RDA duel coil issue

[dapper]

So first I have been rebuilding my own coils for a while now.

Anyway, I was originally building on a smok Caterpillar when it was first happening. Every time I installed duel coils, I'd get a dead short (shown by 0.0ohms on my temporary ohm reader, my mvp2.0 lol). But single coil works great. I recently picked up a Cigreen Zenith v2 clone and I have the same issue. I've wrapped many many many coils and never had an issue until recently. I don't really think it's the MVP breaking on me because if a single coil is installed it reads ohms perfectly fine. Only when duel coils installed, does it indicate a dead short. One of the times i did just attempt to pulse fire a build (galileo with the zenith v2) and it shorted and popped the kanthal right at the posts. Im not entirely sure if its something stupid im subconsciously doing differently but I have a feeling it is. No part of the kanthal is touching the deck, chamber, posts(that I can see atleast), or other kanthal. Im just curious as to what the possibilities are that I might be doing wrong that I don't notice.

For the record, I am using 28g kanthal. And on occasion, 26g.

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[Baditude]

You didn't mention at all what resistance coils (ohm) you were attempting to make. This is important to know to troubleshoot your problem.

Did you make the same ohm for your dual coils as you did the single coil?

Say for instance you were making a 1.2 ohm single coil before. To reach an overall 1.2 ohm dual coil build, you would need to make two 2.4 ohm coils. This is Ohm's Law.

Play around with this Coil Toy Calculator. Type in the appropriate info in the drop down menus and learn how many wraps for a particular resistance coil. Provides a graphic of how the finished coil should look. Try this with both a single and dual coil build.

Your MVP metering 0.0 ohm indicates either a dead short in your build, or the MVP is not capable to read sub-ohm builds. If you made two 1.2 ohm coils, their overall resistance would be 0.6 ohms (sub-ohm territory).

Get yourself an ohm reader box.

 

[Andrew1919]

If you posted a picture of one of your builds that would be very helpful. You also mentioned you were using an mvp. Make sure you do not go below the 1 ohm on an mvp, or you will have issues. What was the resistance of this build? Also, make sure the screws in your posts on your rda are tightened all the way down. If they are not tight, it will not make a good connection. I also don't know how many wraps you are doing, or what you are wrapping around, but in general a 26 gauge or 28 gauge dual coil will definitely be too low resistance for an mvp. that could be the problem.

 

[DetraMental]

I have to be extra careful when wrapping dual coils in that they both have to be identical in the way they are wrapped. You may already be doing this but that was my problem when I first tried to do them. Also, as was pointed out, you gotta keep the ohm above 1.2 so you'd need to make two 2.4 coils at minimum for an MVP to read it.

 

[dapper]

Sorry about that. Should've been more specific. Lol I only use the MVP to read to ohms temporarily. I use my Galileo with EH IMR 30A discharge 18650's 1600mah. And it does it with all. But to be more exact. Its done it with a pair of micro coils, nano, and super nano with 28g. Typically I do anywhere from 8-12 wraps depending on the diameter of the wraps. Yesterday I wrapped a super nano with 28g at 8 wraps that came out to about 0.6ohms for either coil individually, 0.3 for both. And I understand ohms law. I've been rebuilding for a bit now and I know how to do this safely and understand ohms law and so on. And I won't go any lower than 0.2 ohms at the very most due to the crazy amount of amps its drawing from the battery. I was just looking for advice to try to figure out what Im doing wrong/different that im stupidly not noticing.

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[Andrew1919]

Sorry to hear that you are having trouble. if you posted a picture of your build here, that would be the most helpful thing. The only other thing I can say is make sure you have a good connection between atty and mod, make sure your coils don't touch the deck, posts, top cap of your atty, or leads from the other coils. they should be touching absolutely nothing. the other thing you could try is making a dual coil out of a single strand of kanthal. so instead of making two separate coils, and then installing them on the atty, make one coil, with one very long lead. Install this coil normally, and then (with the long lead going through the center post) wrap another coil out of that lead, and then finish by fully installing this second coil (putting the remaining lead on this second coil through the other negative post). I say this because maybe the two strands of wire through your center post are causing the issue. that is my best guess at this point.

 

[Baditude]

According to my calculations, a 0.3 ohm overall target resistance using 28 ga Kanthal wrapped around a 2mm cylinder would need 5 wraps for each coil.

 

[dapper]

Thanks for the replies. I've always got in the habit for checking every bit of the kanthal to look for any shorts. It always just breaks off at the posts. Which is why im sure its something stupid im not noticing. But both coils are the exact same amount of wraps, resistance and both have no hot spots or are making contact with any part of the Atty. But yeah I took 28g and did 8 wraps around some 28g kanthal and it came out to 0.6ohms for that one coil.

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[Saltraker]

Baditude....you are a fount of information. I never heard of Coil Toy, so I went and looked at it. At last, I can see how you get the coil leads going in the same direction! I've book marked Coil Toy and will be referring to it often. There's a note on the page that a mobile version is coming...do you know if it's available or not? Thanks for the info.