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New to Building Coils, are my current calculations correct?

Hello everybody, I ordered a Smok Baby Beast RBA and a building kit. I want to try and build my own coils, and I need some help and clarification. I have a Smok Alien 220w mod, and with two 18650 batteries. They are LG HG2's with 3000mAh and 3.7 volts. According to their specs that I read they are rated at 20A maximum each.

So from what I read online, since I have two batteries, each battery will draw 110w, and since I have two 3.7v batteries I have a total of 7.4v. Does this also mean I have a total of 40A with the batteries, since there are two of them?

The current build that I want to do I input the building info into a Coil Building Calculator on my phone, the details are:

Dual Core setup, with 24AWG Kanthal A1
Inner Diameter of Each Coils is 3.0mm
Leg Length is 5mm
Number of wraps is 7 per coil
Resistance according to calculator: 0.166ohms
Current: 22.4A

Is this ok? Would this be safe?
 

PoppaVic

Gold Contributor
Member For 4 Years
that'd be a series-mod (regulated) meaning the amps are the same as single cell, so no: you are overdrawing.

I'd take that up to .3ohm, at least for myself. And, 24awg is pretty hefty - having used the stuff before I'd never go heavier than 26awg or yer waiting all day for a vape.
 
that'd be a series-mod (regulated) meaning the amps are the same as single cell, so no: you are overdrawing.

I'd take that up to .3ohm, at least for myself. And, 24awg is pretty hefty - having used the stuff before I'd never go heavier than 26awg or yer waiting all day for a vape.
Thank you so much!! You have no idea how much you helped me!!

Just one more question. I know the cotton will eventually burn out, but how often should I replace the actual coil?
 

PoppaVic

Gold Contributor
Member For 4 Years
I may change them once a week, or once a month. Usually when I dryburn and SS brush the coils. Just did my Vt133 tonight, it's been about a month and the SXK boxer got done yesterday, but I vape that almost daily at home.

If the taste goes "off", it's time to clean or replace coils. That always necessitates wicking. Sometimes the coils need to be replaced, (maybe ever 3rd or 5th dryburn/brush).

Also learn: http://www.steam-engine.org/coil.html?mat=ss316l&p=roundmulti&r=0.2&str=2&awg=26&id=3
 

Carambrda

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The Smok Alien is a regulated mod. For regulated mods, the ohms are irrelevent when calculating the battery safety. A quick rule of thumb for this is to just take the true Continuous Discharge Rating (CDR) of the battery you select for vaping, and multiply it by three. This gives you the maximum wattage you can vape per battery on a regulated mod so, because the Smok Alien is a dual battery regulated mod, multiply this number by two batteries. I.e., up to 120 watts with a pair of LG HG2 batteries in a dual battery regulated mod is considered relatively safe enough to be able to recommend to those who ask how much is safe. However, please note that the CDR number is not always reported accurately, and that this is why it is always recommended to consult Mooch's battery test reports or his continually updated battery ratings and performance tables. That said, the 20A rating of the LG HG2 is actually correct, but also please note that there are no hard and fast numbers that either are safe or are unsafe, and that the CDR reported by Mooch is what's generally thought to be a reasonable limit, what people find to be an acceptable, or small enough level of risk when taking all the other battery safety related guidelines also properly into account. A damaged battery wrap or damaged top insulator ring on the battery can short circuit the battery, which is much more dangerous than going a little bit over the CDR, although people shouldn't use that for a pretext to not recommend to stay at or below the CDR.
 

nadalama

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Looks to me like your calculation of resistance is wrong.

Steam-engine.org is showing me 0.67 ohms per coil using the specs you stated. Dual coils would net half that, so about 0.33.

Sounds sluggish to me. That's a lot of metal unless you're going to vape it at better than 60W.
 

MyMagicMist

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Ha ha! I have you fooled. I got a 3 wrap around 3 mm ID running at 0.45 ohm 26 awg Kanthal. It's on a Topside Lite at a blazing 20 watts. I am using a 20700 battery to push this modern marvel along. Change the coil? Bah! it'll need to be rusted away by the juice first! Then, I'll go get some of @The Cromwell 's copper wire he uses.

Matter o' fact think I've roughly the same coil in all my mods, mechanical or regulated. If it's not Kanthal, it's SS316L but I do believe it's all 26 awg reading around 0.35 to 0.45 with a 3 mm ID. This works out quite well for me on single cell 18650s or the 20700 batteries. Nope, no dual coils for me. Don't see any need for 'em. No Claptons, nothing fancy either, again just see no need.
 
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Looks to me like your calculation of resistance is wrong.

Steam-engine.org is showing me 0.67 ohms per coil using the specs you stated. Dual coils would net half that, so about 0.33.

Sounds sluggish to me. That's a lot of metal unless you're going to vape it at better than 60W.
You're right! Sorry, I forgot that I was making each coil a parallel coil, which gave me the results I posted, but when I switched to single coil, it gave me the results you stated.
 

nadalama

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You're right! Sorry, I forgot that I was making each coil a parallel coil, which gave me the results I posted, but when I switched to single coil, it gave me the results you stated.

