Question: Current in a Dual Coil Build

[olderthandirt]

Been searching the forums, no luck.
Did extensive googling, got a whole lot of math that simply leaves me in the dirt.

So a simple painless answer would be appreciated (-:

Resistance in a dual coil build is essentially half the sum of the resistance of each coil. Cool, I can handle this.
Two 3ohm coils equals a build resistance of 1.5 ohm.

What I get from the googling I've done is that the current would double? Is that right?

One 3ohm coil at 4 volts would have a current of 1.333 amps.
So a dual build with two 3ohm coils would have a current of 2.666 amps?

If this is correct, hmmmmm.
If this is not correct please be gentle with your laughter. I'm old and frail (-;

 

[Jimi D.]

Been searching the forums, no luck.
Did extensive googling, got a whole lot of math that simply leaves me in the dirt.

So a simple painless answer would be appreciated (-:

Resistance in a dual coil build is essentially half the sum of the resistance of each coil. Cool, I can handle this.
Two 3ohm coils equals a build resistance of 1.5 ohm.

What I get from the googling I've done is that the current would double? Is that right?

One 3ohm coil at 4 volts would have a current of 1.333 amps.
So a dual build with two 3ohm coils would have a current of 2.666 amps?

If this is correct, hmmmmm.
If this is not correct please be gentle with your laughter. I'm old and frail (-;

You are correct

 

[olderthandirt]

You are correct

Really? That in its self is scary (-:

I don't recall seeing this aspect discussed here.

 

[supertrunker]

That is why there's such an emphasis on using the most capable batteries for the loads. Our ol' pal Ohm's law.

T

 

[olderthandirt]

Indeed, I'm getting a much better appreciation for that now.
Prolly not a big deal for me, hard to see me building anything lower than 1.5 ohms. Playing with an online calculator just now and I can see where this is a very real consideration for the sub-ohm crowd.

 

[CloudZ]

As others have said, you are right that a dual coil pulls twice the current of one of its individual coils (provided they are the same resistance, which is what you want). They also consume twice the power of one of the coils individually, but a better way to think of this is that each coil consumes half of the total circuit power. Ohm's law is pretty simple, you should be able to use any calculator for it.

I = total circuit current in amperes
R = total circuit resistance in Ohms
W = power in watts

V = I x R
I = V / R
W = I x I x R = V x V / R

For a simple circuit of parallel resistors (coils):
1 / R = 1 / R1 + 1 / R2 + ...
R = 1 / (1 / R1 + 1 / R2 + ...)

For a dual coil, if R1 = R2:
R = 1 / (1 / R1 + 1 / R1) = 1 / (2 / R1) = R1 / 2

Hopefully the notation makes sense, and sorry if this was obvious/unnecessary info.

 

[BobC]

You had ta go do it, hah? You had to ruin everything by posting math, Jeeeeesh!

 

[olderthandirt]

While I can almost visualize the idea behind the resistance being half the sum of the two coils my mind just has to except on faith that the current doubles.

Sadly Cloud, the math does me naught.
Algebra and I have been and always will be I fear, strangers )-;

 

[Thrasher]

While I can almost visualize the idea behind the resistance being half the sum of the two coils my mind just has to except on faith that the current doubles.

Sadly Cloud, the math does me naught.
Algebra and I have been and always will be I fear, strangers )-;

in simple terms just use the ohms law calculator and remember it isnt what the coils are individually it is what the resistance is at the 510 connector that matters.

if you use (2) 3ohm coils the resistance is 1.5 that is the number you need to worry about. if it is (2) 1.4 ohm coils the total is now .7ohms that is what you use to calculate.
it is true the current doubles but in simplest terms it is only because the resistance is cut in half. lower resistance= more power

resistance is absolute. doesnt matter if it is 1 coil, dual coils, quad coils, 20 coils. to the battery 1 ohm is 1 ohm and when calculating current draw that is all that matters. what the battery sees at the 510.............(now how that affects vaper is another thread so)

 

[olderthandirt]

... it is what the resistance is at the 510 connector that matters.

...it is true the current doubles but in simplest terms it is only because the resistance is cut in half. lower resistance= more power

...when calculating current draw that is all that matters. what the battery sees at the 510.............(now how that affects vaper is another thread so)

Thrasher got it done, parted the clutter in my foggy brain and I thank you.

Amazes me the difficulty I have at times in seeing the forest for the trees!

 

[CloudZ]

While I can almost visualize the idea behind the resistance being half the sum of the two coils my mind just has to except on faith that the current doubles.

Sadly Cloud, the math does me naught.
Algebra and I have been and always will be I fear, strangers )-;

Just think of it as two parallel water hoses. Input water pressure is the voltage, the water flow volume is the current, and the fluid friction (resistance to flow) is the electrical resistance. This all holds true for wider hoses (thicker wire) reducing resistance and longer hoses (more coil wraps) increasing resistance. These things are inversely proportional to water flow volume (current). Two equal hoses in parallel will have half the resistance and twice the flow volume as each of the single hoses.

