HV Microcoils

[Aal_]

So I thought of sharing my latest experiments in a separate thread. I have been microcoiling (Microcoil: credit super_X_drifter) for a while now and my sweet spot is a plain old 28 gauge kanthal wrapped around 1.4mm jig with 10 wraps totaling 1.1 ohms. Usually my sweet spot with this kind of wire and depending on juice is 13-16. Sometimes I go with lower gauge wire to decrease resistance while keeping the 10 wraps and run on a mechanical with this kind of wattage. With VV/VW devices, I tend to keep this setup and run around 15 watts or so.

Now what I am after is trying to maximize battery life especially on VV/VW devices and therefore minimize the amps drawn, which also doesn't stress the battery. After being explained how VV/VW converters work in brief (credit: Alexander Mundy) and understood that watts determine what is being drawn from battery and not load resistance or output voltage, I realized that what i am after is a good vape with lower wattage. From microcoils builds I noticed that the lower the gauge, the thicker the wire, and the slowest it heats up. And that is why we increase the wattage everytime we go to a lower gauge to have a satisfying vape.

So going the other way round, I thought what if we use higher gauge wires, this way we can decrease the wattage needed. The problem with using a higher gauge is that with 8-10 wraps microcoil the area of contact with wick would be very small. I know people have been doing microcoils with 32 gauge for a while (nano coils, nano dragon etc..) but i am after the same experience of a regular microcoil. So by calculation I found that to cover the length of wick with 28 guage 10 wraps wire, I would need around 16 wraps of 32 gauge. And this is what I did, it turned out to be around 4.7 ohms.

Tested on a Provari at 6V would lead to around 7.5 watts. The vape was better than expected, I would compare it to a vape with 28 gauge 10 wraps at around 12 watts. Now I put it on a dna 20 device at 9 watts. And there was the surprise. It was outputting vapor and heat compared to the 16-17 watts of my regular microcoils. Flavor wise it was excellent but couldn't compare it enough to make a judgement. After all flavor is what matters.

Now all my VV/VW devices will run at max voltage (and not power) because this is how I spare the batteries and this is how I minimize the current drawn. Of course this can be achieved by using stacked batteries in a mechanical but I will not go this way now.

PS: If someone knows whether running at maximum voltage might affect the VV/VW boards let me know.

 

[jameth]

The couple times I have made a high OHM micro for my DNA20 mods (in a KFL usually), they tend to like hold onto heat, as in the coil will continue to sizzle for a moment after I release the button, while not a huge deal, it was annoying enough to me that I kind of put that idea on the backburner.

Have you had this effect?

 

[Dampmaskin]

Try 30 AGW. Run 10 or 12, or even 14 wraps around your 1.4 mm. You don't have to cover a massive length of wick. Smaller is more efficient.

I cannot imagine that running the Provari at 6V can cause any problems. If it did, the Provari wouldn't allow 6V. It's got all sorts of protection circuits.

 

[Aal_]

The couple times I have made a high OHM micro for my DNA20 mods (in a KFL usually), they tend to like hold onto heat, as in the coil will continue to sizzle for a moment after I release the button, while not a huge deal, it was annoying enough to me that I kind of put that idea on the backburner.

Have you had this effect?

Nope never got this effect. not any different than any coils I made.

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[Aal_]

Try 30 AGW. Run 10 or 12, or even 14 wraps around your 1.4 mm. You don't have to cover a massive length of wick. Smaller is more efficient.

I cannot imagine that running the Provari at 6V can cause any problems. If it did, the Provari wouldn't allow 6V. It's got all sorts of protection circuits.

I ran 30 awg for a long time. The idea is to go higher gauges for faster heat up. Smaller is not efficient. I don't know why you say this. Can you explain more? It is not efficient when using a slow heating wire and thus the purpose of the experiments.

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[Dampmaskin]

There are two opposite effects:

1) Thicker wire has less resistance, so for any given voltage the current and therefore the power becomes larger, leading to faster heatup.

2) Thicker wire has more mass (and thus a larger heat capacity), leading to slower heatup. If you increase the length of the wire to compensate for the lower resistance, this effect becomes even stronger.

For a mech mod, point 1 can outweigh point 2. For a regulated mod, point 1 can be negated by increasing the voltage. So I may be wrong, but it is my understanding that with a good regulated mod, thinner wire can be made to heat up faster than thicker wire.

 

[Aal_]

The whole point is to have the best vape with the least current drawn from a single battery in a regulated device.
Regarding surface on wick with 28 gauge wire you cover 3.2mm with 10 wraps. To get fast heat up time on this setup my sweet spot is 16 watts.
Now to get the same amount coverage with 32 gauge wire which is 3.2mm you need 16 wraps. But you can achieve the same heat up time of the previous setup at 9 watts.
This setup will draw less amps of the battery than the previous setup although the voltage is higher because of the nature of converters.

Now the point I didn't get is that you saying that covering a smaller wick is more efficient. If by this you mean your coil is heating up faster it is because it is at higher watts and thus negating the purpose of my experiment.

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[super_X_drifter]

Good thread bro. I have always preferred more wraps on my VV grand. I average 12-13 on it but have run as high as 16 or 17 with 30 ga. I now use 29 ga Kanthal exclusively for mechs and VV.

