Mech mod dimension question?

[C3RB3RU5]

So I couldn't find anything on the subject so I come in search of an answer. When designing a mechanical mod, does it matter what your dimensions are aside from battery volume and the 510 threading? What I'm getting at is does the amount of metal, thickness, volume, length, etcetera, have any bearing on the resulting or end wattage/voltage/resistance of the mechanical mod? What is the typical mech mod wattage? I thought I read somewhere it was around 30-35 watts?

Maybe the reason I didn't find anything on the subject means it doesn't matter, after all, mechs come in many different designs, shapes, thickness. Just wanted to make sure before designing one. Any advice would be appreciated!

 

[vapero]

on a mech mod the wattage will be set by the resistance of your atty., your battery will give you 4.2 fresh and begin to drop off as you vape...
it could be anything from 120w to 10w
that said it's all about voltage drop; the battery voltage as it moves from the bat to the coils on it's path it could waste a bit depending on the path (if a spring is part of the current path it could loose a bit, if the threads aren't perfect it could also loose a bit and so on), so if you start with 4.2 coming from the bat but only be reaching 3.8v on the coil...

the rest doesn't really matter

 

[C3RB3RU5]

So what your saying is the voltage drop, depending on metal thickness or length the current has to travel, will only change a negligible amount? Also can you give an example of what you mean by "wattage will be set by the resistance of your atty", given said resistance say .3 Ohm? Is there an equation to use? Or maybe point me in the right direction so I can figure it out. Thanks for your input so far.

 

[vapero]

Ohms Law Calculator
if you are using a .3ohms (hope that was a typo and your not trying to vape at .03ohms)
you will start to vape at 58.8w (4.2v of the fresh battery) and end up at 43.2w (at 3.6v of the drained battery) that is not taking into account the voltage drop
some info on voltage drop Voltage drop explained? | E-Cigarette Forum
but the -drop doesn't really matter that much (until it is too much) so don't be that concerned

 

[C3RB3RU5]

Basically all I really need to know is do I have free range to design a mech mod with only battery size and a 510 thread on top in mind? Designing one in any shape, thickness, etc? I know different materials conduct electricity differently. Will the result be a properly functioning device? I'm thinking it can't perform too well in terms of conductivity. I just want to be able to work one up in CAD/CAM software and send it to a prototyper to be made. So I would not be able to test voltage drop with an atty until after I had it made. Plan on using this mech mod with atty coil builds of as low as .2 - .5 Ohm if that helps any..

 

[C3RB3RU5]

Ohms Law Calculator
if you are using a .3ohms (hope that was a typo and your not trying to vape at .03ohms)
you will start to vape at 58.8w (4.2v of the fresh battery) and end up at 43.2w (at 3.6v of the drained battery) that is not taking into account the voltage drop
some info on voltage drop Voltage drop explained? | E-Cigarette Forum
but the -drop doesn't really matter that much (until it is too much) so don't be that concerned

Yes sorry .3 Ohm not .03 that wouldn't be a good time! (will edit previous post) And this is perhaps a stupid question but I was just reading that "It’s recommended to vape the Aspire Atlantis between 35 to 40 Watts" but I'm assuming based on the information you gave, that figure changes depending on the pre-built atomizer resistance that you use? Like my version 1 Atlantis comes with .5 or .6 ohm atomizers and I believe the V2 Atlantis goes down to .3 ohm ones. I would like to be able to use both the Atlantis on occasion as well as RDA's. And thank you for your quick response and your help!

 

[vapero]

just take a look at my avatar or see my blog, all those bare bone mechs work really great and don't notice the voltage drop, so anything you design shouldn't really have a problem on that department (unless you paint the threads and cut the flow of electricity you'll be fine)

a lot of people swear that the material makes a huge difference in voltage drop as some are more conductive than others (copper > aluminum > brass > stainless steel)
but from my experience my best hitting mod is my ss smpl, works better than my brass mods, as it is a single tube without a lot of threads and an integrated hybrid 510, the current goes almost unrestricted

 

[sonicbomb]

I beg to differ on what vapero says about SS vs copper. Copper is a better conductor of electricity than steel. I would like to put a SS SMPL and a copper SMPL side by side with identical loads and test the drop. My copper SMPL comes out to 0.17 volts dropped at a 0.6 ohm load. I also modded my SS Panzer with internal copper tape, and the drop went from 0.7v to 0.3v.

From what I have read, the main factor in loss of efficiency is where metal touches metal. For example the threads, the switch and the 510 connector. Particularly the threads where there are multiple points of contact where micro-arcing can occur. If you imagine where the threads intersect, there will be a point of contact, then an area where the two surfaces part leaving a small gap that electricity can jump across. This can be mitigated using a Noalox or a similar product, and by having well machined threads with tight tolerances. Some people deny that Noalox works. I have tested mods before and after treating and seen a significant difference in voltage drop. I also had a Sigelei 30W tube mod, where the bottom battery cap would get significantly hot during use. I applied Noalox, no heat, ergo it must have been suffering from severe micro-arcing.

This is also why hybrid connectors increase efficiency as you are eliminating multiple parts and points of connectivity by connecting the battery positive directly to the atty.

