sub ohm power question

[kdubbie]

I have been pretty content with my very simple setup of itaste vv/protank for quite a while now. I use 2.2 or 2.5 ohm coils and I'm good to go. I have always wanted to try rebuildables with sub-ohm resistance, but have been too lazy ... However, with the advent of sub-tanks, I think I'm going to give it a try.

Before I do, there was just something I never quite understood ... When I increase the voltage on my 2.2 ohm pro-tank coils to 4.5 - 5.0 volts, which is only about 8.5 - 12 watts, it burns instantly. I mean two seconds into the pull and I have to stop. And it happens every time. So how is possible to fire a .5 ohm coil at a whopping 30 watts without completely frying the coil?

 

[catalinaflyer]

It has everything to do with the ability of the device the coil is in be it a tank, RBA, RDA etc. to deliver the amount of juice needed by the coil. You can't just crank any atomizer up and get more vapor, it takes design to get the juice to the coil to be used by the coil to make vapor. If you take an Atlantis or KST or any of the other "sub-ohm" tanks and try to run them at 8 watts you'll get almost no vapor because the amount of juice being delivered to the coil is absorbing the heat without turning to vapor. Take almost any non "sub-ohm" tank and crank the wattage up to the levels used by the "sub-ohm" tanks and all you do is burn the coil.

 

[Wolfenstark]

0.5Ω at 30 watts is 3.9v
Its less resistance so it takes a higher wattage to get a higher voltage.
it would take 50 watts on a 0.5Ω to get 5v

 

[CasketWeaver]

Lower Ohms = Higher Watts + Amps to bring desired voltage. However Amp rating is more important than Wattage speaking terms of safety (but that's all beside the point). But to fire a .5 - .6 Ohm coil anywhere near 3.7 volts (basic battery output) - you'd need 15 - 25W. For more information: Google: Ohm's Law. There are plenty of articles out there that will help you understand the math behind all of it. And some of the articles put it in terms that make it very easy to understand how wattage against a set resistance will equal voltage and required amperage.

 

[93gc40]

I have been pretty content with my very simple setup of itaste vv/protank for quite a while now. I use 2.2 or 2.5 ohm coils and I'm good to go. I have always wanted to try rebuildables with sub-ohm resistance, but have been too lazy ... However, with the advent of sub-tanks, I think I'm going to give it a try.

Before I do, there was just something I never quite understood ... When I increase the voltage on my 2.2 ohm pro-tank coils to 4.5 - 5.0 volts, which is only about 8.5 - 12 watts, it burns instantly. I mean two seconds into the pull and I have to stop. And it happens every time. So how is possible to fire a .5 ohm coil at a whopping 30 watts without completely frying the coil?

Simple that .5 ohm coil has about 20x the wire as your 2.5ohm coils. Because they are made from MUCH thicker wire. If they use the same wire as you have they would be vaping off the SUN.

 

[tj99959]

Volts/wattage heat your coil.

Liquid & air flow cool your coil.

Yes, it really is that simple.

It works exactly the same as your car engine. Combustion heats the engine, and the cooling systems keep the engine running at the proper temperature.

Your Protank burning at 5v simply means that there is not enough liquid and/or air at the coil to keep it cool.

 

[mcclintock]

You're leaving out the big one: surface area. The total heat divided by the area determines the Heat Flux. When this is the same, it means the coil's just scaled up. The wicking and airflow also need to be upscaled, of course. These are important factors but can't get you THAT far by themselves. If the coil is bigger, the wick tends to be bigger anyway. The Protank actually gets a good amount of juice to the coil, although the airflow is still on the low side, even for a small thing.

 

[jerseyman32]

Im interested as well, if i use the steam engine chart it tells me in order to build a .5 ohm coil with 28 gauge kanthal i only have to wrap wrap it 3 or 4 times at 2.5 mm, is that correct?

 

[Wissel Joe]

I have 3 sub ohm tanks and the more i use my gs air tanks the less im using the sub ohm tanks.

 

[jerseyman32]

I just ordered one.

 

[edyle]

I have been pretty content with my very simple setup of itaste vv/protank for quite a while now. I use 2.2 or 2.5 ohm coils and I'm good to go. I have always wanted to try rebuildables with sub-ohm resistance, but have been too lazy ... However, with the advent of sub-tanks, I think I'm going to give it a try.

Before I do, there was just something I never quite understood ... When I increase the voltage on my 2.2 ohm pro-tank coils to 4.5 - 5.0 volts, which is only about 8.5 - 12 watts, it burns instantly. I mean two seconds into the pull and I have to stop. And it happens every time. So how is possible to fire a .5 ohm coil at a whopping 30 watts without completely frying the coil?

