How dangerous is stacking for 6v? prove it.

[mwa102464]

It's all good Markfm,


since where discussing VW & VV , here is something, with my Darwin I can adjust the Watts .1 or .2 to fine tune, but with VV you really cant do this can you ? the tuning of VV is .1v where Darwin you can adjust .1W So I can stay at 4.1V and adjust my Watts from 9.8w up to 10.3W and still b at 4.1V,,,, with a VV unit this cant be done correct, it adjust the voltage by .1V not the watts by .1w like the Darwin controller does,,, therefore I would have to think it should be called a VW unit, not a VV

 

[Canuck]

All this talk of VV devices has me wondering if I should just order a Provari so that I can do my own comparision of VW versus VV, so many different things to try when your this new to vaping, lol

 

[kingcobra]

Couple of comments after reading through this rather long thread

There is risk in pretty much everything. Our day is full of applications of risk management. Every time we eat or drink something there is a risk of dying, for instance. Every tiime we cross the street, get into a car, etc, we could die.

Now the goal is to manage this risk, for instance we want to look both ways before we cross the street. Sometimes even the most prudence cannot manage the risk enough to render it acceptable. For instance crossing a race track with cars whizzing by at 200 mph generally wouldn't be considered worth the risk.

However, this brings us to the element of reward, as in the risk/reward ratio. If someone had a gun to your head, then you would cross the race track of course. If someone paid you enough money to do it and you knew the risk, say an 80% chance of success and a 20% chance of dying, but you got a million dollars for doing it, and the money was that important to you....

As for the issue at hand, we need to ask ourselves if the benefits of using riskier setups such as double stacked batteries are worth the risk. The answer here is that it is hard to imagine this being the case, given that there are alternatives which produce the same results without this added risk.

So therefore we could even probably say that it is irrational to use such a setup. Not everyone is rational enough to accept arguments of rationality though

On another note, there is a huge market for VW devices and this market is being underserved, to say the least. Companies need to get with it here.

I can't believe the prices at that Russian site. Several hundred bucks for an end cap? Looks like you could spend several grand on a PV there. That is absurd.

 

[sailorman]

.....
I can't believe the prices at that Russian site. Several hundred bucks for an end cap? Looks like you could spend several grand on a PV there. That is absurd.

I'm not sure that's the case. I think you're misinterpreting the price lists. It's very difficult to decipher that site. I'm pretty sure the unit with carrier, controller and a rebuildable atomizer tank runs just under $300. They have pre-configured kits priced like that. Some of the RBAs they sell are popular in Germany. I think the one they call the katy(?), or something like that, has big following. Some of the European members here have that one. The prices are a bit high for us poor Americans, but not terribly out of line for other places in the developed world.

 

[sailorman]

Rocket, with a VV the unit continues to run fine, but half the total power now being used, same as on a single cell fixed voltage. The user would adjust the voltage upward if they want to increase output power, though you will likely run into the regulator max voltage limit.

4.5v, 1.5 ohm is 13.5w. Switching to 3 ohms would require 6.36v for the same output power. Neither notcigs Pro nor provape Provari go to that high a voltage.

Not exactly. While 4.5V is 13.5W with 1.5ohms, those 13.5 watts are being split between the 2 coils. So, each coil is consuming 6.75 watts. If you pop one coil, you will suddenly begin supplying one 3ohm coil with that 4.5V and it will be consuming 13.5 watts all by itself. You most certainly would not want to adjust the voltage upward. You'd want to decrease it, if anything.

A 1.5ohm dual coil and a 3ohm single coil have exactly the same power.

 

[sailorman]

All this talk of VV devices has me wondering if I should just order a Provari so that I can do my own comparision of VW versus VV, so many different things to try when your this new to vaping, lol

Don't buy a Provari just to test that. If consistency of vape is what you want, a VV can't do the job unless it has an infinite resolution and you have constant feedback as to both the resistance of the coil as it changes with heat and use, and the battery condition. You'd have to take all that into account, instantaneously do the calculations, and almost constantly adjust the voltage to ensure that the coil was operating at a steady wattage.