 

[olderthandirt]

LOL, Cloud I can be deemed hopeless at times.
The water hose analogy has never worked for me. It's been before my eyes many times over the years, my brain refuses to see it. )-;

Thrashers post just back a couple did work for me though, can't say why but it did!

Please don't give up on me in the future though!!! (-:

 

[CloudZ]

LOL, Cloud I can be deemed hopeless at times.
The water hose analogy has never worked for me. It's been before my eyes many times over the years, my brain refuses to see it. )-;

Thrashers post just back a couple did work for me though, can't say why but it did!

Please don't give up on me in the future though!!! (-:

Its all good. As long as you know the basic idea, you at least know there is something to be considered. Visualization of electricity can be difficult for a lot of folks, it was difficult for me as well until drilled into my brain in Electronics 101. I'm glad I went on to a mechanical field of study though, since the higher level electrical stuff always baffled me and still does.

 

[whoaitsruss]

Been searching the forums, no luck.
Did extensive googling, got a whole lot of math that simply leaves me in the dirt.

So a simple painless answer would be appreciated (-:

Resistance in a dual coil build is essentially half the sum of the resistance of each coil. Cool, I can handle this.
Two 3ohm coils equals a build resistance of 1.5 ohm.

What I get from the googling I've done is that the current would double? Is that right?

One 3ohm coil at 4 volts would have a current of 1.333 amps.
So a dual build with two 3ohm coils would have a current of 2.666 amps?

If this is correct, hmmmmm.
If this is not correct please be gentle with your laughter. I'm old and frail (-;

So than not mistaken... four 3ohm coils would be 5.332amps and .75ohms???



Sent from my iPhone using Tapatalk

 

[MorpheusPA]

The math can be painful. Visualizing it, not so much.

1) You have one 3 ohm coil, for the sake of argument. Power flows out of the battery, around the loop of the coil (generating heat) and back to the negative post of the battery (actually, no, but this is conventional diagrams we're talking about so let's just run with it).

That single loop uses a given amount of wattage, whatever it is.

2) You have two 3 ohm coils. Power flows out of the battery, and through each loop separately. Since nothing is different, and there are two paths for the power to take, you use double the wattage.

3) You have X 3 ohm coils. Power flows through X loops. You use X times the wattage of one coil.

Electricity doesn't get confused and go the wrong way, or stack up like a traffic jam (under normal circumstances), so you'll always follow very precise math and a very logical pathway.

You could theoretically even have two different loops of two different resistances. Just calculate each separately and add them together to get the total power. We do the same thing to figure out the total energy used in an electronic circuit, which can have many different pathways of many different resistance measurements. The little electrons figure it all out.

 

[MorpheusPA]

So than not mistaken... four 3ohm coils would be 5.332amps and .75ohms???

Sent from my iPhone using Tapatalk

Exactly. 8 coils would be 10.67 amps and 0.375 ohms, and so on.

Other than size, convenience, and the limits of what a battery can supply safely, there's no reason you couldn't make an atomizer with as many parallel coils as you wished. Powered from a properly chosen plug in transformer, only size and convenience would matter.

 

[olderthandirt]

... always follow very precise math and a very logical pathway. ...

My math and logic and visualization centers have been out for repair for a long time sad to say.

)-:

But I do have enough info to wing it safely (-:

ETA: The ongoing illustrations and explanations should be invaluable to other noobs though! (-:

 

[MorpheusPA]

My math and logic and visualization centers have been out for repair for a long time sad to say.

)-:

But I do have enough info to wing it safely (-:

ETA: The ongoing illustrations and explanations should be invaluable to other noobs though! (-:

It's all good!

It might be easier to think of it as a 1 lane highway (single coil) or a 2 lane highway (dual coil). The cars can only move at exactly a given speed (determined by the voltage). Unlike real life, there should be no laggards, accidents, road closures, or on/off ramps to mess things up.

Given that, the 2 lane highway (the dual coil) can pass twice as many cars in the same time. And each lane will accommodate exactly the same number of cars per hour as long as they're identical. When the cars reach their destination, or the coil, they do some work and then drive back home.

Of course, the battery only has so many "cars" in it, so sending twice the number down the two pathways will drain the battery of cars twice as fast.

Some of us like 1 lane highways, others like 2 lane highways. Both work fine and get you where you want to go, however.

 

[olderthandirt]

he-he
By damn that one sank home Morpheus, LOL.

I read your analogy, it made perfect sense and now I've an urge to dig out an Eagles CD and listen to "Ol' 55".

"And now the sun's comin' up
I'm ridin' with Lady Luck
Freeway cars and trucks "

 

[MorpheusPA]

It's amazing how often car analogies work with people. We've all driven down a highway and realize that a four lane highway accepts far more cars moving at the same speed than a two lane, and so on.

Now just realize that each car is an electron (actually, a propagation wave, but it's not that important) and you link right back to the battery and what it's doing.