Because it's a thicker wire coil.

Thicker wire needs more watts per ohm to get hot

You can understand it easily if you imagine a really thick wire coil like the size of wire you see on car battery cables; a thick wire at 2 ohms will be a huge coil and will need a lot more power than a tiny coil in a clearo at the same 2 ohms.

 

[tj99959]

Im interested as well, if i use the steam engine chart it tells me in order to build a .5 ohm coil with 28 gauge kanthal i only have to wrap wrap it 3 or 4 times at 2.5 mm, is that correct?

That's why wire comes in different gauges. I try to keep my coils no less than 5 wraps, and no more than 9 wraps for the best ramp up time and flavor. And, use the wire gauge and coil diameter that will give me the resistance I want within those parameters.

Because it's a thicker wire coil.

You can go to far with that too.

 

[v1k1ng1001]

I prefer to go with higher resistances / more wraps on my single coild builds to increase surface area and then just push more power to the coil as needed.

I feel like the marketers have fetishized the whole sub-ohm thing to push product.

Educate yourself, experiment (safely) and see what works best for you.

 

[mcclintock]

Im interested as well, if i use the steam engine chart it tells me in order to build a .5 ohm coil with 28 gauge kanthal i only have to wrap wrap it 3 or 4 times at 2.5 mm, is that correct?

Yes, but it would be a rather hot coil at normal voltage. With 28 ga. you get a good heat flux with about 1-1.2 ohm per coil, or .5 with dual coils.

Unfortunately, Steam Engine doesn't let you hold voltage constant on the coil calculator, so if you change resistance, for a mech you then need to recalculate power input as well.

Coil wrapping | Steam Engine | free vaping calculators

Another way to do it is use the wire length and wind 'til that length is used up. I did a stovetop coil that way (unlike everyone on youtube that winged it). But for a regular coil you'll want to see about how many turns will be needed anyway.

 

[edyle]

Im interested as well, if i use the steam engine chart it tells me in order to build a .5 ohm coil with 28 gauge kanthal i only have to wrap wrap it 3 or 4 times at 2.5 mm, is that correct?

Correct, now change the Setup from single coil to dual coil and you'll smile.


28 gauge at 4 volts vapes at about 1 ohm.
Two 1 ohm coils in parallel combine to 0.5 ohms.
That's how you manage to vape 2 ohms of coil at 4 volts, instead of needing 8 volts on a 2 ohm single coil.

 

[jerseyman32]

Gotcha, thanks for explaining it all.

 

[kdubbie]

Thanks everyone for the information ... It's been a big help.

I have another newb question though. So I have heard that if you want to fire a .5 ohm coil, you should have a device that can fire up to 25 - 30 watts. My question is, can't any VV device fire 30 watts? If you have a .5 ohm coil, shouldn't your VV device only need to go up to 3.7 - 3.9 volts to fire at 30 watts with .5 resistance? For example, say I wanted to the throw the Subtank on a simple Ego Twist ... not that I would, but could I? Or will my hand explode ... LOL

Thanks

 

[Ryedan]

Thanks everyone for the information ... It's been a big help.

I have another newb question though. So I have heard that if you want to fire a .5 ohm coil, you should have a device that can fire up to 25 - 30 watts. My question is, can't any VV device fire 30 watts? If you have a .5 ohm coil, shouldn't your VV device only need to go up to 3.7 - 3.9 volts to fire at 30 watts with .5 resistance? For example, say I wanted to the throw the Subtank on a simple Ego Twist ... not that I would, but could I? Or will my hand explode ... LOL

Thanks

Regulated mods are almost always amp and watt limited. That goes for both VV and VW. If they were not you could fry the battery by drawing too much current.

 

[edyle]

Thanks everyone for the information ... It's been a big help.

I have another newb question though. So I have heard that if you want to fire a .5 ohm coil, you should have a device that can fire up to 25 - 30 watts. My question is, can't any VV device fire 30 watts? If you have a .5 ohm coil, shouldn't your VV device only need to go up to 3.7 - 3.9 volts to fire at 30 watts with .5 resistance? For example, say I wanted to the throw the Subtank on a simple Ego Twist ... not that I would, but could I? Or will my hand explode ... LOL

Thanks

1: "Can't any VV device fire 30 watts?"
No.
A VV device will not accept an ohm value that is too low.
Many vv devices will not fire below 1 ohm.
This is to protect from an electrical short.

2: "Could I throw the subtank on a simple ego twist?"
Yes.
You could wrap a 2 ohm 34 or 32 coil on the rba head.

 

[Bunnykiller]

Pink Floyd is kewl....