Lower than .20?

[Aviationrich]

I have two vtc4s and one vtc5 and I've been seeing that alot of people are going below the safe area for those batteries. One person told me he went to .07, when I did the calculation for that it's something like 56 amps! Those batteries only go to 30 amps, are they just carefree vapers, or am I missing something?

I've only been using mechs for a little more than a month, but I am wanting more than what I'm getting now, but I definitely want to be safe about it.

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[MorpheusPA]

You're going to get several different opinions on this one.

IMHO, if you're overstepping the maximum amperage capacity of the battery in a device that's near your mouth, this is just asking for trouble. While the burst output is frequently higher than the sustained, I don't ever recommend pushing it. The probability of failure becomes much higher.

That having been said, I also wouldn't push anywhere close to the rated output to increase the safety factor. On a 30 A max draw, I wouldn't dream of exceeding 15 A. That's extremely conservative, and I certainly don't expect that most people will go that far. However, my teeth are expensive, I've paid a lot to get them repaired, whitened, straightened, and kept pristine. I don't wish to damage them if I can avoid it...

 

[Baditude]

0.2 ohm is just 0.2 ohms from a dead short. A dead short causes batteries to go "hissssssssssssss" and get EXTREMELY HOT at the very least. At the very worst...



I don't care how many amps your battery has, a dead short will cause any battery to go into thermal runaway. People who make coils less than 0.4 ohm are taking for granted that their inexpensive (less than $50) ohm reader or digital multimeter is precise and accurate. Good luck with that belief. Unless you've tested your meter against a Fluke or similar meter you have no idea how accurate it is.

 

[Aviationrich]

I've been doing my builds at around .28, I did do one that was at .24, it didn't last long for me. I'm happy around .28 as much as I would like bigger clouds, I don't think I'd go lower than that. I'm going to try a thicker wire soon but I'm not wanting the super low stuff.

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[MorpheusPA]

I've been doing my builds at around .28, I did do one that was at .24, it didn't last long for me. I'm happy around .28 as much as I would like bigger clouds, I don't think I'd go lower than that. I'm going to try a thicker wire soon but I'm not wanting the super low stuff.

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Like Bad said, if your meter is good, that might work. In my case, that would mean my meter is actually reading the coil as around 0.6--and I know my accuracy is questionable.

For me, a poorer meter doesn't matter, my target is usually 1.8-2.0 Ω. It would require that my meter actually be broken to mis-read that too far!

 

[Aviationrich]

Is there a way to check the meters accuracy?

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[MorpheusPA]

Is there a way to check the meters accuracy?

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Only if you use a known-good meter to check, or use known-resistance (voltage, amperage) items to check your meter.

A very simple guesstimate at the low end can be made by touching your meter's probes together to get the base resistance. In my case, it's a hair over 0.3, but that shouldn't be considered "testing" your meter. Inaccuracies can be (and usually are) non-linear, and may have singularity points where it just all goes south, particularly on cheap meters near the boundaries of their measurement ability.

Testing a meter isn't permanent, either, and should be done periodically. Oxidization on your leads (or just a bit of gunk or oil) can mess up your readings pretty badly. Electronics age a little over time, batteries powering the device get weak, and so on.

Like any other precision instrument, it needs to be cared for properly to function properly--and most people (myself included) don't get anywhere near that.

 

[Ed_C]

I can see it now, the next big fad. Dead short vaping. Guaranteed to blow your mind!

 

[Ed_C]

Only if you use a known-good meter to check, or use known-resistance (voltage, amperage) items to check your meter.

A very simple guesstimate at the low end can be made by touching your meter's probes together to get the base resistance. In my case, it's a hair over 0.3, but that shouldn't be considered "testing" your meter. Inaccuracies can be (and usually are) non-linear, and may have singularity points where it just all goes south, particularly on cheap meters near the boundaries of their measurement ability.

Testing a meter isn't permanent, either, and should be done periodically. Oxidization on your leads (or just a bit of gunk or oil) can mess up your readings pretty badly. Electronics age a little over time, batteries powering the device get weak, and so on.

Like any other precision instrument, it needs to be cared for properly to function properly--and most people (myself included) don't get anywhere near that.

Often you read a post where someone says, that they got this cheap meter and it works great. I always want to ask, ......and how do you know it works great?

 

[MorpheusPA]

Often you read posts where someone says, that they got this cheap meter and it works great. I always want to ask, ......and how do you know it works great?

Hear, hear. You don't. It's easy to use, that's about the best that can be said.

I build electronics for funsies, so I have resistors around whose resistance I know within a given tolerance (for the best, that's a pretty tight tolerance as well). My meter's OK, good enough for my purposes, but I wouldn't bet my life on it.

Near-zero (say less than 3 ohm) readings are a whole other kettle of fish. One slightly off contact can really ruin your day there--if a 1,000 ohm resistor is measuring 1003, it doesn't matter. If a dead short is measuring 3 ohms, that's a huge problem.

And again, this thing is going in my mouth, where I keep my really expensive teeth.

Better safe than sorry.

 

[brickfollett]

Can't imagine vaping anything less than .4. Lowest I've gone is .43 and it's pretty nuts. I'm pretty comfortable at .73 on my Reo and it's a pretty crazy vape. I'm not that crazy of a cloudchaser. If you get your build right you can get some crazy vapor without sub-ohming. I was getting very impressive clouds on my RSST with a 2.4 ohm microcoil at 6 volts on the Provari. Certainly rivaling a solid dripper build and the flavor... Oh the flavor from mesh. Regret selling my Pyrex RSST, but I still have the original laying around somewhere

 

[anumber1]

One of the main differences in a cheap meter and a good one lie in the measurment at the low ohm end of the meter.

.05 off at 100k ohms is no big deal.

.05 ohms off when shooting for .1 ohms, well, If someone is pushing limits (.2, that is pushing limits of all but the best meters), the difference is large.

Slightly off topic rant:

Im in it for the flavor and the nicotine. I totally don't understand the "phat cloudz" the pursuit of such without really taking ownership of the risks.
The vape shop I frequent has a steady stream of college age patrons that are showing off their .14 ohm builds and chatting about the cloud potential of super low ohm builds. If these young minds would/could put some thermal engineering into this, I would love to see a movement towards developing builds that max effective surface area and optimum temperature for them clouds instead of punishing batteries.

JMHO and so forth, of course I may be wrong.

I think (my opinion) that anything below .4 ohms or so is pushing limits. The limits of your meter, the funtional tolerance of your battery, the chances of Murphy knocking your teeth out.

I trust my expensive Fluke meter. That said, I don't trust it that much.

 

[anumber1]

Is there a way to check the meters accuracy?

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Yes.

Test/calibration resistors are sold/marketed. They are measured for exact resistnace and marked. You measure them with your meter and note the difference.

Cheap meters may be off by a lot.
I have a really cheap Harbor freight meter that is off by 20%!
I use that one for non critical stuff like continuity testing. Beep or no beep. That is what that one is good for.