Variable Volts-Watts and Ohms Question

[DavidOck]

Right you are, twg, but consider what you've just said. Terminals for current and voltage. So the watt-hour meter calculates watts. It doesn't measure them.

And it's a watt-hour meter, to track usage. to track consumption, so they can bill you for it. And circuit breakers / fuses will trip / blow at a level of over current regardless of the voltage. (Of course, the CB/fuse must be rated higher than the applied voltage...)

Don't know of any way to check Ω in a live circuit, most ohm meters apply a fixed, calibrated voltage across the load. No reason the electronics can't do that, of course,

 

[twgbonehead]

Right you are, twg, but consider what you've just said. Terminals for current and voltage. So the watt-hour meter calculates watts. It doesn't measure them.

And it's a watt-hour meter, to track usage. to track consumption, so they can bill you for it. And circuit breakers / fuses will trip / blow at a level of over current regardless of the voltage. (Of course, the CB/fuse must be rated higher than the applied voltage...)

Don't know of any way to check Ω in a live circuit, most ohm meters apply a fixed, calibrated voltage across the load. No reason the electronics can't do that, of course,

If that's your definition of "measure", then you can't measure resistance directly, either. An ohm-meter (the original, analog type) doesn't actually display ohms, it displays current. As a matter of fact, these meters can't even measure voltage directly, but have to "calculate" it from a current flow. As a matter of fact, these meters can't even measure current, all they can do is displace a needle by a certain amount, you then had to "calculate" the current by looking at what number the needle pointed to.

Damn, multimeters that can't measure ohms, volts, or amps? Wonder why they were so popular?

And yes, the meter on the side of your house is an energy meter (watt-hours) but in order to measure the energy it must continuously measure the power (watts) and integrate it. In the old-style meters, the "integrator" was just a bunch of gears that turned a set of dials. However, these meters DID measure power, and you could tell the amount of power being used by looking at how fast the rotary part was spinning.

 

[faulkan]

Just my two cents but wattage is a mystery to a lot of folks that are new to vaping not for the calculations but for what its actual role in setting up a device is. Variable voltage allows us to change the amount of voltage sent to a coil of a given resistance measured in ohms. The resistance among all the different coils varies quite a bit so with a variable voltage device, you would have to manually adjust your voltage if you change to a coil of a different resistance to keep it in your "sweet spot" which is your preferred setting with that particular coil. Let's say for instance that you are using a 1.8 ohm coil set at 3.6 volts. That's roughly 7 watts. That would make 7 watts your "sweet spot" in this case. Eventually your coil will need to be replaced and the only one you have laying around is 2.4 ohms. To achieve your 7 watt "sweet spot" you would have to use an Ohm's Law calculator to figure out you need to adjust your voltage up to 4.1 volts. Basically, watts is the amount of heat your coil is generating. In a variable wattage/power device, you set the device to your desired "sweet spot", 7 watts in this example, and it will do the math for you to keep the voltage where it needs to be to provide the same amount of heat.

 

[SoberSnyper]

I understand this, but the device can certainly calculate watts and be able to calculate if the set voltage with the installed coil resistance would result in more than 11 watts. I believe the device calculates the wattage and if the calculation exceeds 11 watts, it will only provide the voltage that would result in an 11 watt output.

All of these devices are microprocessor controlled and being microprocessor controlled, they can calculate.

Even though watts are not a "tangible" thing, in the case of explanation, it's easier to discuss it as if were tangible.

In reality, the limitations we are discussing here is based on calculations of what the projected wattage at the coil would be based on the measured resistance of the coil and currently set voltage output of the battery.

The point is that there are only 2 things that can limited in an APV, current(amps) or voltage(volts), watts cannot be limited because it can not be measured. A VW device takes the power setting you put in to calculate the voltage needed, it will then deliver the required voltage unless you exceed either the voltage or amperage that the device can deliver.

 

[SoberSnyper]

Strictly speaking, that is just not true. I gave my brother an antique watt-meter (no digital electronics in it, all passive components) that is a very accurate watt-meter. It has 4 terminals, the current goes through 2 of them, the voltage goes across the other 2.

The Watt-hour meters that the power company puts on your house USED to be strictly electro-mechanical devices. The amount of current changed the strength of the excitation field of a motor, while the voltage changed the driving EMF of the motor. The disk turned faster when more power was used (and these were designed and trimmed so that they provided accurate power measurements at different voltages and/or currents). Nowadays most of them are digital, because it's cheaper.

Please provide a link for either an analog or digital multimeter that has a power(watts) setting because I have never seen one. (Or heard of one.)

