Why are you measuring resistance in "voltage drop"?

[Dampmaskin]

When it comes to mech mods, the common practice seems to be using voltage drop at a certain voltage/current, in order to describe the mod's resistance.

Why not just use resistance and be done with it? That would take many unneccesary variables out of the description, and yield much more consistent, relevant, and accessible resuts.

Wazzupwidat?

 

[State O' Flux]

When it comes to mech mods, the common practice seems to be using voltage drop at a certain voltage/current, in order to describe the mod's resistance.

Why not just use resistance and be done with it? That would take many unneccesary variables out of the description, and yield much more consistent, relevant, and accessible resuts.

Wazzupwidat?

Hey D-skin...

I believe for most, it's a matter of measuring the functional performance of the mech/battery as a unit. Voltage drop, much like amperage draw, is a common test when measuring performance of a circuit, and a mech is nothing more than a way to close a circuit between battery and heating element.

One could measure the net resistance of a mech with a dummy battery in place, to make the connection from button to positive terminal, or one could measure the resistance of individual pieces parts... either to extrapolate a potential performance of the mech mod itself - but a VD test covers all the bases and gives you a real world and quite relevant performance value by which to compare.

Now, saying that, there is a point of ridiculousness where even the most experienced vapist can't tell the difference between a 0.00 VD and a 0.04 VD. When we get that low, it's more of an abstract than a justifiable rational for selecting a mech mod.

It seems that only jkuro at Calivapers has really made it his life's mission to test as many mechs as possible, using accurate and repeatable instrument and load testing. When others do VD testing, unless they duplicate jkuro's equipment and methods... I take it all with a very large grain of salt. ;-)

 

[Dampmaskin]

Thanks for your reply.

The issue I have with it is this: When published, these numbers are meant to describe only the mod, not the battery/mod/atty setup. I can see the use of voltage drop for describing a part of a whole system while in "real world" use, but that is not what's being described.

It's like using "turn X degrees left", "set Y speed" and "move for Z units of time" to describe a location on the planet, instead of just using the coordinates.

If you don't know the starting points, the relative directions will get you nowhere. Admittedly, if you do know the starting point, you can work it out, provided that you have a stopwatch, a speedometer and a protractor. But it would still be more accurate, not to mention easier, to just use the coordinates in the first place.

From the page you linked to:

The testing is to isolate the mod itself and to get actual voltage drop and current flow and not be influenced by atomizer and battery resistance.

If one wants to take the battery out of the equation, fine, take the battery out of the equation. But then proceeding to not really take the battery out of the equation (or maybe take it it out, and then stick a virtual battery in there instead), just seems backwards compared to using the "true" (as in the simplest fully accurate) measure of performance. Which cannot plausibly be anything other than resistance.

To recap, I cannot see that he is in reality measuring anything other than resistance. He then presents the result as a bunch of values (current, voltage, current loss, voltage drop).

The resistance can easily be calculated from these values, provided that one knows exactly what he means by each number. So why opaquely present the result as four interconnected values, when it can more easily and more accessibly be presented as a single number?

Maybe using a single number is just too simple, transparent and unglamorous, and would take too much voodoo out of it?

 

[State O' Flux]

Well I think I see your point, but it's not clear to me. The issue I have with it is this: When published, these numbers are meant to describe only the mod, right? Not the battery/mod/atty setup? Well, the battery and resistance are part of the equation, but always identified as a separate, hopefully repeatable and comparable value. Is it perfect methodology? No. Does it have enough consistency for repeatable, performance comparison purposes? Yes.

I can see the use of voltage drop for describing a part of a whole system while in "real world" use, but that is not what's being described, is it? Yes, that is what's being described - and the practical reason for using standardized control elements, in a closed, "hot" circuit. We are measuring the power loss due to resistance, that resistance causing energy to be lost in the form of heat through the mech body surfaces.