So you'll essentially be running four KANTHAL coils. Jeepers. How are you even getting that into a BB RBA? Don't think I could do it - there's just not enough room!

Good luck. Maybe some of these high-wattage guys will think I'm full of it, but I'd cut way back on the metal, if I were doing the building. But that wasn't your question in the first place. I'll be interested to hear how it goes for you.
 

Bigrick

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If I remenber correctly the BB rba comes pre coiled with a couple of little claptions. That will give something to gauge what types of future builds it will fit. Actually works as well as most of my rta's. I do not use prebuilt factory coils at all any longer.
 

nadalama

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I have a baby RBA, you're not going to fit a 7 wrap 24 gauge parallel coil in there and 3mil diameter is pushing it

Sent from my SM-G970U using Tapatalk

Um, yeah. That's a big coil.
 
I have a couple more questions. If I increase the wattage on a custom coil does the voltage increase? My mod has 2 3.7v 18650 batteries. If I increase the wattage would I run the risk of going past the 3.7v limit? And does the amperage increase if I increase wattage too? My batteries are rated at 20A max, so if I increase the wattage would I run the risk of going past 20A?
 

Carambrda

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I have a couple more questions. If I increase the wattage on a custom coil does the voltage increase? My mod has 2 3.7v 18650 batteries. If I increase the wattage would I run the risk of going past the 3.7v limit? And does the amperage increase if I increase wattage too? My batteries are rated at 20A max, so if I increase the wattage would I run the risk of going past 20A?
With a regulated mod you don't need to worry about how many volts are delivered to the coil. The chip inside the mod automatically calculates it on-the-fly, and keeps doing so multiple times per second during every puff as it keeps measuring both the resistance of the coil and the input voltage that it receives from the battery so, based on how many watts you set on the mod, this voltage gets converted to a different voltage through a buck/boost circuit. This is what's called the output voltage, which is delivered to the coil. Now, because the input voltage goes down with every puff as a result from discharging the battery further, the mod draws more current in order to compensate, to be able to keep the wattage invariable. Therefore, the current gradually goes up until the batteries finally run low and the mod stops, at 3.2V for the Smok Alien, the voltage cut-off of the mod.

The 3.7V that you are referring to is not a limit. Rather, it is the nominal voltage of the battery, and, it is irrelevant for calculating the battery safety. I already answered how to calculate it in my previous reply. As for the coil resistance, you only need to make sure that it is within the range that the mod can handle according to the specs that are in the user manual of the mod. If the resistance is too low, the mod will refuse to fire the coil. If it's too high, either it won't fire or else you won't be able to get a high enough wattage for how you want to vape. Depending on the mod's hardware it can also happen that it begins to throttle the wattage down after it can no longer sustain the wattage you set on the mod. But you shouldn't set the wattage higher than 120 watts when vaping on a pair of LG HG2s, as doing that is going to exceed the CDR of 20A for the LG HG2.
 

gsmit1

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I have a baby RBA, you're not going to fit a 7 wrap 24 gauge parallel coil in there and 3mil diameter is pushing it
I was looking to see if somebody else brought this up before I did. This is a good RBA, but there is no way 7 wraps of anything at 3mm is going in there. I use 2.5 and maybe 5 wraps. Small deck, tight chamber.

Set it up right and it's a great vape, but it has it's limits. Don't underestimate the vapor production you can get with a pair of smaller coils.
 
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gsmit1

Platinum Contributor
Member For 4 Years
@ElOgre


Do yourself a favor while you're learning. It looks like you have some 24ga Kanthal

Wrap 5 wraps on a 2.5mm rod. X2 of course. 2 coils. Mount them in the posts so you can pull them down close to those airflow holes without touching. Be careful that they don't extend far enough to touch the cap. You'll get the hang of it.

Also, get the screws tight, but don't overtighten. Those are small screws. You do not want to strip one out in there.

These will come out to around .2 and a little change for the pair. Start at about 40 watts when you get it wicked and primed (ask if you need help with that too) and go up by 5 watts at a time until you like the vape. I'm betting that will be below 70 watts. Don't get hung up on huge wattage. It's not necessary to get a great vape. This will be well within the usable range for the batteries you have.

I'm not trying to run your life, but most people need to be told EXACTLY what to do to get started. This will get you vaping with your setup and you can learn more as you go.
 

Creature0069

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Short, simple answers:
If I increase the wattage on a custom coil does the voltage increase? Yes

If I increase the wattage would I run the risk of going past the 3.7v limit? Some mods will allow this to happen, most won't.

And does the amperage increase if I increase wattage too? Yes

My batteries are rated at 20A max, so if I increase the wattage would I run the risk of going past 20A? Possible but, more likely the mod wouldn't fire OR will fire at a lower wattage than set to AND/OR give you a weak battery warning.