That's the beauty of a proper inside diameter micro coil - you can get away with mucho wraps. My favorite inside diameter for all builds is .055"

Ironically the last time I wrapped a coil for my VV grand I only wrapped 10 wraps. Ima redo it when my keh gen do cotton arrives and I'll try an 18 wrap if it fits on my cyclone.

Here's a pic from back in the day of a nano with a bunch of wraps:

I don't mess with nanos anymore because I like to wick thru the coil and it's not as easy to thread a nano as it is a micro

 

[Aal_]

Thanks superx. Well you said it more wraps is the best combined with adequate heating time.

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[MasterofNone]

Good thread bro. I have always preferred more wraps on my VV grand. I average 12-13 on it but have run as high as 16 or 17 with 30 ga. I now use 29 ga Kanthal exclusively for mechs and VV.

That's the beauty of a proper inside diameter micro coil - you can get away with mucho wraps. My favorite inside diameter for all builds is .055"

Ironically the last time I wrapped a coil for my VV grand I only wrapped 10 wraps. Ima redo it when my keh gen do cotton arrives and I'll try an 18 wrap if it fits on my cyclone.

Here's a pic from back in the day of a nano with a bunch of wraps:

I don't mess with nanos anymore because I like to wick thru the coil and it's not as easy to thread a nano as it is a micro

Keh gen do cotton ?


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[MFToms59]

The couple times I have made a high OHM micro for my DNA20 mods (in a KFL usually), they tend to like hold onto heat, as in the coil will continue to sizzle for a moment after I release the button, while not a huge deal, it was annoying enough to me that I kind of put that idea on the backburner.

Have you had this effect?

What Gauge & type wire, 28/30/32, Kanthal/ Nichrome/ Renee?

 

[super_X_drifter]

Keh gen do cotton ?


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My bad - it's Koh Gen Do. Lotsa discussion about it in REOsmods forums

 

[MasterofNone]

I got to go back home and look around lol


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[Dampmaskin]

Now the point I didn't get is that you saying that covering a smaller wick is more efficient. If by this you mean your coil is heating up faster it is because it is at higher watts and thus negating the purpose of my experiment.

Covering less wick means that less juice will be cooling the coil. With less juice cooling the coil, and the coil being smaler, thus itself having a smaller heat capacity, the coil will reach "working temperature" faster with the same amount of power delivered from the APV.

The coil might also vaporize a smaller volume of juice at a time, so that might not be desirable depending on your preferences.

 

[Aal_]

Covering less wick means that less juice will be cooling the coil. With less juice cooling the coil, and the coil being smaler, thus itself having a smaller heat capacity, the coil will reach "working temperature" faster with the same amount of power delivered from the APV.

The coil might also vaporize a smaller volume of juice at a time, so that might not be desirable depending on your preferences.

What you said in your second point is what actually prohibits us from making assumptions made by your first point . Let us talk about efficiency. Our output is nothing but vapor production, or in other words, the quantity of liquid vaporized. Our input is the power needed to vaporize this juice. So the 2 variables are power consumed vs quantity of juice vaporized. To increase efficiency we either increase the vapor produced with the same amount of power, or reduce the power for the same amount of vapor produced or a combination of both.
Now with what you are saying, decreasing the width of the coil will have a self destructing effect. Although it speeds up the heat up time as you have noted producing more vapor, it also covers less liquid which produces less vapor. Now which effect is less and which is more? beats me! But from experiments, I believe that covering more area produces more vapor than what is lost due to extra cooling of the wire.
And that is why in my trial I chose a width of coil that I am familiar with. I made the coil 3.2mm so I can compare apples to apples with the 10 wraps of 28 gauge which is also 3.2mm in width. The result is clear I achieved higher efficiency because I got the same amount of vapor/experience with 9 watts than with 16 watts. Of course again this is on VV/VW. On a mech it wouldn't be higher efficiency since you will have to stack 2 batteries.

 

[Flavored]

Delivery of juice to the coil, ie - wicking efficiency, plays a large part, as well.

 

[Aal_]

Delivery of juice to the coil, ie - wicking efficiency, plays a large part, as well.

Of course. All my claims are based on a perfect delivery of juice. which is not far from reality the moment we started using cotton.

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[Dampmaskin]

Although it speeds up the heat up time as you have noted producing more vapor, it also covers less liquid which produces less vapor. Now which effect is less and which is more? beats me! But from experiments, I believe that covering more area produces more vapor than what is lost due to extra cooling of the wire.

Coils don't only heat up the liquid being vaporized, but also the rest of the liquid in the atty, and the atty itself. This heat is dissipated. In my experience, big coils do this more than small coils. That's why I think smaller coils are generally more efficient. I may still be wrong, though.

 

[Aal_]

Coils don't only heat up the liquid being vaporized, but also the rest of the liquid in the atty, and the atty itself. This heat is dissipated. In my experience, big coils do this more than small coils. That's why I think smaller coils are generally more efficient. I may still be wrong, though.

You are right in this. Heat lost to the surrounding would be bigger with a bigger coil. I agree. However to what extent? We don't have accurate way to measure it. Again based on my experience still wider coils generate more output. And my experience is based on microcoils (1.4mm to 1.65mm). I don't know about larger coils. Hopefully someday we can make accurate measures but I doubt if the benefits will outweigh the effort .

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[Aal_]

And by the way I need to point out one more thing. Have you measured the amount of condensation inside the atomizer. Heat dissipation to the body reduces efficiency but at the same time reduces condensation inside the atomizer which increases efficiency. So it is a lot of parameters all at once

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