First build help

[VerrazanoBridge]

I have a Fuhattan mod Plume Veil RDA
Efest IMR 18650 High drain 35A 2500 mAh
28 Gauge Kanthal A1

I'm wondering what's a good resistance for a dual coil build, that's safe with my set up. What's a good range the resistance should be. So I can play around with it.

Oh the resistance and ohms are the same right?

 

[State O' Flux]

Welcome to the asylum...

The resistance of a circuit or pathway is measured in Ohms. A circuit with high conductivity will have zero to milliohm (one-thousands of an ohm) resistance, while a material that has some level of resistance to conductivity will have a value in Ohms from above milliohms to mega ohms and/or a fully "open" circuit.

The "optimistically advertized" 35A/2500mAh Efest battery has a "true' continuous discharge of around 20A... beyond that, the battery temperature rises to unsafe levels that will shorten the life span of the battery at best and, at worst may lead to dangerous thermal runaway. You can run to 25 and 30 amps, but limit the use to a ten second or less "pulse".

Every wire gauge has an optimal build resistance range, depending on the wattage supplied and the number of coils in parallel. Your 28 gauge wire, on a mech mod - where Ohm's law values are calculated to determine wattage available at 'X' resistance... and then the build is fashioned to compliment that wattage - work nicely with a dual parallel, 0.55Ω net resistance. Your battery drain (calculated at 4.2V) at this resistance is a modest 7.6 amps.

In the above paragraph, the first link is to Steam Engine Ohm's law calculator - load 4.2 volts and 0.55Ω to see your wattage and amperage discharge values.
The second is to the SE build modeling program with a 0.55Ω dual coil build loaded at the Ohm's law wattage (32 watts) provided by the calculator. The heat flux (coil radiant temperature) is nicely warm at 258 mW/mm², and the heat capacity (time to temperature is a reasonably low 16.25 mJ/K.

You can use the calculated specifications on the right side of the page to build your coils. The only values that determine resistance are wire gauge and type, and wire length... the number of wraps are a product of wire length and mandrel diameter, and have no effect on resistance. If you decrease the mandrel diameter (coil ID), your wrap count will increase.

To learn more about using Steam Engine, as well as mech mods and battery safety... click the sigline hyperlinks below.

 

[VerrazanoBridge]

Awesome thank you so much for that! It's gonna take me a little bit to fully understand everything but I get the concept.

2 other questions
1: what mm wrap should I use 1.5, 2, 2.5, 3, 3.5?

2: is it bad to charge the 18650 keep it fully charged and not use them?
And how low (# of volts) should it be before I take it out and charge.
Thank you so much!

Welcome to the asylum...

The resistance of a circuit or pathway is measured in Ohms. A circuit with high conductivity will have zero to milliohm (one-thousands of an ohm) resistance, while a material that has some level of resistance to conductivity will have a value in Ohms from above milliohms to mega ohms and/or a fully "open" circuit.

The "optimistically advertized" 35A/2500mAh Efest battery has a "true' continuous discharge of around 20A... beyond that, the battery temperature rises to unsafe levels that will shorten the life span of the battery at best and, at worst may lead to dangerous thermal runaway. You can run to 25 and 30 amps, but limit the use to a ten second or less "pulse".

Every wire gauge has an optimal build resistance range, depending on the wattage supplied and the number of coils in parallel. Your 28 gauge wire, on a mech mod - where Ohm's law values are calculated to determine wattage available at 'X' resistance... and then the build is fashioned to compliment that wattage - work nicely with a dual parallel, 0.55Ω net resistance. Your battery drain (calculated at 4.2V) at this resistance is a modest 7.6 amps.

In the above paragraph, the first link is to Steam Engine Ohm's law calculator - load 4.2 volts and 0.55Ω to see your wattage and amperage discharge values.
The second is to the SE build modeling program with a 0.55Ω dual coil build loaded at the Ohm's law wattage (32 watts) provided by the calculator. The heat flux (coil radiant temperature) is nicely warm at 258 mW/mm², and the heat capacity (time to temperature is a reasonably low 16.25 mJ/K.

You can use the calculated specifications on the right side of the page to build your coils. The only values that determine resistance are wire gauge and type, and wire length... the number of wraps are a product of wire length and mandrel diameter, and have no effect on resistance. If you decrease the mandrel diameter (coil ID), your wrap count will increase.

To learn more about using Steam Engine, as well as mech mods and battery safety... click the sigline hyperlinks below.

