1st build: 0.85ohm @ 50w??

[Rednaxela1987]

Hey everyone, just got my Hellboy rda in the mail from @skullblade789 (thank you so much!!) and I put my very first ever build in it today. I only have 30g Kanthal (didn't want to mess with the Ni200 yet) so I did a 7-8 wrap 2.5mm dual coil build and it comes out to 0.85ohm.

The weird part is it does not give a good vape until 45-50w, and even then almost feels a bit under powered. Is this normal? I would have thought a build of this resistance would only need 30w or so. Is there something I am forgetting? Either way it vapes pretty nice, but not much vapor production, I think because my coils are not very tight.

I am so excited to get into building, I love tinkering and mathematics so I just know this will be a blast.

Sorry there are no pictures, my smart phone is broken at the moment until I get a new LCD screen for it.

 

[billgharley]

If you do spaced coils, and make sure there is space between every single wrap, then you avoid having potential hot spots.
If you do touching coils, you should fire the coils (with Kanthal only) without cotton and make sure you don't have any hot spots. Typically when you fire/pulse the coils and get them hot, you'll see parts of the coils that are not firing evenly. Use some tweezers or pliers and gently squeeze them together. Keep doing this until the coils fire and glow from the inside out.
Cotton should be not too tight and not too loose. Tight enough to cause some resistance when pulling back and forth in coil.
On my dual coil Billow v2 I can vape a .85ohm at 30-40 watts and get a warm and tasty vape with great flavor. But, we all have our personal preference and do what works for you. Some like a cooler vape, some like a nice hot one.

 

[Rednaxela1987]

If you do spaced coils, and make sure there is space between every single wrap, then you avoid having potential hot spots.
If you do touching coils, you should fire the coils (with Kanthal only) without cotton and make sure you don't have any hot spots. Typically when you fire/pulse the coils and get them hot, you'll see parts of the coils that are not firing evenly. Use some tweezers or pliers and gently squeeze them together. Keep doing this until the coils fire and glow from the inside out.
Cotton should be not too tight and not too loose. Tight enough to cause some resistance when pulling back and forth in coil.
On my dual coil Billow v2 I can vape a .85ohm at 30-40 watts and get a warm and tasty vape with great flavor. But, we all have our personal preference and do what works for you. Some like a cooler vape, some like a nice hot one.

Yeah I pulsed them and they were pretty even, glowing from inside out. Thanks for the tips!!

 

[TheKman]

Input power is only relevant to the quantity of juice you need to heat and the air that flows. The actual impedance of the coil is irrelevant, only the surface contact area matters.

So, if it's well spaced, a dual coil of 8 wraps @ 2.5mm would require about 50W to produce reasonable vapour. Ni, Ti, Kanthal, SS... The different materials determine surface area, impedance and electrical characteristics. The goal is to tune for contact area, juice flow and air flow, not impedance.