 

[vapero]

I beg to differ on what vapero says about SS vs copper. Copper is a better conductor of electricity than steel. I would like to put a SS SMPL and a copper SMPL side by side with identical loads and test the drop. My copper SMPL comes out to 0.17 volts dropped at a 0.6 ohm load. I also modded my SS Panzer with internal copper tape, and the drop went from 0.7v to 0.3v.

From what I have read, the main factor in loss of efficiency is where metal touches metal. For example the threads, the switch and the 510 connector. Particularly the threads where there are multiple points of contact where micro-arcing can occur. If you imagine where the threads intersect, there will be a point of contact, then an area where the two surfaces part leaving a small gap that electricity can jump across. This can be mitigated using a Noalox or a similar product, and by having well machined threads with tight tolerances. Some people deny that Noalox works. I have tested mods before and after treating and seen a significant difference in voltage drop. I also had a Sigelei 30W tube mod, where the bottom battery cap would get significantly hot during use. I applied Noalox, no heat, ergo it must have been suffering from severe micro-arcing.

This is also why hybrid connectors increase efficiency as you are eliminating multiple parts and points of connectivity by connecting the battery positive directly to the atty.

you are totally right, I didn't made myself clear, two exact setups just changing the material the copper is better

(copper > aluminum > brass > stainless steel)

but I was making the point that voltage drop tends to be more noticeable badly done threads and connections than the one intrinsic from the material used. of course there are better conductors but you can get better conductivity from a well machined ss than a bad machined copper

 

[sonicbomb]

Agreed. I suppose a pure 24 carat gold mod would be the ticket

 

[C3RB3RU5]

Both of you have helped immensely with the information you've provided. I wouldn't have thought the threading, buttons, pins would have a greater impact of the conductivity than the material properties themselves. That being said it does seem to make sense. I will take both the material choice and spark gaps into consideration.

I guess another question would be whether fine threading or course threading would be a better choice, given that both are machined to tight specifications. I would think fine threading because of the fact fine threads have more teeth and in the use of threading for water fittings more threads per inch mean better sealing properties. Better sealing properties=Better conductivity=Less spark gaps.
I have seen threading on mechs both fine and course and wonder the pros and cons other than the speed at which one can screw on the end caps.

I suppose a pure 24 carat gold mod would be the ticket

To my surprise pure gold is actually one step behind copper in terms of the conductivity of metals sorted by resistivity. Apparently according to the charts pure silver is the best material in this scenario. However pure Ag or Au would be awfully pricey and terribly soft for a mod body.

 

[sonicbomb]

Gold is used not just because of it's conductivity, but it's well known resistance to oxidation which in turn means that it continues to conduct well over time.

As far as the thread size (this is pure conjecture):

Micro-arcing would occur over gaps of a few 10ths or 100ths of a millimeter so within the this context big or small threads would be irrelevant. Small threads would be less resilient to damage and wear than large ones.

 

[vapero]

ok, you already have a lot of info from us, now it's your turn, what are you building? a preview?

 

[C3RB3RU5]

Sorry for late reply started new job and waiting for finances to get to a point where I can send a design to a fab company to get made. When I finish the design on my CAD/CAM software i'll post the result. Unfortunately the laptop I had the software on took a crap and need to replace the motherboard before I can even start so it will be awhile yet.

I was more looking for advice for the near future, just so I knew where to start. I was a machinist for six years so I do know what I'm doing as far as the designing and could make it myself if I had the right machinery.

I will say that if either of you or anyone else, that posts showing interest in the final result, would like one for yourself I would get you one made for a fair price and send it to you. I'd give the two of you 10% off the cost I would ask everyone else to pay for the initial help you provided. Maybe the design won't be your cup of tea or you may not even like mech mods but if you do then they will eventually be a reality and available.

 

[sonicbomb]

Sounds like a deal. Let us know when your prototype is ready.

 

[C3RB3RU5]

Will do

 

[sonicbomb]

I just tested my new Stingray X clone using the 'hybrid style' top cap, and the voltage drop is six hundredths of a volt lower than the SMPL at a 0.33 ohm load. W00t.
But interesting though as it has a copper inner and and SS outer, rather than full copper. But it has a greater number of smaller tighter tolerance threads, I'm guessing that's where the efficiency increase is, I don't know. I would imagine the metal purity is also a factor.

 

[Mooch]

I just tested my new Stingray X clone using the 'hybrid style' top cap, and the voltage drop is six hundredths of a volt lower than the SMPL at a 0.33 ohm load. W00t.
But interesting though as it has a copper inner and and SS outer, rather than full copper. But it has a greater number of smaller tighter tolerance threads, I'm guessing that's where the efficiency increase is, I don't know. I would imagine the metal purity is also a factor.

If we assume 3.7V into that 0.33 ohm load, that's about 11.2A. The resistance change to cause a 0.06V drop difference at 11.2A is about 0.0054 ohms (5.4 milliohms). I think you're right, the copper would have some effect but it would be smaller than the effect from the greater contact surface area (from the more numerous threads).

 

[sonicbomb]

In addition, using the hybrid cap made almost no difference, 0.02 volts at the same resistive load. I did both tests with a fully charged VTC4 straight off the charger reading 4.2 volts

 

[Mooch]

Ahh...OK.
The VCT4 at full charge probably did not drop all the way to 3.7V when firing but that would mean the resistance change between the two setups was even lower.