thanks for all the replys looks like this place may be more helpful than i thought! anyways I received my lava tube today and i love it. i was reading something where someone said that using DCT's on the lava tube will regulate the voltage at 3.7 volts because of the regulator it has so is the same true even if the DCT is over 2-2.2 ohms?
[ ******* I didn't mean for this post to get so long - sorry! ******* ]
Here's all you will ever really need to know about volts, ohms (the electrical units that resistance is measured in), watts, and amps, as they relate to vaping.
Volts are the electrical equivalent of water pressure. They higher the volts, the more electrical "pressure" that tries to flow through a circuit, like the circuit from your PV battery + (positive) terminal, through the resistance wire of the coil (or coils), and back to the - (negative) terminal of the battery.
Ohms is the resistance of the coil to the flow of the electricity. Coils (atomizers) are rated in ohms, with ratings like 1.5, 1.7, 1.8, 2.0, 2.4, 2.8, 3.0, and sometimes higher. A water analogy of resistance might be a flow of water going from a big pipe into a small pipe, or sticking your thumb over the end of the hose.
The lower the resistance of the coil wire, the easier it is for electricity to flow through it, and the easier and faster the electrons that make up the electric current can bump into other electrons in the wire and heat them up via simple friction.
(This might seem counter-intuitive; I used to think that higher resistance would create more heat, but that's not the case).
As the electricity flows through the resistant wire that makes up a coil, the amount of heat generated - the heat that warms the e-liquid and vaporizes it so you can inhale it - is measured in watts. A typical range of watts that most people vape at is probably about 5-7 watts per coil (most devices use a single coil, but some cartomizers use two coils, and I'm not a big fan - they take twice as much power), although some people might like a little less wattage, and some people vape as high as 12 watts.
Lastly, there are amps to consider; amps are like the total flow of water through a pipe. We need to consider amps because all PV's have an amp limit; usually at least 2.5 amps, but sometimes 5 amps, and maybe even higher. I'm not sure if your Lavatube has a 2.5 or a 3.5 amp rating, but I have a feeling it's 3.5, so let's go with that.
There are two very simple equations you can easily learn that will let you figure out exactly what resistance of coil or coils you can use with any device, as long as you know its amp rating. If you try exceed the amp rating by trying to create too many watts by using too low a resistance of coil(s), the device will limit its output voltage so it doesn't exceed that amp rating.
They might seem intimidating, but they're really not. You can get the hang of them very easily if you just keep your brain from cramping up. Thinking about bunnies, puppies, and fluffy clouds first will help.
Here's the first one:
Volts times volts divided by resistance = watts. (V x V / R = W)
So with a single 2.0 ohm coil at 3.7 volts:
3.7v x 3.7v / 2.0 = 6.845 watts. Probably a pretty good vape.
Now here's the second one, used to figure out how many amps you're drawing. (How are the bunnies?)
Amps = watts divided by the volts used to create them. (W / V = A)
From the example above:
6.845 watts / 3.7 volts = 1.85 amps; well within the limit of just about any PV.
Now let's say you feel like cranking a 1.5 ohm coil (single or dual, the math stays the same - don't ask) at 5 volts.
Again, V x V / resistance = watts
5v x 5v / 1.5 ohms = 16.667 watts
And again, amps are equal to the watts created divided by the volts required to create them, so:
16.667 watts / 5 volts = 3.33 amps. Fine if your amp limit is 3.5, not fine if it's 2.5.
So the short answer to your question "is the same true even if the DCT is over 2-2.2 ohms?" is IMO "no, you'll be fine".
Once you get the hang of these two equations, you can figure out what resistance of coil to use with any device. And a good rule of thumb is to use the highest resistance coil that you can as long as you can still generate enough watts (heat) to get a good vape, because that will lower the amps, and therefore extend the run time of the battery. Makes sense, since they're rated in milliamp hours (mah).
A 1000-mah battery can put out 1000 milliamps (1 amp) for one hour. If you're drawing 2 amps, it'll last for 1/2 hour of continuous vaping, and if you're drawing 3 amps it'll last for 1/3 of an hour, or twenty minutes.
Try this example to see how you can extend the life of your Lavatube battery:
Say you want to power a single coil at 7 watts.
If you use a 2.0 ohm single coil, that would take 3.74 volts. 7 watts / 3.74 volts = 1.87 amps
If you use a 3.0 ohm single coil, that would take 4.58 volts. 7 watts / 4.58 volts = 1.52 amps. About 20% longer battery life.
Lastly: "DCT" is an odd name for a tank, since it seems to imply that you need to use a dual coil cartomizer in it, which you don't.
Unless you have a preference for dual coils, you'll get (almost) twice as much battery life by using a single coil instead. A 1.5 ohm dual coil carto is made from two 3.0 ohm coils wired in parallel so that their total resistance is 1.5 ohms. The important part is that you have to warm each one to just about the same temperature as the coil in a single coil, so you have to use a lot more power to do that. The total watts will be the same in the single coil carto and the dual coil carto, but in the dual coil, two coils will be sharing them.
I use single coil cartos only - at least when I used cartos - and most advanced atomizers use a single coil anyway. I now use the Vivi Nova tank/atomizer, and it's just about the most popular attachment right now IMO. It comes with three atomizer heads with wicks, in resistances of 1.8, 2.4, and 2.8 ohms. Your Lavatube could rock any of the three just fine, but again, you'll get the best battery life with the 2.8.
Confused? I know
I am.
Welcome, and good luck