Sub Ohm Vaping? Pros/Cons/Why?

[Ryedan]

just looked again and the PD is the protected version. regardless still want to know the best safest ones for my brother. guessing the aw IMR 1600?

I plan on running .8ohm -1ohm in my mech and will most likely have my brother do the same.

I should have mentioned that, sorry. I have seen the protected version available once too, can't remember where now, but as far as I know they are not common. IMR or Panasonic's hybrid technology are considered safer for high drain vaping.

0.8 ohms at 4.0 V is 5.0 A. You will get more than that from any of the bigger IMR batteries as far as I know. Not sure about the small ones.

 

[Ryedan]

Well that settles it, some random person on the internet said it.

I would hardly call Shekinahsgroom 'some random person'

 

[Ryedan]

ICR protected cells (at least 18650 please), good ones with 2 or 3 mosfets on the protection board, not the cheaper single mosfet boards that would trip at 3 amps or so, sound like they should handle intermittent currents up to 5 or 6 amps. That should safely handle the 0.7 to 0.8 ohm subohmers without tripping out all the time (full charge trip on current limit), unless you are boosting output to above native cell voltage. Of course you have to put up with another 25 milliohms or so in the current path because of the Mosfets. Any good IMR 18650 should be able to handle 10 amps and cover the 0.5 ohm and above vapers.

Excellent review and appreciate your adding in more information Rocketman. I'm very interested in learning more about cell protection. Why are there multiple mosfets on some boards and how do they work together?

 

[fabricator4]

EDIT: fab4, maybe a resistor in SERIES with the coil?
A typical late night flub. happens to me all the time.

Yes, I flubbed it, thankyou. I've corrected the post.

One cheap method of measuring a resistance would be to connect the unknown in series with a known, highly accurate resistor, of approximately the same value as the unknown and measuring the voltage drop across each individually. With nearly the same meter readings on both, the meter would be used only as a transfer standard, eliminating almost all meter error.

Yes, you've got it figured perfectly

R1 = 220Ω high precision temperature stable resistor
R2 = unknown resistance

R2Ω = R2V/(R1V/R1Ω)

eg
11.4mV / (4.99V / 220Ω) = 0.50Ω

To eliminate errors from an unstable current source, two meters could be used simultaneously, readings recorded, the meters swapped, recorded and the values averaged. The ratio of the resistors would be the average voltage ratio.

Not really an issue; any cheap 5V PS should be stable enough to be able to take two readings. No point over complicating things.

Just wondering, is that what most subohmers use?

No, most would not remember doing that in high school physics so it might not occur to them. Plus it is a bit of fiddling - you have to have either a breadboard or a soldering iron, and a wired up 510 thread to screw your atty into.

I offered it as a solution because you seemed to be implying that you wanted accuracy to two decimal places, and there's just nothing that will do that for any reasonable cost.

Multimeters and other cheap devices are one decimal place, and at best +/- 0.1Ω due to circuit instability and internal resistance. They give you a good idea of the resistance, but like I said you seemed to be asking for more than that. eg you gave "0.47Ω" as an example of the they type of reading.

 

[fabricator4]

Remember what we're talking about here, a functioning subohm atomizer is being called the equivalent of a potentially damaging dead short. As far as modes of abnormal operation, the external short is the least dangerous and likely also the least damaging. Not the least reason for which is it's reversible.

No. No, what you said was:

External shorts are actually not really a big deal. Every lithium battery testing standard includes external short testing. External shorts are probably the mildest abnormal condition our batteries face, because they are an extension of the normal operation of the battery. None of the battery's operational design is bypassed or defeated by external shorting. Most of our high drain batteries can take dead shorting without even venting.

Don't make the issue into something you feel comfortable with arguing around in circles and taking my words out of context.

I've seen people who argue like this and their arguments are the most disgusting examples of prevarication just for the sake of small minded point scoring.

To say that shorting lithium batteries is not a big deal without even specifying which or what type of battery is terribly irresponsible, even criminal. I can't help wondering if it's actually malicious intent, shear bloody mindedness, or just plain dumb ignorance.

No they are not, if the battery vents, catches fire or explodes, it does not pass the test.

You don't seem to get the difference between safety features and tests of those features, and the behaviour we should be encouraging to promote battery safety. Just because there's a safety feature to protect the user from harm, it doesn't mean that we should encourage people to do the exact thing the safety feature is there for. If you wish to test these safety features by all means do so, but to suggest that it's fine to do so with such a sweeping statement without even specifying the battery chemistry or the possible consequences is just wrong.

I'm not telling "people" anything, I'm addressing a person who is ranting hysterically about short circuits. Unhinged misrepresentation does not help the cause of education.

