How to build 200w coils?

A 0.4 ohm build at 9 volts would give you 202 watts while pulling 22.5 amps. I don't know for sure but some are saying the max amp limit on the RX200 is 23 amps and some are saying 25 amps. Either way you should be able get to 200 watts with a 0.4 ohm build.

 

.25r @ 200W only draws 7V but the amps are higher than above. I would look at your mods specs to get the correct ohm range that allows 200W vaping. anything else is nothing but guesswork

 

Makes sense

Was unable to find decent specs for the mod when I wanted to know it's weight without battery. If they are available then would help, otherwise it'll have to be guesswork.

In any case, what I'm seeing from you and lotta have said, is the ohm range will probably be between .25 and .4 which is pretty specific.

So thanks guys, you've helped me narrow it down.

A 26/32 Clapton around 4 or 5 wraps came out at around .4 ohms for me, so four coils in parallel may drop the resistance too low. So I might try more wraps to up the inividual resistance, and ID I think also factors in determining the final resistance. But I think I'll start around 3 or 3.5mm for convenience for ID as I'm already tooled for it.

 

4 of those coils exactly the same will come in @ .2 ohms if 2 are .4 ohms. Should be Ok for the mod around there as well subject to the amp limit of the chip. Simply a multi coil build is the ohms of a single coil divided by the number of coils fitted.

ID has an effect on the final resistance of the coil because it takes a longer length of wire to make the same number of wraps and so increases the Ohms of the coil.

3mm should be ok up to around 120W or so but after that you will need the extra wick inside the coil that a larger ID supplies to keep the juice up to the coils.

If you're not getting the wicking you think you should I found that making the wick tighter inside the coil helped with that as it kept a good contact with the wire. Just make sure the tails are fluffed out a bit to allow the juice to flow quickly up the wick.

Not sure what VG ratio you are using but the throat hit on much less than 70-80% VG is going to be a lot more noticeable as you get higher Watts to the coil.

 

200 watts and staying at 23 amps with a voltage of 9 volts or less will need a coil between 0.38 ohms and 0.4 ohms. Any higher and you will exceed the voltage limit. Any lower and you will exceed the amp limit (if it is indeed 23).

 

You're a legend mate, I have a few innovative ideas of my own, so see what I can put together.

Throat hit, well I can chop and change the juice to suit, but thanks for the tip ...

Lotta's calculations below look sound to me, for series batts 9v is closest to the real voltage of the series batts, which I think may put the least strain on the mod as the least work done in changing voltage. Guesswork I know !

I'll check my existing clapton coils, check the parallel resistance calcs etc, and work on that basis. What you said I think is correct, might be prudent to aim for the lower ohm, to make sure full 200w is available, if I ever get a coil with metal to soak up the watts built, we'll see ... Watch this space ...

**Updated**

PS, I'm considering mounting the coils vertically in the RDA, do you guys have any tips on wicking in this scenario, basically I think inner wicking, but can't figure out what to do with the top part of the wick. One idea would be to "droop" them back in the Center of the deck to touch the base of the RDA.

PPS @Longtail1 mentioned a chuff cap, from what I can see on Google that's just a wide bore drip tip ?

**Updated**

PPPS, sorry guys my ohmage estimate was way out for single coil Clapton 26/32, 5 wraps ID 3.5, I now see 1.16 ohm on my mod ... Doh !

**Updated**

PPPPS, just checked a few coils of varying ohmages on the rx200, and build must be sub 0.4 ohm, just to select 200w on the mod ... For instance it reads 8.99v/ 192w(max) @ 0.42 ohms

 

So, with my own planning, research and help from you guys it wasn't actually that difficult. Steam engine wire wizard is awesome for planning coil builds.

I decided to go with vertical coils, as spitback then could be pretty much eliminated, no mouthfulls of molten lava with this one !

Dual parallel 26/32 kanthal claptons ID 5mm, 6 wraps provided the correct target resistance, I ended up with about 0.33 ohms. It fires at 8 point something volts @ 200w. The build I did in my velocity RDA, ideally a larger build deck 24mm RDA or larger might be preferred, but I like challenges, so went about as big as possible in velocity without touching the sides. Also perhaps some kind of 510 to 510 heatsink to protect the mod a little from any conducted heat, might be a nice addition.

Wicking was pretty simple, about 15mm off of a cotton sheet, roll into tube, twist the tube, then twist the wick into the coil until it hits the bottom of the RDA's well. Then cut off the cotton very close to top of the coil. Saturate with juice and fill the juice well. You're ready to go at 200w.

