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Nervous as heck RTA

#1

Hello all. I am diving into new waters for me. I just purchased the WOTOFO Bravo RTA. I am nervous as all heck. I have been vaping for many years now and I always used the coils that came with the unit… The manufacturer provides coils we can use and are almost always 0.15 resistance and I run my mods at 320 degrees. I did just purchase some pre-made coils that are between
0.3 - 0.8 ohm and they are all SS. My question is, if I use the coils (which are all over 0.15 hom is there any danger is causing the battery to blow up? My unit is the WOTOFO Bravo RTA, Please help as I cannot use the new tanks until I get this resolved. Thank you all.

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#2

What mod u using

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#3

In theory, and in my experience…
Since you’re running in TC, you’re probably not using a mech mod, so all of the safety is built in to your mod. As long as your batteries are undamaged and wrapped properly, and your coils are installed properly, you shouldn’t have any issues. You might need to adjust your wattage and maybe temp if the vape is unsatisfactory. Ramp-up time could be different given the change in coil mass. Try it as-is first.

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#4

The resistance of the coils you a going to use should be higher or the same as the ones you have been using so they should put less/the same stress on the batteries.

I assume your quoted Ohm reading is per coil?

In which case when you put them into the dual coil RTA you total ohms will halve so
2x .3 coils should read around the .15 ohm mark
2x .8 coils should come out at around the .4 mark

While @Plunderdrum correctly states that the mod should handle most of the safety it is always good practice to make sure you are not going to overtax your batteries JIC you accidentally switch to bypass mode or something.

So with that in mind fit your coils and measure the resistance feed the details into an Ohms Law calculator.

The check your battery model with mooch to make sure the amp draw (from the calculator) isn’t crazy (it shouldn’t be) to do this put your battery model followed by the word mooch into google and look at his report on that battery eg. ‘sony vtc5a mooch’

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#5

I’m gonna double down with @woftam regarding Battery Mooch. Here is his youtube channel. https://www.youtube.com/channel/UCePHh3NMvu3rW2LFJeOWo-Q He is the authority on batteries as they relate to vaping.

is there any danger is causing the battery to blow up?

Simply, Yes. There is an assumption of risk with vaping and more so if you decide to build. Bad batteries, a bad mod, or both and things can go south in a hurry. There is a lot you can do to very much minimize the risk. I consider the risk to be negligible with knowledge of what you are doing but there is no perfectly safe.

Also ditto per @woftam regarding the wire wizard. https://www.steam-engine.org/wirewiz.html As you progress with the hobby indicators like heat flux, heat capacity, and coil mass will play a part in your building decisions as well as the resistance of the build.

I’m glad you’re nervous. If more people were nervous enough to educate themselves there would be fewer hyperbolic reports of people blowing off their faces on the godbox.

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#6

Even though regulated mods do have lots of safety features they don’t know which batteries you are using so bad things can still happen.
Find your battery here and look for CDR amp limit
then use the ohm calculator to see if you will go over your limit when vaping
what batteries are you using? how many of them? and what mod?
https://www.e-cigarette-forum.com/blog-entry/list-of-battery-tests.7436/#subs

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#7

What device and what batteries are you using?

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#8

Hello, thanks for replying so fast. I am using the wotufo BRAVO and my mod is the SMOK T-Priv. Thanks to all of you who replied so fast. Looks like I will have a lot to look up tomorrow as per all of your advise. Yes, I am nervous because I do hear about those people who just casually start building and not even care if what they are doing can be very dangerous. I must have lead the impression to all of you that I was looking for an absolute safe build but I know there is always an inherent danger when dealing with these values. Again, thank you all for replying so rapidly and with such great advise. God Bless and thank you.

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#9

For a given regulated wattage corresponding to the sensed coil(s) temperature, the (average) current (in Amperes) drawn from the battery power source will change with the square-root of the reciprocal of the total coil resistance (in Ohms) - so (for the same coil wattage, which may be somewhat different between devices to achieve a set regulated coil temperature), increasing coil resistance from 0.15 to 0.3 Ohms will decrease (average) current draw from the battery by ~29% - which is never a bad thing.

I presume that you mean Degrees Celsius [C] ? A temperature gradient exists between the coil surface temperature and the temperature of the nearby vaporizing juice. Thus, a 320 *C regulated coil temp does not translate directly to the temperature of the vaporizing juice nearby in the wicking material. There will exist some temperature reduction gradient (which is not a simple matter to model/predict).

