Dual Coil Issue

[lopenator]

Hello ECF Community. Recently I have been triying to play around with dual coils. EVERYTIME I build one, my Vamo is always reading 1 OHM, which it cannot vape at. What is the most effective way to make it higher? Should I just wrap the coil like 9 times around each one? Make the coil larger in perimeter?

Edit: BTW this is in my Aerotank. Even when I was doing in it my IGO-L, it was still always readig 1 OHM. The both positive ens are suppose to be touching and the both negative ends are right?

 

[WileECoyote]

Yes, more wraps or larger mold. Make sure they are both equal.

 

[lopenator]

Okie Dokes. Whats the worse that'll happen if they are not equal? What if they're off by like .5?

 

[WileECoyote]

They wont heat evenly.

 

[lopenator]

Thank you for your input kind sir/madame.

 

[WileECoyote]

All good, I am a dude. That is why ECF is here.

 

[lopenator]

Ok, I just re-built it. It now reads 1.4 Ohms. When I set my volts to something low like 3.5. It takes a long time to turn red. I figured low volts was good for 1.4. Should it be higher? Do the same rules apply to dual coil as single?

 

[WileECoyote]

On dual coils the same voltage drops over each coil the circuit resistance is the average of the two. so the current is higher but the coils will take longer to heat up. You should up the voltage but keep in mind the current is going to be A=V/((R1+R2)/2) if that makes sense. I am unsure if your mod is regulated or if it is mechanical.

 

[WileECoyote]

Simple parallel circuits : Series And Parallel Circuits

 

[lopenator]

its regulated. im rocking a vamo.

 

[WileECoyote]

Hopefully someone comes by and puts they specs up for you. I don't know them off hand and am at work right now.

 

[DKP#]

A=V/((R1+R2)/2)

That's incorrect sir.
A=V/(R/2)

For parallel resistances of the same value:
Rt = R/N
or R_total = R_each / Number_of_coils

For 2 unequal resistances: product over sum
Rt = (R1 * R2) / (R1 + R2)

For any number of parallel resistances, add the conductance's, then invert
Rt = 1 / [ (1/R1) + (1/R2) + (1/R3) ...]

 

[DKP#]

Do the same rules apply to dual coil as single?

With a Voltage setting(or a mech), They behave as 2 completely independent coils.
With a Wattage setting, the power is divided between coils so the power that one coil uses will be 1/2 of the setting.

 

[WileECoyote]

That's incorrect sir.
A=V/(R/2)

For parallel resistances of the same value:
Rt = R/N
or R_total = R_each / Number_of_coils

For 2 unequal resistances: product over sum
Rt = (R1 * R2) / (R1 + R2)

For any number of parallel resistances, add the conductance's, then invert
Rt = 1 / [ (1/R1) + (1/R2) + (1/R3) ...]

Sorry if I was but when I am sober, I will check this and my math... I think I was trying to be too simple. Hate that I was wrong cause I did learn DC theory but that was 16 years ago.

Sent from my DROID4 using Tapatalk

 

[WileECoyote]

Wait a sec, I was right, he had 2 coils... so I was saying the average. Wrong is such an absolute word, sir.

if I make 2 coils of the same resistane, I take the average of the coils to be Rt. Then use ohms law of E=IR to figure the rest.

Sent from my DROID4 using Tapatalk

 

[GeorgeWachsmuth]

I rebuild my Aerotank with single coils and cotton. Works great....1.8 to 2.2 ohms....

 

[UncleChuck]

Wait a sec, I was right, he had 2 coils... so I was saying the average. Wrong is such an absolute word, sir.

if I make 2 coils of the same resistane, I take the average of the coils to be Rt. Then use ohms law of E=IR to figure the rest.

Sent from my DROID4 using Tapatalk

He said you were "incorrect" which technically you were The formula you gave is only correct if the two coils are of the same resistance. If they are of a different resistance you can't just divide by two (taking the average) you have to divide by the sum of the two resistance values.

Example to illustrate the difference in answer:

-Uneven dual coil with 1 ohm and 2 ohm coil-

A. If you just take the average you get (1+2)/2 or 1.5 ohms

B. If you use the proper formula you get (1*2)/(1+2) or .67 ohms

As you can see it's quite a large difference in resistance, if you have unequal coil resistances and just take the average it's possible to get into a dangerous situation thinking your resistance is a lot higher than it actually is.

 

[DKP#]

Parallel:

 

[Dampmaskin]

Since your dual coil build is 1.4 Ohm, your coils are 2.8 Ohm each. So set your volts for 2.8 Ohm. That will give you the same vape as a single 2.8 Ohm coil, only double, if you get my drift.

In practice you will probably want to go a little bit lower than that, but not as low as for a single 1.4 Ohm coil.

 

[WileECoyote]

I love this place. No offense taken.

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