Resistance and the regulated mod!

[GBalkam]

So it seems to be the popular belief that resistance doesn't matter when using a regulated mod, as long as you are within the mods high and low limits.

Well here's the thing. I just built a massive 13 wrap, dual coil, 24ga nichrome build coming in at 0.48 ohm. Now one would think, since this is a regulated mod, that I could ignore the resistance, right? Well apparently not. I have a 200w mod, and just took the fully charged batteries out of the charger. HG2s I think. (the browns) 20A 3000Mah. Now one would think, being regulated, I could crank that sucker up to 200w and blow clouds that would groud air craft.. not the case. Max wattage I could get was about 140. I know it is in VW mode, since i never use TC anyway. It is a series mod, so pulling 7.2v now at 138w. Just barely over 19A.

Now I also know, since I have been doing it all night, that I can pull the full 200w off a 0.2 ohm build.
This sound about right? The resistance is capping the wattage within the voltage and amperage of the batteries?

 

[Nomoreash]

Would help to know which mod you have but you're correct. Even though a chip may fire a certain ohm range they usually have limits within that range, to get the full wattage out of the chip one needs to build within those limits. Sounds like yours may have a voltage limit around 7v.

 

[GBalkam]

Would help to know which mod you have but you're correct. Even though a chip may fire a certain ohm range they usually have limits within that range, to get the full wattage out of the chip one needs to build within those limits. Sounds like yours may have a voltage limit around 7v.

well I fired it a couple times, 7v was the last reading.
I see people getting into 50 post arguments about resistance not making a difference on a regulated mod. Apparently, it does, since ohms law still applies. Easy to fix, I'll just build parallel coils to get the same wraps at lower resistance to get full power.

7 wraps dual parallel coils will bring me to 0.14 ohms and give me full power. 6 might be better at 0.12, since it will heat faster and not need as much power.
Again, for anyone reading, this is on a regulated mod.

 

[Nomoreash]

Technically it does with most chips but to most people it probably doesn't. I personally can't imagine wanting to vape near 100w or more and many likely feel the same, also they could be talking about the safety features that come with most regulated devices.

 

[APathos]

Yes, it makes a difference in the wattage you can get. It's just a dc-dc converter with an input (battery) and output (tank/deck/coil). You could do the math.

I want 200W to the atomizer (output). So pull 200W from battery (input). I=V/R and P=V^2/R -> solve for R and get R=V/I and R=V^2/P so V/I=V^2/P so I=P/V
I=200/4.2 freshest of batteries - so 47.6A drain. - I just realized I did this on a single 18650 - miracle 50A battery
So running at 200W drains 47.6A no matter the resistance. This assumes 100% efficiency. Which is untrue but used for simplification.

But can the output side deliver the 200W? Say mod limits of 9.3V 60A peak max on a dna250. If we go 1Ohm coil.

I=9.3V/1Ohm=9.3A so sure
P=9.3^2/1=86W so nope. Max watts on a 1ohm coil is 86W.

I think I did the math correct (apologies if not). Or just look at the nice graph evolv did in the spec sheet - dna250

I think the point is that resistance makes no difference in battery drain.

 

[GBalkam]

Yes, it makes a difference in the wattage you can get. It's just a dc-dc converter with an input (battery) and output (tank/deck/coil). You could do the math.

I want 200W to the atomizer (output). So pull 200W from battery (input). I=V/R and P=V^2/R -> solve for R and get R=V/I and R=V^2/P so V/I=V^2/P so I=P/V
I=200/4.2 freshest of batteries - so 47.6A drain.
So running at 200W drains 47.6A no matter the resistance. This assumes 100% efficiency. Which is untrue but used for simplification.

But can the output side deliver the 200W? Say mod limits of 9.3V 60A peak max on a dna250. If we go 1Ohm coil.

I=9.3V/1Ohm=9.3A so sure
P=9.3^2/1=86W so nope. Max watts on a 1ohm coil is 86W.

I think I did the math correct (apologies if not). Or just look at the nice graph evolv did in the spec sheet - dna250

I think the point is that resistance makes no difference in battery drain.

You know, we are talking about a 200w series regulated box mod, right? Right now,pulling 152w at 33 amp and 4.5v or something. The mod is doing the calculations. My other coil was 7.something volts at 19 amp at 140W
coils are 0.13 ohm for this one, and 0.48 ohm for the other one.

But that is kind of what the post is about.. resistance matters on a regulated mod when building cloud chasing coils. (large and bulky). To get max watts output, i have to reduce the resistance, by using quad coils rather than dual. (2x 2wire parallel coils)

There seems to be a lot of misconception that a regulated mod will fire any coil you toss onto it, but that isn't the case, the math still has to work. For example, say 2x 12 wrap coils vs 2x 6wrap parallel coils. Exactly the same amount of wire, same surface area, 1/4 the resistance. Soooo I can use the full 200w at lower resistance, where as the higher resistance is capped around 144w.

 

[GBalkam]

Would help to know which mod you have but you're correct. Even though a chip may fire a certain ohm range they usually have limits within that range, to get the full wattage out of the chip one needs to build within those limits. Sounds like yours may have a voltage limit around 7v.

Oh.. and using an ijoy Asolo 200w mod.
I have fay feng on my facebook. Hoping she can get me an answer about the math and how the chip works from the R&D dept.

 

[Nomoreash]

In the Ijoy Aslo Description on the Gearbest site it specifies a 35 amp and 7.5 volt max output limit.

 

[GBalkam]

In the Ijoy Aslo Description on the Gearbest site it specifies a 35 amp and 7.5 volt max output limit.