This is why VW is better. It's like having a well functioning cruise control in your car as opposed to trying to control your speed by dragging the brakes and changing gears.

 

[markfm]

That is incorrect if talking vv, which acts as a constant voltage source at whatever voltage you have set it to. If you lose one coil, the second one doesn't double up on power, it will continue to operate at 6.75w unless you change the voltage.

The circuit is two resistors in parallel. Each coil has a 4.5v drop across it, 1.5a of current, 6.75w power. If you blow out one coil, open circuit, the remaining 3 ohm coil still has a 4.5v drop across it, 1.5a current, 6.75w. You would have to increase voltage as per my prior post if you still want to dissipate 13.5w.

(Whether the 13.5w off a single 3 ohm is the same vape-wise as 13.5w off a dual coil is a different discussion. That single remaining 3 ohm has half the contact area with the liquid of both coils, and is being run hotter, a more concentrated heat source.)

Easy to mix up, just that I was responding to the vv part of Rocket's question. In a vw, blow a coil and the device should try to crank voltage up by itself, to sustain the power set point.

 

[sailorman]

Right. Brain fart. The single coil would continue to operate at 6.75 watts. The whole concept of having 13.5w is misleading though. 13.5w is an entirely different animal in one coil as it is when split between 2 coils. You'd never want to increase, the voltage to dissipate 13.5w, or anything near that, to compensate for the loss of a coil.

Other than for purposes of calculating current draw, the 1.5ohm rating of a dual coil carto is meaningless. It certainly doesn't imply any vapor characteristic that you'd get at 13.5 watts.

 

[markfm]

Agreed

Equal power doesn't really always get an equal result.

 

[Canuck]

Well maybe I'll hold off ordering the provari until I hav a chance to try out my firends lavatube, since they should be close in performance. It will give me a chance to compare my kicked silver bullet to a vv device without spending more than $250, besides I already have a DIY 5V box mod on order from madvapes too.

 

[Rocketman]

Back to my blown dual coil
If we took three cartos, a 3.0 ohm single coil,
a 1.5 ohm dual coil with the top coil blown,
and a 1.5 ohm dual coil with the bottom coil blown,
and vaped them at something reasonable like 5.0 volts/8.3 watts,
which one would produce more vapor? Which one would taste cooler/hotter?


Or, how about a single coil 1.5 ohm on a lower voltage like 3.7 volts/9.1 watts,
compared to a 1.5 ohm dual coil at 3.7 volts,
compared to a pair of 3 ohm cartos on a twice pipes mod at 3.7 volts?


Does coil temperature and surface area come into play here?
or is it just a game of watts?

 

[sailorman]

In you dual coil example, my guess is that the one with the good coil located closer to the mouth would feel warmest.
They'd all be producing the same amount of vapor, assuming the filler was equally saturated.
The coil surface areas and temperatures would all be the same.

With the single coils vs dual coil, the 1.5ohm 9.1 watt would produce less vapor than a 1.5ohm dual at 3.7 volts, but the dual would be a tepid fog compared to the single coil, which would be a nice warm vape.
The pair of 3ohms on a twice pipes mod would likely produce more vapor than the dual coil at a slightly lower temperature.
There is a pre-heating effect of the lower coil that increases the vapor temperature of a dual coil to some extent, but not enough to overcome the handicap of using a lame 4.56 watts.

 

[Rocketman]

So, separating the 3 ohm coils reduces the vapor temperature (tepid) over say, a bifilar wound 1.5 ohm coil made with a pair of 3 ohm wires into a single coil (about the same as a single wire wound into a 1.5 ohm coil)?
The additional exposed surface of the dual coil at 3.7 volts doesn't heat enough vapor to produce a nice warm vape?

