhemp 2.5 atty- if someone could let me know that would be extremely helpful.
But if the cutout is too small, that could of course be an issue. I ordered a 510 extension/adapter, but this is far from ideal given that temperature control relies on precise resistance measurements in real time- the manual of the device even says that if one's atty isn't screwed all the way in, temperature control won't work. So i suspect using a 510 adapter might degrade performance a bit (at minimum it will add resistance, which i will have to compensate for.
Thankfully, there are other mods with this chip that don't have their 510 connections sitting in a cutout.
In the future, I will probably buy a DNA200 mod, once they can be purchased in a size (and hopefully at a price) more suited to my purposes. At present, the mods coming out are packing enough LiPo batteries to push 200 watts- I certainly don't need that! So i'm waiting for a smaller device with less batteries to hit the market.
In the meantime, I will be experimenting with adjustable TCR temperature control via infinite's "Nickel Purity" chip on the 2.5 and 1, maybe 2 other ceramic donut atomizers on the market. Well, once my atomizer, mod, and batteries all arrive.
More to follow when everything shows and I test the setup.
I'm really hoping i don't have fitment issues- hopefully either the 2.5 is 23mm or less in diameter, or its 510 pin is long enough that i can get a good connection and airflow without the atty needing to get into the cutout. Otherwise, hopefully i can still get good performance with an adapter. We shall see:
Happy vaping!
Edit: BTW the Silver and Black versions of this mod are aluminum, while the gold is solid brass (and thus substantially heavier). I went black to keep things lightweight and less eye-catching (not often a legality issue where i live, but i like to keep a low profile), and because it was on sale ($5 off) for $48 shipped.
Another edit: for anyone whose mod has a Titanium setting, give it a try. If the heating wire is nichrome as Matt said, it should theoretically give more accurate results (IIRC Titanium's TCR is .0035- and if i understand all this correctly, the TCR of the 2.5 atty is definitely lower than .006)