That is a weak semantic argument. No you didn't instruct "people" (as apposed to dogs, cats, and chimpanzees I would presume) to do it, but you certainly told them it is fine to do so. Go and have real look at what you're telling people it's OK to do and compare it to the manufacturers safety warnings, information written by industry experts such as Isidor Buchmann, and batteries warnings issued on ECF.

We know quite well what the baseline risks of vaping are with regard to batteries. What I'm talking about here are non-operational-drain related risks, of which there are several. All of them are more likely to happen than a problem with a working subohm setup.

No, you just said "baseline risks of vaping", nothing to do with batteries; just yet another semantic argument to imply you meant something else. The resistance in question is 0.2Ω, again without any qualification of battery brand, type or chemistry. I shudder to think of what may happen if some newcomer reads what you wrote and somehow thought it was OK to do these things with the blue unprotected lithium cobalt batteries that came with their Chinese mod.

Do you think some kind of semantic argument would absolve the arguer of liability? What about the liability of ECF and other participants of this thread?

IMRs and other modern high drain batteries have internal resistances well under 0.1 ohm. There's a reason these batteries don't get hot firing .2 ohm loads and below.

You've got to be kidding. I'll give you that *some* batteries, when new, under ideal conditions and temperature, may just read 25% lower, say 75mΩ. It's neither here nor there, the battery is still going to get hot, and it's right on the limits of what is safe to with special high drain batteries, and even then only when they are new and have the original capacity they were designed for. You can be pretty sure that the battery is going to age quickly and that internal resistance will rise rapidly during use due to heat and over time due to aging.

Also note that this is a completely separate issue to "External shorts are actually not really a big deal" I can see how you could confuse the issue though, seeing as how 0.2 ohms nearly a dead short.

 

[dr g]

To say that shorting lithium batteries is not a big deal without even specifying which or what type of battery is terribly irresponsible, even criminal. I can't help wondering if it's actually malicious intent, shear bloody mindedness, or just plain dumb ignorance.

None of us have explicitly specified any particular battery, that's the point.

You don't seem to get the difference between safety features and tests of those features, and the behaviour we should be encouraging to promote battery safety. Just because there's a safety feature to protect the user from harm, it doesn't mean that we should encourage people to do the exact thing the safety feature is there for. If you wish to test these safety features by all means do so, but to suggest that it's fine to do so with such a sweeping statement without even specifying the battery chemistry or the possible consequences is just wrong.

No one encouraged anyone to short a battery, another point. This NOT shorting a battery. But even if someone DOES short a battery, it's not the end of the world. What the hysterical posters are doing is basically suggesting that every battery could blow someone's face off for no real reason. That is ignorant and not a good practice when the goal is ostensibly to educate.

That is a weak semantic argument. No you didn't instruct "people" (as apposed to dogs, cats, and chimpanzees I would presume) to do it, but you certainly told them it is fine to do so. Go and have real look at what you're telling people it's OK to do and compare it to the manufacturers safety warnings, information written by industry experts such as Isidor Buchmann, and batteries warnings issued on ECF.

Did nothing of the short. Your relying on fallacious arguments is self-defeating.

No, you just said "baseline risks of vaping", nothing to do with batteries; just yet another semantic argument to imply you meant something else.

I explicitly clarified what I meant, no implication. To continue to argue otherwise is strawmanning.

The resistance in question is 0.2Ω, again without any qualification of battery brand, type or chemistry.

Again, that's the point, the poster did not take into account the battery. There are batteries that can handle that.

I shudder to think of what may happen if some newcomer reads what you wrote and somehow thought it was OK to do these things with the blue unprotected lithium cobalt batteries that came with their Chinese mod.

Then stop making excuses for unhinged ranters who are more interested in insulting subohm vapers than putting real information forward.

You've got to be kidding. I'll give you that *some* batteries, when new, under ideal conditions and temperature, may just read 25% lower, say 75mΩ. It's neither here nor there, the battery is still going to get hot, and it's right on the limits of what is safe to with special high drain batteries, and even then only when they are new and have the original capacity they were designed for. You can be pretty sure that the battery is going to age quickly and that internal resistance will rise rapidly during use due to heat and over time due to aging.

Here are some calculated internal resistances from common high drain batteries, including the types people use for deep subohm:
Torchy the Battery Boy: IMR "safe chemistry" batteries
And of course these tests which have been around for a long time have internal resistances: http://lygte-info.dk/review/batteries2012/Common18650IndividualTest UK.html

So, you're wrong and you need to readjust your thinking. People can indeed do .2 ohm safely, it is absolutely not equivalent to a short, and it is completely counterproductive to go off ranting and calling these people names, which is what the poster did and is what I have a problem with.

 

[Papadragon]

I should have mentioned that, sorry. I have seen the protected version available once too, can't remember where now, but as far as I know they are not common. IMR or Panasonic's hybrid technology are considered safer for high drain vaping.

