RBA/RDA Dual & Quad coil builds...but not for sub-ohm vaping

[Libertine89]

Starting getting into rebuilding, nothing against sub-ohm and i will probably give it a go but im just wonder have people put some higher resistance coils into these, especially quad coils to end up with 1.5-2.0 total resistance. I know the equations (as im an electrician) for working out total resitance in parrallel circuits so if you put 4 x 6ohm coils into your quad RBA youll end up with a a 1.5ohm resitance total. Which will keep your amps down and im assuming that four coils will give you more vapour?
Anyone ever tried this or somethign similar with good results?
Also im imagining that using a thinner gauge kanthal is a given so that less wraps are need in the tank to save on space etc.

 

[Susan~S]

Even using 32 gauge wire you will probable run up against "space constraint" issues.

Click on my "signature line" and you can run some numbers using the "Steam-Engine" calculator.

 

[UncleChuck]

The issue is getting the resistance high enough without using ridiculous amounts of wire. Even with something like 34g you're going to have a veeery long coil to reach 6 ohms. That means really slow heat-up times and/or little and cold vapor. You can fix this by pumping more voltage into the build, but then you are dealing with really high power levels anyway, which is the same thing as doing subohm builds.

The point of multiple coils is to get more power, 50 watts on a single coil is likely to burn up, but spread out it works great. If you aren't after high power levels I'd suggest sticking with a single coil, as multiple coils at low power levels is fairly pointless because your coil needs to reach a base temperature to boil the juice properly.

A way to think of it is like boiling water on a stove top. Say you have a pot of water that takes 300 watts to reach a boil. Then you have two pots of water, each one with only a 150 watt heating element. The power is the same, but since those two pots aren't getting hot enough you are seeing much less vapor than you would with a single pot reaching a full boil.

If you plotted power vs vapor production for a given coil on a graph you'd see it's not a linear relationship. In the very low watt range each additional watt adds a lot of vapor, because the coil hasn't reached a proper temp yet. Once you hit the point where the coil is at proper temp, then you see a decrease in the amount of vapor gained by increasing power, this is when it's a good idea to use multiple coils, as that added power is being used more efficiently.

Basically all we are doing is dumping heat into a liquid turning it into a vapor. As long as there is enough liquid available, more power will always give more vapor. Every coil configuration has a point where the wick no longer can keep up to the amount of power being dumped into the coil, and if you want more power/vapor you need to add more coils, so you can see why it's rather pointless to go with multiple coils for low power levels, and in many cases actually hurts performance quite a bit.

To distill all that down a bit, more power, not more coils, will give you more vapor. More coils are simply a requirement sometimes for reaching those power levels.

 

[Libertine89]

Cheers for the posts! yeah i see, im not opposed to high power just dont think my equipment will get there yet, im only on a spinner and aerotank at the moment and will probably be getting a vamo/svd style mod at some point but i realise these arnt high power devices. Ill probably just get a single or dual coil to start with then and practice building coils etc until i can invest in some higher powered mods. ANd going by what youve said its pretty clear you can still get some pretty good vapour off of a dual coil as long as your build quality is good!

 

[Added]

When I first made my switch to solely using rdas I first got an MVP 2 and a Trident clone and started with 1.3 singles. The first coil I made blew me away ( not literally ), and it's been a ride since. MVP and a good little rda can be found fairly cheap, and will serve fine while learning the ins and outs. Good luck and be safe bud.

 

[Fir3b1rd]

When I started on the RDA RBA route I also started with an MVP/kayfun.
The space on the deck isn't exactly conducive to a dual coil; but, I did it anyway and it was great! The trick is making sure you're not using a too much wire. The more wire the longer it's gonna take to heat. I typically run single coil now with 28g round or 30g flat wire. I'm digging the flat as it gives more surface area and takes less wraps so it heads almost instantly.
I'm now using a provari/taifun for my daily runner and WOW-FLAVOR MACHINE!
30g flat wire at 1.5 ohms and it kicks anything else I've tried in the rear. Including RDAs.
I do however run a Poseidon on my stingray at times wrapped at dual coil 0.8 ohm and that's a nice setup as well. I'm just not that huge into dripping other than tasting my DIY juice as it steeps up.

 

[tj99959]

Quad coil builds...but not for sub-ohm vaping

Why would I want to?

This is what a 1 ohm dual coil looks like (2 28ga nano coils @ 2 ohms each)

Looks like a stupid idea, doesn't it.

 

[Byronthecarguy]

I'm running a .06 ohm you heard right 0.06 ohm setup on a dual linear coil using nichrome 26 gauge wire. It's pushing the limits of my IMR MNKE 26650 60a pulse 30a cont. it's in a hates clone with a 28.5 mm Tohb atty. I'm rebuilding the coils for a higher ohm here in a few 0.06 is rediculas and scary I know I'm taking a risk every time I hit it and if you have your hand on the battery vent holes it burns your hand.

 

[ScarletJane]

I would like to build a dual-coil for my RDA that comes out at a total resistance of about 1 ohm. In addition, I'd like to have quick heat up in the coils and have maximum surface area on the cotton wicks. What would you recommend for coil type, coil diameter, number of wraps, kanthal gauge, and horizontal vs vertical coil orientation?

 

[Dogzenkatz]

For a good double or quad coil setup, you would definitely be looking at sub-ohming. 1.2-1.5 micro-coils are typically the best for their efficiency, which you could put down to their number of coils among other things. Even with 2 x 1.8 ohm coils, you are theoretically going to get 0.9 which is in sub-ohm territory. The numbers exist so we may adjust our vapes accurately and monitor our safety. Ultimately, we are after either clouds or flavour. Experiment safely first, the numbers come later!