Things do warm up pretty quickly @ 200w, the outside of the RDA, and the mod circuitry including the fire button. The VTC5s didn't actually seem to blink an eyelid, staying relatively cool.

Clouds @ 200w, biggest clouds I've ever vaped, pretty warm, but not hot hot. For me personally, larger clouds than I need, but I have proven to myself that the RX200 does what it says it can, which was what I wanted to know.

The build will obviously fire and work fine at lower wattages, tested at 150w, and, maybe that's a better vape, I dunno ...

Here's what I ended up with :



One last tip if you're ever building something similar - I found it easier to work with the coils by first forming the coils, then annealing them with a blowtorch, then final adjustments fitting them etc. This I think is because the wire becomes less "springy" in the annealing process, so easier to form the coil, and shape it's legs.

 

How's the flavour up there?

 

Some long legs on them,how many mil of juice they take?

 

I must admit I am a little confused about the way you attached the coil leads. Am I looking at the picture wrong? Am I missing something?

 

LOL, prefer it lower on the watts, little bit cooler, if I'm honest. Was gonna do a separate post on that, so I will do, to explain what I think in more detail.

I think fully loaded it only 2ml ish, I didn't measure. At 200w it doesn't last long at all, few pulls then juice well is empty and wick starting to get dry.

You didn't miss anything, in fact that is very pertinent question. Each coil has one leg mounted on it's "own side" and one leg mounted on the opposite side. I did it like this because the coil simply was too tall for the posts, and I was starting to get the leg leads interfering with the coils.

So the legs at the top cross over to "the other side". There was just about enough space in the top of the RDA with cap on to accommodate the whole thing.

Also to note is that the bottom of the coil dips quite far into the juice well, there's only a mm or two between juice well base and coil.

 

That explains my confusion. I couldn't figure out why the leads went over the top. It looks like you will need larger gauge claptons so you can do fewer wraps. It should help out with the space issue and allow for more airflow. As a side note to anyone that owns a Velocity RDA. The bottom airflow holes are 10 mm X 2.5 mm. I wanted more airflow without using the upper airflow holes. I had the bottom holes machined out to 12 mm X 3 mm. The available airflow increased substantially without cutting down on flavor. It's almost like a different RDA. For anyone wanting to make this modification, 3 mm tall almost touches the top airflow holes and only lets you just catch the threads before it starts closing the airflow. 12 mm lines up perfectly with the spacing on the top airflow holes. The edges of the bottom airflow holes are even with the outside of the 2 top airflow holes. You could go wider than 12 mm if you wanted to but there is more than enough airflow for me.

 

the current setup is as far as I'm going right now with high watt builds. But yes, I'm sure there's a wire way to reduce the coil height, I like the idea of fused claptons but don't have the raw materials to make. Maybe dual 24g wrapped with 36g or higher. It was suggested to use nichrome for the cores and kanthal for the outers, to keep the resistance low, but I don't have those materials.

The post hole size becomes an issue with larger gauge wire, and I wasn't sure whether one could strip the claptoning off at the post holes to get wires in there or not, I suspect it is. However didn't want to create a weak point that would heat up, and didn't need to in the end, dual 26/32 claptons fit in my post holes.

I did use the upper airflow holes, because the coil is adjacent to them. But do see the point, more airflow may be preferable, especially if it's still adjustable downwards.

At the end of the day there's a maximum volume of vapour that one can draw in in one blast, so more airflow just means a shorter burn, which would also perhaps be a little cooler. Probably !

PS ...

@peter-k I just did some more testing with a DIY mix I'm working on, flavour off that was very nice actually. I did a separate post to explain why I think more watts, doesn't necessarily mean more flavour.

 

Yes that's why I asked. I sure will read what you gotta say about it.

 

Just posted it here - E-Liquids - The Law Of Deminishing Returns | Thailand Vapers

**Updated**

UPDATE - so I've had more time to try this build out with different liquids and wattages.

It's actually grown on me. 200w is the upper end of power for this build, happier vape @ 170w. At 100w it's starting to not work so great. 200w the case for the RDA is warmer than "comfortable".

To refill it's probably only 0.5-1ml to "refill" the wicks and the well. Then probably 3-4 blasts before refill again.

@Longtail1 advice about throat hit was pretty much spot on. So either expect, and get used to a heavy throat hit, to use higher VG liquids.

Flavour works well @ 170w or 150w