Digger, I appreciate the thoughtful and extremely civil post.
Yes, this can be an overwhelming subject, so I'd like to re-state the exact same advice in a simpler form.
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All PV's work essentially the same way. A battery sends current to a coil or coils, which in turn warm and vaporize the juice to create vapor. The coils get warm because of an electrical term known as "resistance"; in other words, how hard does the coil "resist" the flow of electricity through them, causing electrons to bump into other electrons, creating friction and thereby heat, very much like the way a microwave oven heats things up. All a microwave does it get the atoms in water molecules to move faster, bump into each other, and create heat through simple friction, like the way you can get your arm warm by rubbing it with your hand.
The coils are contained either in a stand-alone atomizer (often used for "dripping", wherein the user "drips" juice right onto them and then vapes through a mouthpiece/drip tip), a "cartomizer" (combination atomizer and cartridge, where the juice is held in a polyfill that is in close proximity to the coils of the atomizer, which gives a better vape than a separate atomizer and cartridge, because the juice is delivered to the coils better; and the coil (singular) can also be found at the top of some specialized tanks that use wicks alone, and no polyfill, to feed the juice directly to a coil at the top of the tank.
I think it's safe to say that most people use cartomizers in one way or another. One very common use of a cartomizer is inside a tank, typically between 3.5 to 6ml in size, with the cartomizer running longitudinally through the middle of the tank, with o-rings sealing the juice inside the tank. A hole, holes, or a slot is either pre-made or added by the user to allow the juice to enter the cartomizer at an optimal rate. The idea, with or without a surrounding tank, is to keep the polyfill moist, but not so soggy that juice leaks out of it. Think of it they way you would with the soil of a houseplant; certainly never dry (polyfill will get scorched when too dry), and not too wet; just constantly moist. If a cartomizer is used without a tank, it must be constantly added to, maybe every ten hits or so, to keep it moist. A cartomizer inside a tank does not need to be tended to at all, until it becomes clogged after a few hundred, or maybe even a thousand hits, at which time the easiest thing to do is put another one in. Many people do clean them with good success.
One huge key to a good vape is to have the coils at just the right temperature to provide good vapor and release all of the flavor of the juice, and that obviously means delivering just the right amount of voltage from the battery to do that. I think it's pretty accurate to say that for most people and most juices, the "ideal" amount of heat/current that needs to be delivered to each coil is between 6 to 8 watts. Some like it higher, some like it lower, and it can even depend on your mood. Some day you might like your bagel on the light side, and some days you might feel like having it a little more dark and crunchy.
This is exactly where variable voltage comes in.
This is the only formula I will trouble anyone with, but it's a very important one, and is really pretty easy:
The number of watts per coil is equal to the volts going to it squared, divided by the resistance, measured in ohms, of the coil or coils in the atomizer. The formula then is "Volts x volts / resistance = watts" This is Ohm's Law.
From this formula, it can be seen that with a fixed voltage PV, it is only possible to vary the wattage by using different resistance coils/atomizers. Achieving the "exact right" wattage is difficult, but certainly not impossible. But then again, the "exact right" wattage will vary by flavor of juice, and as I previously noted, perhaps even by your present mood.
With a variable voltage PV, you can dial in any amount of watts per coil you want to, regardless of the resistance of the coil or coils, limited only by the amp capacity of the device. (OK, I have misinformed you; one last formula is in order);
Amps; consider a household lightbulb that is 110 watts, running on 110 volt household current. Amps are equal to watts divided by volts, so that would be 1 amp. A fifteen amp circuit, protected by a 15 amp circuit breaker, could run fifteen such light bulbs.
Ok, so consider a variable voltage PV that can handle 3.5 amps, like the ProVari V2. Its "circuit breaker" will trip at anything over that. Let's say it's set at 5 volts, and is powering an single coil atomizer/cartomizer that has a resistance of 1.5 ohms.
V x V / resistance = watts. 5 x 5 / 1.5 = 16.66 watts.
At 5 volts, that is 3.33 amps (Amps = watts divided by volts; 16.66 / 5 = 3.33). Just under the limit of the circuit; great.
So there it is; the reason, as best I can explain it, that variable voltage is the only way to achieve the best-tasting, most productive vape you can get on a wide variety of "attachments" (atomizers, cartomizers, clearomizers, Mega Dual Coil Cartomizers, Giantomizers, CE2 tanks, Stardust/eGo vision tanks, or whatever else). Remember that you can use almost any type of attachment on any battery/PV/power unit that uses the same type of thread pattern, with the "510" thread pattern being by far the most common one. Smaller, ciggie-like devices usuallu use the "808" thread pattern, although adapters can be had. That said, the very small battery of a device like the Volt will not be able to power most of them.
You can get a very good vape on constant voltage devices, but you will be limited to lower resistance atomizers, especially at the 3.4 to 3.7 volts that most constant voltage devices put out. And dual coil attachments will be almost unusable, since a 1.5 ohm dual coil atomizer/cartomizer, for example, will require that "optimal" 6 to 8 watts for each of the two coils, bringing the wattage required for the entire device to more like 12 to 16.
At 3.7 volts, a dual coil 1.5 ohm atty/carto will get 3.7 x 3.7 / 1.5 = 9.12 watts, but only half of that - 4.56 watts - per coil. That is simply not, IMO, enough wattage per coil for an optimal vape. I just did it, so I am convinced for myself that it's too low; minimal vapor production, and the flavor is lacking. (Not enough electrical action going on to convince enough flavor molecules to release their bond to a water or juice molecule and get released into the vapor so that it can serendipitously bounce off of a particular taste bud belonging to yours truly). I would respectfully suggest that those who say it's "just fine" simply don't realize how much finer it would be at a higher wattage per coil, and that is not an offense punishable by death. None of us know what something is like until we experience it for ourselves.
With VV, you can adjust the wattage to wherever you want, simply by selecting the voltage you want using a button or buttons and an LED readout on the device. I just vaped my Backwoods Brew "Virginia" (tobacco) blend at 4.5 volts (on the same 1.5 ohm dual coil carto inside a Smoktech 3.5ml DCT tank), and that gave me 4.5 x 4.5 / 1.5 = 13.5 total watts, 6.75 watts per coil. Much better vapor production, better flavor. I just tried it again at 5.5 volts = 20 watts total, 10 watts per coil, and that's a bit much I think, although I might grow to like it. At any rate, I have the ability to adjust the voltage/wattage to find just the right amount of coil temperature to arrive at just the right vape I want regardless of the flavor of the juice, the kind of throat hit I want, what attachment I happen to be using, or as I say, the mood I'm in.
And so can anyone reading this.
Again, my recommendation for those who don't care what size your PV is, or whether or not it looks much like a stinkie:
Smoktech VMax, $128.95, free shipping
Four IMR 18650 batteries $30
Trustfire TR-001 charger $10.99
Smoktech 3.5ml DCT tank $11.99
Boge 3.0 XL single coil cartomizer $1.80 (Five for $8.95)
Smoktech VMax:
All About Vapor
Batteries and charger:
AW IMR 18350 700mAh LiMN Rechargeable Lithium Battery
Smoktech DCT 3.5ml chrome tank (on sale):
Dual Coil Cartomizer Tank or:
3.5ml Dual Coil Tank Chrome/Black
Boge XL 3.0 ohm stainless steel cartomizers:
XL Boge 510 Cartomizers 3.0 ohm
Again, if anyone buys any of this on my recommendation and does not like its performance, I will buy it from you for what you paid for it. Shipping will be on you, and I can pay you with PayPal before you ship it. Such a deal.
Vape on.
