RDA Does my first RDA build look okay?

[jersey_emt]

this is that build, it's working okay but there's a lot of spitback. i might have just over filled it though. i went with 8 wraps to get .3 ohms, didn't want it to be too low...it came out exactly .3 ohms

Overfilling can cause spitback, but it can also be caused by having a coil that is heating up too slowly. Eight wraps of twisted 24 gauge wire is a lot of mass, especially since it appears you went up to a 3.5 mm diameter coil for that build (I could be wrong, you never provided the diameter of your builds).

If it is still spitting back even when the juice well is not overfilled, then you will need to bump up your wattage, so that the coil can heat up fast enough to vaporize all of the juice instead of vaporizing some and boiling the rest. You should also open up the airflow as much as your rda allows with a build like that.

 

[Jumberlack]

Overfilling can cause spitback, but it can also be caused by having a coil that is heating up too slowly. Eight wraps of twisted 24 gauge wire is a lot of mass, especially since it appears you went up to a 3.5 mm diameter coil for that build (I could be wrong, you never provided the diameter of your builds).

If it is still spitting back even when the juice well is not overfilled, then you will need to bump up your wattage, so that the coil can heat up fast enough to vaporize all of the juice instead of vaporizing some and boiling the rest. You should also open up the airflow as much as your RDA allows with a build like that.

i'm not sure what diameter it is, i'm just using an allen wrench to make them. here's a size comparison to my rda

i'll probably retry this build with 6 or 7 wraps instead, since i barely even got this one to fit in the deck. should that still be over 0.2 ohms?

 

[Two_Bears]

Overfilling can cause spitback, but it can also be caused by having a coil that is heating up too slowly. Eight wraps of twisted 24 gauge wire is a lot of mass, especially since it appears you went up to a 3.5 mm diameter coil for that build (I could be wrong, you never provided the diameter of your builds).

If it is still spitting back even when the juice well is not overfilled, then you will need to bump up your wattage, so that the coil can heat up fast enough to vaporize all of the juice instead of vaporizing some and boiling the rest. You should also open up the airflow as much as your RDA allows with a build like that.

Move the coils further out to the wall for less spitback too.

Consider 26 or 28 gauge. Will ramp up much faster than 24.

 

[93gc40]

i'm not sure what diameter it is, i'm just using an allen wrench to make them. here's a size comparison to my rda

i'll probably retry this build with 6 or 7 wraps instead, since i barely even got this one to fit in the deck. should that still be over 0.2 ohms?

The Allen wrench size is you diameter. Or at least close enough for reference.

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[sonicbomb]

OP is still not listening. On a regulated mod the resistance is of no real consequence. Big coils with lots of mass will take a long time to heat up even with relatively high power levels, and will then take a long time to cool off while continuing to cook the wick and juice.

 

[Jumberlack]

OP is still not listening. On a regulated mod the resistance is of no real consequence. Big coils with lots of mass will take a long time to heat up even with relatively high power levels, and will then take a long time to cool off while continuing to cook the wick and juice.

i am listening, and since that 24g twisted coil took a long time to ramp up i switched it with a simple 24g 7 wrap dual coil for now until i can find a good combination for around 0.3 ohms without having too many or too little wraps

 

[sonicbomb]

Ok cool, glad you getting closer to where you want to be.

 

[jersey_emt]

OP is still not listening. On a regulated mod the resistance is of no real consequence.

i am listening.......until i can find a good combination for around 0.3 ohms without having too many or too little wraps

No, you are not. You're still stuck on this 0.3 ohm target. Resistance is meaningless on a regulated mod for the most part.

What is important is heat flux and heat capacity. Both are calculated by the Steam Engine coil calculator previously linked. Heat flux determines how "hot" or "cool" the vape is, while heat capacity tells you how long the ramp-up time will be.

Heat flux is a personal preference, but around 200 mW/mm² is a good starting point (be sure to enter in the wattage you intend to use into the calculator on the rightmost column where it says "Heat flux @ X watts). If you like a hotter vape, then in your next build aim for a higher heat flux, and a lower heat flux if you want a cooler vape.

You want the heat capacity to be as low as possible while maintaining your preferred heat flux. Any dual coil build with a heat capacity over around 100 mJ/K for each coil will have a very noticeable ramp-up time.

 

[ErrrKT19]

i used premade twisted coils for it, but im not sure if it's normal. it's 0.18 ohms View attachment 617659

looks great

 

[ErrrKT19]

resistance is significant in regards to battery discharge rate. same power with a lower resistance = higher current resulting in a shortened battery life

 

[Psofos]

If using a regulated mod,ignore the resistance,it doesn't matter.
It only matters in mechanical mods.
To calculate amps divide the watts with the lowest cut off battery voltage to be safe.
If you have a single 18650 mod and vape at 70 watts, 70watts/3.0volts=23A
If the battery is full, 70watts/4.2volts=16A.
If you have dual 18650 mod and vape at 70 watts, 35watts(each battery)/3.0volts=11A and so on.
Targeting 0.3 ohms and nothing else,serves no purpose.
The advice you were given about heat flux by jersey_emt is what you should follow.
Dual 26g 6 wraps are too hot at 90 watts for example. Dual 24g 6 wraps are too cold at 40 watts.
That's what you should build around,not an ohm target.

 

[KenD]

resistance is significant in regards to battery discharge rate. same power with a lower resistance = higher current resulting in a shortened battery life

Not true. Watts are watts, and they determine the battery draw. Higher resistance requires higher voltage from the batteries, lower resistance demands less voltage. Volts are exchanged for amps and vice versa. Resistance simply has no bearing on the battery draw on a vw device.

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[jersey_emt]

resistance is significant in regards to battery discharge rate. same power with a lower resistance = higher current resulting in a shortened battery life

Nope, not on a regulated mod, where the voltage from the battery is boosted or bucked to whatever will give the desired wattage. Battery capacity should really be given in watt-hours, not amp-hours.

 

[sonicbomb]

 

[ErrrKT19]

Nope, not on a regulated mod, where the voltage from the battery is boosted or bucked to whatever will give the desired wattage. Battery capacity should really be given in watt-hours, not amp-hours.

Not true. Watts are watts, and they determine the battery draw. Higher resistance requires higher voltage from the batteries, lower resistance demands less voltage. Volts are exchanged for amps and vice versa. Resistance simply has no bearing on the battery draw on a vw device.

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that'll teach me to forget the lesson of watt hours i learned when the dna200 board came out, doh! thanks for setting me straight >=)