0.8 ohms at 4.0 V is 5.0 A. You will get more than that from any of the bigger IMR batteries as far as I know. Not sure about the small ones.

The aw imr 18650 2000 mha is 10 amp the 1600 is 15 amp 18350 is 7 amp so .8 ohms will work fine on the 18350 other batty info efest and eh 18350 are 6 amps so .8 will also be fine but 7amp is better than 6

 

[vjc0628]

I get better battery life with sub ohm, 5 sec drag vs a 13 sec drag on a higher ohm setup. I also vape less juice a day in a genny vs a clearo, larger cloud less i need to vape to get my nic fix.

If you haven't done sub ohm don't post about something you have no clue about. Just sayin

1st the whole purpose to post something like this is to find understanding
That's why Im looking at this thread as I am looking at new devices
just saying

2nd your the 1st person ive ever seen said the vape less juice on a genny
look at any thread about how many ml's vaped per day or in the Rebuildables section
Just saying

 

[Papadragon]

Yes this is true less is more he might have not lowered his nic as most sub ohm vapers do so he could be useing less ask before you assume you can off as rude to me when I read this post vjc0628

 

[vjc0628]

Yes this is true less is more he might have not lowered his nic as most sub ohm vapers do so he could be useing less ask before you assume you can off as rude to me when I read this post vjc0628

I don't care

bottom line some one came here for answers That what this forum is about

when some one comes off with this arrogant response I take offence period

2ndly he may be using less

but most don't I see the posts most people claim the genny's to be juice hog's

to make that statement in the way that he did was to say the op was ignorant and had no right to speak

I take offense to that

 

[vjc0628]

Yes this is true less is more he might have not lowered his nic as most sub ohm vapers do so he could be useing less ask before you assume you can off as rude to me when I read this post vjc0628

And personally I am glad the op started this thread
I have found much of the info I was looking for
as I have been thinking about getting a mech for a genny I recently bought

 

[dr g]

k thanks. I used it a good amount yesterday and today and keep checking the charge and heat and it is now a little over 4v and hasnt felt hot at all whenever I check it. seems fine. will probably still grab some aw 1600mah IMR's

Note that some sellers, like Enerpower, take a NCR18650PD and put their own protection board on it, so it lowers performance a bit but adds protection. So ... it depends exactly what you are looking at.

 

[Zak Rabbit]

Thank you, Dr.g for making this thread read like one in the "outside" forum.

Sent via the guys that made Star Trek low tech.

 

[The Ocelot]

...To continue to argue otherwise is strawmanning.

One more time: "Straw Man" is a noun. "Strawmanning" isn't a word and it's use in this context appears to ignores the poster's actual position and substitute a misrepresented version of that position. If you don't understand something or have the wrong idea about it, your entire understanding of the system can be invalid.

On another thread you posted, "Assume every post has no intent other than to inform clearly and completely by default." Accusing other members of being "unhinged ranters" because you disagree with them is too much of a dramatic exaggeration to be considered having no intent other than to inform.

 

[Rocketman]

I think many folks don't fully understand how a protection circuit board works on a Li-ion cell.
Some may have gotten a bad taste in their mouth from the cheap protected cells that they probably overloaded and complained about being crap. There has been little change that I'm aware of in the basic circuit. An integrated circuit that has an overcharge comparator, an under charge comparator, and voltage sensors for overcurrent and short circuit detection, and control signals for the charge/discharge Mosfets. While the part numbers for the components may vary, with some being more reliable than others, the basic parameters are the same.

What separates most protected cells is the overcurrent 'trip point'. Cheap cells like the notorious Ultrafire will trip at 2.5 to 3.5 amps by design. Probably because the basic cell couldn't handle more than that. The trip point is a function of the voltage drop under load of the single back-to-back charge/discharge Mosfet. The 'On' resistance of this device is about 40 to 60 milliohms (circuit shown below). This resistance is in addition to the common 'cell internal resistance'. Adding these two resistances together makes the cell seem worse than it really is.
Remember that unprotected cells, whatever the chemistry, do not have this additional resistance. If you've looked at discharge graphs of different cells you will see this as an instantaneous voltage drop at the beginning of the discharge graph. 2 amps through a cell with a single Mosfet chip on the protection board will start off about 0.1 volts lower than an unprotected cell. What goes on later in the graph is a function of the cell itself.

Side note: Most discharge graphs set the horizontal scale for mah and compare the discharge capacity of various cells with a 3100 mah cell looking better than a 2600mah cell. When you set the horizontal scale for zero to 100% or some partial discharge point, you get to see internal cell performance not just mah. All cells start at the same point on the graph, all cells end at the same point. The shape of the curve tells you what is going on inside.