The critical component of interest (Nicotine) “boils” at 247 *C. Thus, it will readily vaporize at temps lower than 247 *C. In the range of ~270 *C, PG decomposition into Formaldehyde increases significantly:

https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0169811.g002

… and VG begins to decompose into the known serious toxin Acrolein, in addition to Formaldehyde:

https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0169811.g003

… forming approximately 10 times higher levels of Formaldehyde than PG at the same temperatures:

It is noteworthy that the level of formaldehyde was about ten times higher from GL than from PG at the same temperature. Furthermore, the evolution of formaldehyde and acetaldehyde began at relatively lower temperatures (108 and 215°C, respectively), while the development of acrolein began at a relatively higher temperature (~270°C).

Source (published Jan, 2017):
A Device-Independent Evaluation of Carbonyl Emissions from Heated Electronic Cigarette Solvents

My basic approach is to increase Nicotine concentrations before increasing coil wattages - as some (relatively inexpensive, it is assumed) Nicotine that may possibly go unabsorbed does not compare to inhaling vaporized Formaldehyde (a known carcinogen), and Acrolein (present in tobacco smoke, and which is considered to represent ~85% of the cardio-vascular risks of combusting/inhaling tobacco). One downside of that approach is that (due to the higher “heat capacity” of higher resistance coils), one must as a result wait a bit longer for (what is an initially cold) coil to reach an equilibrium temperature.

.

While not much of an issue with user-controlled drip-atomizing (where juice is fully consumed in short order), in tank reservoir situations, the use of coil powers less than ~ 8 Watts (producing lower, safer coil temperatures) gives rise to an issue of the inhaled vapor (in addition to Nicotine) being composed largely of PG (which has a much lower decomposition temp of ~188 *C than the decomposition temp of VG at ~290 *C), producing steadily increasing concentrations of VG relative to PG in the remaining juice.

… at low power [ below ~ 4 Watts ] the aerosol produced by a 50/50 PG/VG liquid solution is composed almost entirely of PG, the more volatile component of the solution. … the evaporation rate of each species is proportional to the product of its intrinsic vapor pressure and its mole fraction in the liquid phase. Because the vapor pressure of PG is much greater than that of VG, vapors evaporating from a 50/50 PG/VG solution must be composed mainly of PG. However, as power was increased … the composition shifted towards that of the parent liquid, i.e., towards a 50/50 PG/VG composition. … a liquid composed of 7/93 PG/VG is required to produce an aerosol of 50/50 PG/VG composition. In other words, at the higher power conditions, the local liquid composition in vicinity of the coil must differ greatly from the 50/50 PG/VG parent liquid found in the tank reservoir. These observations point to the conclusion that resistance to species transport by diffusion within the wick gives rise to a concentration gradient between the tank and heated zone.

Source (published Nov, 2016):
Transport phenomena governing nicotine emissions from electronic cigarettes: model formulation and experimental investigation

Any increasing concentrations of VG relative to PG (in tanks) seems a good reason to limit coil temps.

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#10

Why would you presume this? 320 Celsius = 608 degrees Fahrenheit. Well past the ignition point of cotton. Is this a common temperature setting in TC? Not being snarky, I’m not well versed in TC, so I’m asking in an inquisitive sense.

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#11

I wouldn’t think C° right off the bat, that’s extreme.

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#12

I hope you do not expect me to understand what the heck I just read ?? lol I am sorry but I do not understand what you are saying. My lord, what have I gotten myself into ??? lol

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#13

it is Fahrenheit not Celsius.

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#14

So can you please explain that in terms we all can grasp. I found your post very interesting and informative, but you lost me halfway through with all the tech talk.

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#15

Rex, let me know what your question(s) about the text are, and I can try to clarify specific statements.

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#16

Don’t sweat it, man. Some folks like to flex their physics degrees, it isn’t nearly that complicated in practice. Besides, lots of that was based off of a false assumption.

Use the common batteries for regulated mods, make sure your batteries are safely wrapped, coils installed properly and dial in your vape.

I do recommend reading up on all of the info mentioned before that one, but don’t let the heavy stuff scare you. I’d be much more worried if it was a mech mod.

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#17

Ok thank you

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#18

:nerd_face:

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#19

I am using the SMOK T-PRIV and using 18650 3.7v 2600 mah. Not sure of the manufacturer.

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#20

WHEW, glad to hear that. I thought I was going to have to go to college just to learn how to make a coil…

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