It's like using "turn X degrees left", "turn Y degrees right" and "go Z distance" to describe a location on the planet, instead of just using the coordinates. I wouldn't see it that way, but then we don't have to see everything the same way. ;-)


If one wants to take the battery out of the equation, fine, take the battery out of the equation. But jumping through hoops in order to compensate for the fact that one did not really take the battery out of the equation (or maybe one took it out, and then stuck a virtual battery in there instead), just seems backwards compared to using the "true" (as in the simplest fully accurate) measure of performance. Which cannot plausibly be anything other than resistance.

Maybe a single number is just too simple and unglamorous?

Never knew electrical tests were considered glamorous. If that's true, then 20 years ago, I was a damn stylish feller.

A simple resistance test doesn't test actual, loaded performance, and only when a load is applied, does this resistance become apparent.
I can measure a mech from one end to the other and get 0.00Ω resistance, but until you apply a load and energize the unit as a whole, you won't be able to tell if that low resistance translates to energy transfer efficiency, or energy loss as heat transfer in the mech body.

It's no big deal if you prefer to see it from a differing perspective. In real terms, when we get down to 0.10 and below, the test starts to become a bit academic. Now, if the test demonstrates a voltage drop in the extreme... suggesting that under load, a particular device is not transferring the full energy of the battery to the atomizer, wasting perhaps as much as 25% of your available energy to heat... that's where the value becomes readily apparent.

Once you've handled a "hot" mech, you have a better idea of what I mean by energy loss to heat.

 

[Dampmaskin]

Ok, maybe I'm over-simplifying things. On one hand, resistance ought to be linear, and a mech mod is an extremely simple circuit, so in theory it should be possible to describe it with an extremely simple and idealized model.

On the other hand, I have no first hand experience with them, so I'm probably talking out of my posterior. I am going to get my first mech, a nemmy clone, soon (I hope, it's from Slowtech), so perhaps after vaping on that for a while, I will grok the subtleties.

 

[State O' Flux]

Ok, maybe I'm over-simplifying things. On one hand, resistance ought to be linear, and a mech mod is an extremely simple circuit, so in theory it should be possible to describe it with an extremely simple and idealized model.

On the other hand, I have no first hand experience with them, so I'm probably talking out of my posterior. I am going to get my first mech, a nemmy clone, soon (I hope, it's from Slowtech), so perhaps after vaping on that for a while, I will grok the subtleties.

Went and took a nap... meds make me sleepy sometimes.

I get where you're at now, my friend. I see, with no mech experience, how you'd think it was linear... that there would be an exact correlation of resistance to power loss, so why bother with a performance test - yes? In theory, you should be perfectly logical in thinking that.

And that's where it falls apart, because maybe there is, and often in the real world, there isn't a linearity... and the only way to be sure, is with an applied load test.

When you look at jkuro's tests you might think... how could nothing more than some simple metal tubes, buttons and contacts - with a relatively massive cross-sectional area that should easily handle upwards of 50 plus amps without a blink of an eye - have anything but a 0.00v energy loss, or greater than 0.00Ω resistance?
Yet low and behold, there are mechs with notable energy loss and if one were to look, probable included resistance too. Granted, for most it's academic, but a few genuinely do stand out.

Has VD testing been taken too far as a make or break determination for a purchase? Perhaps so, especially if one splits hairs and buys a 0.01v mech over a 0.07v mech... because they think that the 0.06v actually matters.

 

[inter_ceptor00]

I may be wrong, so correct me if I am, but I think the issue with VD is that it affects the voltage of the mod before it hits the atty, which would cause a loss in total wattage since the atty "resistance" would remain constant but the usable voltage would be lower due to a higher VD. So it's really a case that there are 2 unique resistances at least when thinking about a mech mod.

 

[asdaq]

You can take resistance readings between a variety of points in a mod and pinpoint what segments of the circuit are adding the most resistance, but for vaping it is good to know the sum of these parts, so VD is the "gestalt" measurement.