Moving up the line, there are cells that install a pair of these back-to-back Mosfets in 'parallel' to increase current handling and to cut the voltage drop in about half. So now, twice the current is needed to drop enough voltage through the Mosfets to trip the same controller chip. 6 to 7 amps through the parallel Mosfets drops the same voltage as 3 to 3.5 amps through a single Mosfet only because the resistance has been cut to 20 to 30 milliohms. Pretty much the same protection circuit, just an extra spot on the circuit board filled.

If you find a protected 18650 cell than can handle 8 to 9 amps without tripping the protection circuit, you will probably find all three Mosfet spots filled. Hopefully attached to a cell than can handle that kind of current.
The single and double Mosfet protected cells have gotten a bad rap for failing, tripping out, when most likely they were used outside of the intended design current.

For those into DIY modding (oh no, that means using a soldering iron ) there are add on circuit boards for 8 amp continuous drain currents (trip current about 12 amps) for single or parallel 18650 cells and 26650 cells. These use FOUR Mosfets in parallel. These even work well for high current IMR cells to add all the advantages of a protection circuit, with a lot less voltage drop.

Protection circuits don't work for free. They drop voltage, consume energy, and complicate selecting the correct cell for an application. More severe applications, like subohm RBAs, limit cell selection to only those designed to handle the extra current. In the day of the 2.4 ohm, 3.7 volt vaper, just about anything would work.

Have fun, be safe.

 

[sawtoothscream]

Note that some sellers, like Enerpower, take a NCR18650PD and put their own protection board on it, so it lowers performance a bit but adds protection. So ... it depends exactly what you are looking at.

performance wise im happy with. Battery last plenty long for my normal daily use and hits perfect right now. will have to grab a aw IMR and give that a go as well.

 

[Arnie H]

Arnie,
did you just like all 93 posts?
hehe

I'm liking the discussion and the banter (much of which is over my head technically) but I can't keep up with it. Too many posts. When I start a thread I like to show my appreciation for replies by likes.

Time for another thread that has to do with this subject, at least partially. I believe there may be some psychological reason for the cloud chasing, never statisfied thing. I will explain in the new thread.

 

[Rocketman]

Here's another one for you to 'like'

I'm sure everyone has experienced the occasional carto or atty that just didn't seem to function as well as the others, or maybe just can't seem to get this coil winding thing down to produce repeatable performance without going back over and over trying to get that perfect vape you had a couple of coils back. While coil form parameters like spacing, diameter, weird shapes may be your problem, variations in coil resistance may have you chasing your tail

If you can eliminate resistance from your variables you can focus on other aspects of coil making. I think this still falls in-topic, maybe as one of the 'cons' of subohm vaping.

For those that understand the theory of putting a resistive load on a battery supply, great.
For those that can wind pretty artistic coils, great.
But, being able to DIY correctly, repeatably, and not blame your juice for bad taste when it could be a coil winding error, may help with success. I posted a bunch of words about measurements. Maybe some read them, maybe some cared
But being able to baseline your coils will allow you to experiment with a higher chance of success.

The cost of good test equipment keeps many from setting up a proper DIY facility. Look for the 'cheap way out' whenever possible. Having access to commercial test equipment at work (if it doesn't get you fired), looking for bargain used equipment, or just finding components that can be used as reference material to compare your results to might be enough. Sacrificing one RBA head with a 1% resistor near your 'target value' would be one cheap way to standardize your coil resistance.

If you can't make it the next time, just like the last time, you will be wasting time and materials.
For those that haven't shopped around the electronic parts sources (just e-cig suppliers) here's a nice starting point.
http://www.digikey.com/product-detail/en/PAC300007507FAC000/PPC3D.75CT-ND/596389
A 0.75 ohm resistor, +/- 1%, 90ppm/C for $1.10. Get an assortment of resistors, some carbon film as low as 7 cents each, or
maybe even a higher powered load resistor to see what your mod puts out under load for $4.
A small bag gets shipped for about $2.30.

 

[Rocketman]

--------- I believe there may be some psychological reason for the cloud chasing, never satisfied thing.

Words like 'Quest', and 'Holy Grail' come to mind
The high voltage craze has pretty much topped out. Go over 8 volts or so and start getting the 'carto tingle',
Voltage becomes uncomfortable when your connector goes bad.

The only way to do more then would be multiple cartos (I tried 2 but not triples) or lower resistance.
To some it may really be the need to get enough vapor to convince themselves they don't really need tobacco.
For some that don't understand video lighting techniques, a way to get a better youtube cloud.
For whatever reason, it can be done safely.

 

[dr g]

Time for another thread that has to do with this subject, at least partially. I believe there may be some psychological reason for the cloud chasing, never statisfied thing. I will explain in the new thread.

"Cloud chasing" is a misnomer. Some people just like a lot of vapor. A lot of people who claim to believe "to each their own" sure have a hard time understanding that.