Yeah, never had any problem with it. I just found it interesting that many people (and reddit is full of them) seem to be under the impression that building on a regulated mod means you can ignore resistance, and since the mod takes that into consideration and limits output accordingly, that just isn't the case.

 

[KenD]

So it seems to be the popular belief that resistance doesn't matter when using a regulated mod, as long as you are within the mods high and low limits.

Well here's the thing. I just built a massive 13 wrap, dual coil, 24ga nichrome build coming in at 0.48 ohm. Now one would think, since this is a regulated mod, that I could ignore the resistance, right? Well apparently not. I have a 200w mod, and just took the fully charged batteries out of the charger. HG2s I think. (the browns) 20A 3000Mah. Now one would think, being regulated, I could crank that sucker up to 200w and blow clouds that would groud air craft.. not the case. Max wattage I could get was about 140. I know it is in VW mode, since i never use TC anyway. It is a series mod, so pulling 7.2v now at 138w. Just barely over 19A.

Now I also know, since I have been doing it all night, that I can pull the full 200w off a 0.2 ohm build.
This sound about right? The resistance is capping the wattage within the voltage and amperage of the batteries?

You're drawing more than 20 amps per battery at 138w. Around 23-24 amps, assuming a 90% chip efficiency. At 200w you'd be drawing around 35 amps per battery. The battery sag is what's preventing you to go higher, and that's a good thing as it's keeping you safe. Not due to the coil resistance.

Sent from my M7_PLUS using Tapatalk

 

[sonicbomb]

Yeah, never had any problem with it. I just found it interesting that many people (and reddit is full of them) seem to be under the impression that building on a regulated mod means you can ignore resistance, and since the mod takes that into consideration and limits output accordingly, that just isn't the case.

Assuming you stay within the operating limits of the regulating chip, then resistance is reasonably unimportant.
There are still many people who labor under the impression that regulated mods function like mechanicals in terms of the relationship between coil resistance and power. And secondly (and most importantly) how to calculate amp draw on a regulated mod.
When trying to help someone understand something along with a handful of maths to boot, it's best to keep things simple and not further complicate things for them by including additional disclaimers regarding regulator limits and buck/boost efficiencies.

Like KenD said the limits you are hitting are due the limitations of your batteries, and quite possibly the upper voltage limit of your mod.

 

[GBalkam]

Assuming you stay within the operating limits of the regulating chip, then resistance is reasonably unimportant.
There are still many people who labor under the impression that regulated mods function like mechanicals in terms of the relationship between coil resistance and power. And secondly (and most importantly) how to calculate amp draw on a regulated mod.
When trying to help someone understand something along with a handful of maths to boot, it's best to keep things simple and not further complicate things for them by including additional disclaimers regarding regulator limits and buck/boost efficiencies.

Like KenD said the limits you are hitting are due the limitations of your batteries, and quite possibly the upper voltage limit of your mod.

Actually... the mod controller is governed by input values and out put values. Input ignores resistance totally. Now on the output side...
Power = Voltage2/Resistance is used. Now when using high resistance wire, such as 28ga you don't need much power to run the coil. But, when you are building with low resistance wire, and a lot of wraps such as for cloud builds, then the resistance comes into play. Given the controllers output limits, the max resistance you can use is 0.40 ohm to hit 200w on a 200w mod. So to get more wraps and power, you have to lower the resistance. You can do this by adding coils or using parallel coils. (which is basically the same as adding coils). So for example, 2 coil build, 12 wraps of 24ga nichrome = 0.48 ohm at 7v = 144w max but 2x parallel coil (6 wraps parallel nichrome) = 0.14 ohm at 7v = 200w max. (the max the mod can do)
Regulated mods – The Vaporist's Blog
Im a bit OCD, had to find out why my build wasn't giving the watts. lol.
note: I used the same mod and same batteries for both builds.

Mind you , this is really only useful for cloud chasing builds, where surface area and power are the main factors.

 

[GBalkam]

Yes, it makes a difference in the wattage you can get. It's just a dc-dc converter with an input (battery) and output (tank/deck/coil). You could do the math.

I want 200W to the atomizer (output). So pull 200W from battery (input). I=V/R and P=V^2/R -> solve for R and get R=V/I and R=V^2/P so V/I=V^2/P so I=P/V
I=200/4.2 freshest of batteries - so 47.6A drain. - I just realized I did this on a single 18650 - miracle 50A battery
So running at 200W drains 47.6A no matter the resistance. This assumes 100% efficiency. Which is untrue but used for simplification.

But can the output side deliver the 200W? Say mod limits of 9.3V 60A peak max on a dna250. If we go 1Ohm coil.

I=9.3V/1Ohm=9.3A so sure
P=9.3^2/1=86W so nope. Max watts on a 1ohm coil is 86W.

I think I did the math correct (apologies if not). Or just look at the nice graph evolv did in the spec sheet - dna250

I think the point is that resistance makes no difference in battery drain.

Got it. It was the controller output limit formula that needed to be taken into consideration, To max wattage to power huge coils, you have to keep your resistance below 0.40 ohm on a 200w regulated mod. And to do that, we need to add coils to reduce the resistance. So.. in other words, a quad coil with 6 wraps each (24 total) will make bigger clouds than a dual 12 wrap coil (still 24 wraps total) since the quad coil resistance is well below the 0.40 ohms. The 2 builds I am using now are 0.13 ohm quad, and 0.48 ohm dual. Exactly the same number of loops (wraps total). I had to find out how the mod controller was limiting the output.