A good rule of thumb with batteries, if they get HOT, you're pushing them too hard. That being said, with a regulated mod, there's MUCH less risk as it simply won't give you the power you ask for if it's not available.

@gsmit1 gave some good advice above. Most of my tanks have .25-.3ohm coils and I'll vape them anywhere from 50-60w. Currently rocking a single .24ohm 2.5mm coil at 56w (3.71v and 15.5A) and I'm exhaling weather systems. :cheers:
 

mkbkr1

Member For 4 Years
Do yourself a favor and watch DJLSB's review of the Smok Alien. He does in depth tests of the actual applied voltage and current at different resistances. You can learn a lot from his videos.

Sent from my SM-G970U using Tapatalk
 

BoomStick

Gold Contributor
Member For 5 Years
You’ve gotten shit advice. You’re using a regulated mod. Build resistance has nothing to do with battery current.
With a regulated mod you don't need to worry about how many volts are delivered to the coil. The chip inside the mod automatically calculates it on-the-fly, and keeps doing so multiple times per second during every puff as it keeps measuring both the resistance of the coil and the input voltage that it receives from the battery so, based on how many watts you set on the mod, this voltage gets converted to a different voltage through a buck/boost circuit. This is what's called the output voltage, which is delivered to the coil. Now, because the input voltage goes down with every puff as a result from discharging the battery further, the mod draws more current in order to compensate, to be able to keep the wattage invariable. Therefore, the current gradually goes up until the batteries finally run low and the mod stops, at 3.2V for the Smok Alien, the voltage cut-off of the mod.

The 3.7V that you are referring to is not a limit. Rather, it is the nominal voltage of the battery, and, it is irrelevant for calculating the battery safety. I already answered how to calculate it in my previous reply. As for the coil resistance, you only need to make sure that it is within the range that the mod can handle according to the specs that are in the user manual of the mod. If the resistance is too low, the mod will refuse to fire the coil. If it's too high, either it won't fire or else you won't be able to get a high enough wattage for how you want to vape. Depending on the mod's hardware it can also happen that it begins to throttle the wattage down after it can no longer sustain the wattage you set on the mod. But you shouldn't set the wattage higher than 120 watts when vaping on a pair of LG HG2s, as doing that is going to exceed the CDR of 20A for the LG HG2.
Read this. Ignore the others speaking about battery stuff.
 

BoomStick

Gold Contributor
Member For 5 Years
that'd be a series-mod (regulated) meaning the amps are the same as single cell, so no: you are overdrawing.

I'd take that up to .3ohm, at least for myself. And, 24awg is pretty hefty - having used the stuff before I'd never go heavier than 26awg or yer waiting all day for a vape.
Wrong.
 

Don29palms

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You’ve gotten shit advice. You’re using a regulated mod. Build resistance has nothing to do with battery current.

Read this. Ignore the others speaking about battery stuff.
And this is shit advice. Carambrda is a lying asshole and his advice is bad and dangerous. Even with a regulated mod all elements still work together.
 

BoomStick

Gold Contributor
Member For 5 Years
And this is shit advice. Carambrda is a lying asshole and his advice is bad and dangerous. Even with a regulated mod all elements still work together.
Carambrda is a douche, and apparently you don’t understand how variable wattage works. Explain how build resistance has anything to do with battery current when the wattage setting isn’t known? Fuck off.
 

Carambrda

Platinum Contributor
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Member For 5 Years
If I increase the wattage would I run the risk of going past the 3.7v limit? Some mods will allow this to happen, most won't.
No. There simply exists no 3.7V limit.
A good rule of thumb with batteries, if they get HOT, you're pushing them too hard. That being said, with a regulated mod, there's MUCH less risk as it simply won't give you the power you ask for if it's not available.
No, and no. The temperature on the outside of the battery does not reflect how hot the battery gets on the inside, as pushing the battery hard causes the weakests spots, or small areas that generate more heat than average inside the battery to potentially overheat despite the outside surface temperature of the battery may barely even get warm, as heat takes time to propagate from these smaller areas towards the bigger, surrounding areas which heat up slower in comparison so, because it takes time, localized heat buildup is an important added factor to also want to properly take into account, when you can't know for sure that any technical failure of the mod will not be causing the battery to get drained continuously until it overheats to a potentially catastrophic level, if the battery you select for vaping has a CDR that is too low for the wattage you're at.


 

Carambrda

Platinum Contributor
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Member For 5 Years
BoomStick has a small penis, and, worse, he doesn't understand a thing about battery safety─which I can prove, like so:

(Please note, some of the battery choices explained towards the end in the video above are a bit outdated, as Mooch continually keeps updating with info about new choices as they become available to us, but the battery related safety principles explained in the rest of the video are nonetheless applicable.)

 
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gsmit1

Platinum Contributor
Member For 4 Years
You’ve gotten shit advice. You’re using a regulated mod. Build resistance has nothing to do with battery current.
Don't you think it might be a good idea to get this guy vaping for now and then he can start learning the electronics later? You don't have to be an electrical engineer to build for and use a regulated device or learn basic safety.
 

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