 

[State O' Flux]

Awesome thank you so much for that! It's gonna take me a little bit to fully understand everything but I get the concept.
No problem. You'll learn best by using the SE program while following my SE user guide.

2 other questions
1: what mm wrap should I use 1.5, 2, 2.5, 3, 3.5?
I have the SE file set at 7/64" or 2.7mm... which ever method of measurement you prefer. I like 2.7mm because it's a nice combination of radial surface area and cotton wick thickness. Your wrap count will be reduced compared to smaller ID coils (however, your net coil surface area remains the same)... but like I said, its' a balance of components that provides the best performance.
If you experiment with smaller and larger coils... say 1.5~3.5mm... you'll have a better understanding of why I tend to stay in the 2.5~3.0mm range with RDAs.
Saying that... the physical "space" available to you with certain RDAs can frequently dictate how large and/or long a coil can be.

2: is it bad to charge the 18650 keep it fully charged and not use them?
Once charged, store it in a dry, safe, short-proof container... like a plastic battery box. Don't leave a battery on a charger indefinitely. Develop a rotation system so no battery sees constant use, or lack of use.

When you end up with 30~40 batteries eventually... keep a log of battery purchases & ID label batteries, dates put into service, maximum starting voltage (when new - for later comparison) and what devices the "preferred" batteries will go in - as in slight length variations, battery "marriages" for multi battery devices etc etc.

And how low (# of volts) should it be before I take it out and charge.
Thank you so much!

With a mech, you'll probably start to notice a drop-off of vaping performance at around 3.4V+/-... it depends on the quality of mech, battery net resistance, wick and juice blend used.
I have noticed that very high quality mechs with zero/near zero voltage drop - combined with high quality, low voltage sag batteries can perform quite well down to around 3.2~3.3V.

 

[VerrazanoBridge]

Thank you!

 

[VerrazanoBridge]

With a mech, you'll probably start to notice a drop-off of vaping performance at around 3.4V+/-... it depends on the quality of mech, battery net resistance, wick and juice blend used.
I have noticed that very high quality mechs with zero/near zero voltage drop - combined with high quality, low voltage sag batteries can perform quite well down to around 3.2~3.3V.

I cannot thank you enough for the help! I'm sorry I have one last question and I'm all set. Will these batteries be ok with the same .55ohm settings on my mod?
Samsung 18650 35A discharge rate INR18650-25R li-ion battery 2500mah

 

[State O' Flux]

Yes... the Samsung is well rated. The absolute best source of current, vape related battery testing and data can be found at ECF... as performed by my "personal battery maven"... Mooch.

Once you spend some time with an Ohms law calculator, you'll find yourself remembering the wattage and/or amperage for your particular favorite builds. Speaking of calculators, here's a very simple one that I use frequently... I like that it includes the formulas in an "Ohm's Law Wheel" below it.

It's handy if you want to show the math for OL, like...

• For wattage ("Power") the formula is V² ÷ Ω = P.
• For amperage ("Current") the formula is V ÷ Ω = C.

Ciao!

 

[VerrazanoBridge]

Yes... the Samsung is well rated. The absolute best source of current, vape related battery testing and data can be found at ECF... as performed by my "personal battery maven"... Mooch.

Once you spend some time with an Ohms law calculator, you'll find yourself remembering the wattage and/or amperage for your particular favorite builds. Speaking of calculators, here's a very simple one that I use frequently... I like that it includes the formulas in an "Ohm's Law Wheel" below it.

It's handy if you want to show the math for OL, like...

• For wattage ("Power") the formula is V² ÷ Ω = P.
• For amperage ("Current") the formula is V ÷ Ω = C.

Ciao!

Hey I just noticed on the steam coil build page there's no option for dual coil "parallel" so I don't know how many wraps I need to make in order to get a .55 ohm reading. I'm a little confused.

 

[martinelias]

That setup looks nice. With the 28g id try triple parallel, about 6 wraps for a solid .2 ohm. Not too complicated and will get you a nice flavorful vape.

 

[VerrazanoBridge]

That setup looks nice. With the 28g id try triple parallel, about 6 wraps for a solid .2 ohm. Not too complicated and will get you a nice flavorful vape.

What should the diameter of the coil be? Is 3.5 or 3.0 ok?

 

[VerrazanoBridge]

What should the diameter of the coil be? Is 3.5 or 3.0 ok?

Also dual or single coil? Thanks!