 

[sailorman]

I don't know what bifilar wound means. I'm assuming you mean a coil consisting of parallel strands, wired in parallel? I don't know if the temperature would be appreciably different than a dual coil in that case. All I know is that that the theory is that the lower coil in a DC preheats the juice and/or vapor before it reaches the upper coil. That is supposed to result in a warmer vape than the 4.6 watts would imply. So, it would be warmer, to some unknown (to me) degree, than just vaping two PVs with 3ohm cartos at the same time.

The additional exposed surface of the dual coil at 3.7V, heats enough vapor, just not warm enough to produce a nice warm vape, IMO. Obviously others will differ. It's not as warm as the single 1.5ohm coil. That's pretty undeniable. A lot of people are happy with the sub 5 watt vapor of a lot of little mini-cigs, so if the effect of a dual coul is to produce that level of warmth, but more vapor, then a lot of people would be happy with it.

 

[WCSR]

Look up watt monitor. I don't want it to be a matter of semantics either.

Most of the chips in the telecommunication market use an external shunt to measure current, measure voltage with a built in AtoD converter, calculate watts and vary an output frequency based on Ohm's Law and a power to frequency conversion factor. But, still ohm's law. The frequency is then used to control the voltage output of a high frequency DC to DC converter with the output filtered DC. Output level is set via a potentiometer and comparator in the DC to DC converter. Even though voltage and current monitoring is used, the output is controlled by calculated power as set by a little potentiometer. Compensates for resistive and reactive loads (RF power circuit).

Does not defy ohm's law.

Pulse-width modulation

 

[WCSR]

It's some pretty impressive stuff. Problem is, I think you have to go to Russia, or at least Europe, to get it. The videos are really pretty cool, even though they're in Russian. Best as I can tell, a full set with a full blown set of tanks and attys runs about $280, which is pretty reasonable considering the price of a bare Provari and a good rebuildable atty.

$260-$300 was what I was figuring too. Depending if you wanted a transparent body or not. Can't say I'm amazed at how high tech this is really getting, because everything is high tech these days. I'm just ecstatic that the vaping experience is getting the technology to make it as consistent as smoking was. All 20 cigarettes in a pack burned the same, and tasted the same. Hopefully we will get to the point where every ml in a bottle will vape and taste the same.

 

[Rocketman]

Generally, PWM refers to a lower frequency variable duty cycle DC voltage. Like the eGo at less than 100hz.
When the frequency of the pulse train goes higher, like 200000 Hz and is filtered into a smooth DC voltage you can't tell it from a straight DC voltage. MOST DC to DC converters, Buck or Boost work with high frequency filtered pulses.

The Darwin, The Provari, most Variable Voltage or Variable Wattage PVs (other than linear regulated) use filtered pulses. Some converters use variable length pulses some use pulse skipping.


and a bifilar wound heater would be like the difference in using stranded wire instead of solid.
4.6 watts is what you get when one coil of a DC pops open. That's lame

 

[BiffRocko]

It's like having a well functioning cruise control in your car as opposed to trying to control your speed by dragging the brakes and changing gears.

Awesome analogy. I couldn't have said it better myself.

 

[Rocketman]

You drive like that?
Actually a better analogy would be setting your engine for torque or horsepower as compared to RPM.

But we typically rely on the speedometer when driving and adjust with the gas pedal (even the cruise control does that).

Just funnin guys

 

[WCSR]

You drive like that?
Actually a better analogy would be setting your engine for torque or horsepower as compared to RPM.

Actually, you set an engine up for either torque or RPM. Both are relative to the mathematical figure that is horsepower. But I get what you're saying... I actually started to make the analogy earlier, myself...but deleted it out of my post. Torque would be relative to amps, RPM would be relative to volts, and horsepower would be relative to watts. Not a strange analogy to make being that 746 watts is equivalent to 1 horsepower.