TCR wire in VW mode

[WickedWicks]

TCR wire (let's say SS) is said to give a good experience on a Mech as the vape starts with a boost and with the resistance rising the wattage drops accordingly.

Does the average regulated mod behave the same in VW mode, or does it monitor resistance while firing and adjusts on-the-fly to keep the set wattage?

 

[93gc40]

Stainless wire would probably be no issue for VW, resistance wise... But Nickle and Ti will not be safe to use in VW or VV due to off gassing. also due to the ultra low resistance of the wire. I have my doubts about SS where Gassing is concerned.

Mech mods have NO boost. Voltage is what the battery is putting out at any given time. Now if the resistance of the wire changes, the wattage will also change. wattage will also change as the charge of the battery reduces.
Most VW devices adjust wattage based on resistance and Buck/Boost battery voltage to maintain set wattage output.

 

[WileE]

TCR wire (let's say SS) is said to give a good experience on a Mech as the vape starts with a boost and with the resistance rising the wattage drops accordingly.

This is both an attempt to answer the question and a test since it'll be the first video I've put on ecf.

@WickedWicks - The second part of your premise is correct as it applies to TCR wire on a mech mod, however the first part as to it being enjoyable is entirely dependent on several factors as follows:

• The TCR wire is safe to run on an unregulated mod? Nickel is a Hell NO, as for the rest it's subjective do your research! I have strong OPINIONS & CONCERNS but that's for another thread!
  
• The wire has to have enough TCR to even make a noticeable difference.

Ex.

1. SS 316L .25Ω Crown coil TCR = .00092 div by 1.8 = .000511 TFR rise per °F rise in temp, so 68°f start + 400°f rise = 468°f final temp means 400 x .000511 = .204 TFR @ 468°f So .25 x 1.204 = .301Ω @ 468°f Next plug it into ohms law and the .25Ω coil on a tube mech @ 4.1v = 67w when you hit fire and when it reaches 468°f the coil res will be .301Ω & drawing 56w Total change is 11w over 400° might be noticeable, but not very!
2. NiFe 52 .25Ω coil TCR = .004 div by 1.8 = .00222 TFR per °f rise & per above 400 x .00222 = .889 TFR @ 468°f So .25 x 1.889 = .47Ω @ 468°f Plugged into ohms law we get the same 67w when we hit fire on a cold coil, but now at 468°we're only drawing 36w for a total change of 31w Almost halved & Yep that will definitely be noticeable, but not necessarily in a good way depending on the next point.

• Using ex #2 due to bullet #1 you must design your (TCR wire mech build) for the desired hot temp!! What that means is if you've got your Kanthal RDA dialed in for a .25Ω build on your trusty pipe bomb then the NiFe 52 coil would need to be roughly .25 Hot Ω (if the surface area of the NiFe coil is comparable to the kanthal) So using ex above .25 div by 1.889 = .13Ω cold target resistance. Note that is just a starting point.

As mentioned the kanthal RDA build was dialed in/optimized for 4.1v @ .25Ω meaning correct gauge, diameter, and # of wraps.
I.E. you couldn't run a .25Ω dual kanthal 28ga 2mm 2.5 wrap coils set in a tube mech at 67w unless you're building it for Ghost Rider

An optimized .25Ω dual kanthal coil would be 24ga 2.5mm 6/5 wrap with a surface area of .326 sq in, heat flux of 190868 @ 67w, and a heat capacity of 94.4 mj/K (lower heat capacity = quicker ramp time).

An NiFe 52 build optimized for hot .25Ωish on a mech would be cold res of .16Ω dual coil 26ga x 2.5mm di x 9/8 wraps with a surface area of .36 sq in, heat Flux of 276639 @ 105w (when cold) changing to .302Ω with heat flux of 147541 @ 56w when hot 468°F The heat capacity for this build is 91.46 mj/K​

Assuming the items above have been addressed it's not just enjoyable it's Kick A_S and the advantages are 4 fold using examples above.

1. more surface area on the TCR wire. .36 vs .326 = 9.5% increase in surface area
   
2. Ramp up time is way faster on the TCR wire even though it has more surface area. Heat Capacity of 91.46 vs 94.4 = 3.1% improvement in ramp time if using same watt, but it's not
   
3. lower initial "cold" ohm results in very fast ramp up times (pre-heat boost) for TCR wire on mech 105w @ .16Ω - 56w @ .3Ω vs 67w static for kanthal at .25Ω = 57% pre-heat power boost for the TCR wire
   
4. It self regulates cutting power as it heats, thus allowing a long pull without getting a burned hit.

Does the average regulated mod behave the same in VW mode, or does it monitor resistance while firing and adjusts on-the-fly to keep the set wattage?

The average Chinese regulated mod is VW & most check cold resistance then calculate required voltage to achieve set wattage. The result is that wattage set is only applied when cold, voltage is fixed an anemic vape may result from slow ramp up & half desired watts when hot.
The video below if it works shows a NiFe 52 on a DNA - 40 in watt mode set to 40 watts. It proves that the DNA-40 (and I'm told all evolv boards) monitor resistance in watt mode and adjust on the fly to maintain set wattage.

View media item 429258

 

[WickedWicks]

Thanks a lot WileE for the illustrated examples. That pretty much highlights all aspects

The average Chinese regulated mod is VW & most check cold resistance then calculate required voltage to achieve set wattage. The result is that wattage set is only applied when cold, voltage is fixed an anemic vape may result from slow ramp up & half desired watts when hot.

But if they maintain voltage the result should be very similar than on a mech, no?

 

[WileE]

Correct with voltage locked on a cheap VW device the result is similar to a mech accept you don't know where is it locked, all you know is where you set the watts

At least on a mech you know where the voltage is, say 4.1v for fully charged batt with slight sag upon fire.
On the other hand a cheap static VW device voltage is entirely dependent on what you set wattage to?
Set Watts to low and all the benefits listed in previous post become detriments. To high and you get burned hits.

To summarize the differences:

1. TCR wire on a mech requires you to build the coil/s for desired hot resistance. This doesn't require a graduate degree in physics since most vapors will have already optimized or at least have a decent working Kanthal build ironed out for their mech. whatever the res of that build, it's your hot target for the TCR wire
   
2. TCR wire on a cheap static VW device requires you to set device wattage for optimal pre-heat power setting required for the given TCR build. This requires so much information to be considered to get it right most people won't. Anyone smart enough to do it would just get rid of the cheap mod and buy themselves a quality TC/VW mod.
   
3. TCR wire on a high quality Dynamic VW chipset (Evolv DNA - 40/200) will vape just like Kanthal in watt mode. Device compensates real time for TFR changes maintaining desired set wattage. This is exactly what the video I posted shows. In Watt mode the TCR wire had a perfectly flat power delivery just like kanthal due to the impressive real time resistance sampling & voltage compensation

 

[spalife]

 

[GeorgeS]

Well er sort of.

• As long as your coils cold resistance is a safe value for your battery in use, TCR wire is as usable with a mech mod as any other wire. The power delivered will go down as the wire heats up (self regulating).

• The same can be said on a regulated VV mod. For any given voltage setting the wire will only get 'so hot' (self regulating).

• The VW mod represents a different profile with Voltage*Current=Wattage. As the wire heats up any self respecting (and sampling) VW mod will detect less current and therefore increase the voltage to compensate. Repeat endlessly and ether the voltage limit of the mod will be reached or the thermal run-a-way has destroyed the wick and/or coil.

I use Ti and SS builds on my old regulated VV mods all the time. The trick here is that these old puppies won't fire anything less than 1.0-1.2 ohms so very thin wire and/or lots of windings.