 

[SoberSnyper]

Strictly speaking, that is just not true. I gave my brother an antique watt-meter (no digital electronics in it, all passive components) that is a very accurate watt-meter. It has 4 terminals, the current goes through 2 of them, the voltage goes across the other 2.

The Watt-hour meters that the power company puts on your house USED to be strictly electro-mechanical devices. The amount of current changed the strength of the excitation field of a motor, while the voltage changed the driving EMF of the motor. The disk turned faster when more power was used (and these were designed and trimmed so that they provided accurate power measurements at different voltages and/or currents). Nowadays most of them are digital, because it's cheaper.

Sounds like the device you mention is measuring the current and voltage and using P=V X I

 

[zoiDman]

I think it was Attypops who mentioned one time that he would like to see a VV/VW that Didn't have a Digital Display. Just Bars or Symbols.

With No Digital Display, a User would just Adjust the PV purely based on the Taste of the Hit.

 

[twgbonehead]

Sounds like the device you mention is measuring the current and voltage and using P=V X I

You can see one on wikipedia. Look at "Wattmeter" and the second image down on the RHS is very similar to the one I got for my brother. (Caption: Early wattmeter on display at the Historic Archive and Museum of Mining in Pachuca, Mexico). They are pretty rare, though.

A regular meter works by sending a small amount of current through a coil. The coil is in a magnetic field. As more current flows, it puts a force on the coil, which moves the needle (working against a spring). In a regular meter, the magnetic field comes from a permanent magnet, (and works against the magnetic field from the current flowing through the coil). So you have a fixed magnetic field working against a variable magnetic field.

In the wattmeter, you have 2 coils. One coil has the current flowing through it. The other has a current proportional to the voltage.
The force between the 2 coils goes as I1*I2 (where I1 is the current in the first coil, and I2 is the current in the second one). Once again, this force works against a spring to move the needle.

Since power = V*I, the meter reads power directly.

(Of course, the above discussion requires using the correct geometry for the coils, but the basic principle is that the magnetic attraction between 2 coils is proportional to (the flux through coil A) * (the flux through coil B), and the flux through a coil is directly proportional to the current.

 

[p.opus]

The point is that there are only 2 things that can limited in an APV, current(amps) or voltage(volts), watts cannot be limited because it can not be measured. A VW device takes the power setting you put in to calculate the voltage needed, it will then deliver the required voltage unless you exceed either the voltage or amperage that the device can deliver.

But this is NOT what the MVP is doing. The limits, as you saw in my numbers earlier do not relate to a specific amp rating, nor do they relate to a specific voltage.

Like I said, The MVP appears to measure the attached coil resistance and then calculate the threshod voltage limit based on a calculated 11 watts and apply that across the board. If your selected voltage is BELOW this threshold, then it will deliver your selected voltage. If the selected voltage is above this threshold, then it will simply deliver the threshold voltage.

In short, the MVP is measuring the coil resistance and setting it's own maximum available voltage based on the resistance of coil installed..

 

[fjgotgame24]

Hmmm...I thought I new what was going on but still a bit confused. One thing thats weird too me is how low ohm coils means less voltage. I thought that low ohms would require more power and more volts, but Ive been running some numbers through conversion sites that say otherwise. Im guessing its a resistance thing where since it has less resistance, it doesnt require as much volts. Then I ask myself, why is not safe to go sub-ohm when it can clearly handle the voltage? Guessing its because of amp limitations??? And if it is amp limitations, why the heck is there an amp limitation when the device is capable of handling the voltage...I thought voltage was "more" important so to speak. I just really want to get the best vape I can get, and I know its a preference thing, but I guess what I mean by that is I want all my settings to be optimal. Volts, Amp, Watts and whatever else Im missing. Basically push for the lowest ohms possible that it can handle, and set either the volts or watts to its highest functional setting possible, and I would assume it would give me the best vape. So if I have my coils @ 1ohm, whats the furthest I can push the wattage/voltage so that its all still functional and there isnt any energy going to waste. Like I dont want a setup where I build something and set the volts to 6 which give me like 60 watts but VTR only handles 15. Theres like 45 watts going to waste is the way Im thinking of it. What is the most balanced voltage + wattage setup that the VTR can handle thats all within its restricted capability I guess is what Im asking. But still kind of on the higher limits of things. Haha Im sorry but I just dont get the equation stuff.

 

[p.opus]

Hmmm...I thought I new what was going on but still a bit confused. One thing thats weird too me is how low ohm coils means less voltage. I thought that low ohms would require more power and more volts, but Ive been running some numbers through conversion sites that say otherwise. Im guessing its a resistance thing where since it has less resistance, it doesnt require as much volts. Then I ask myself, why is not safe to go sub-ohm when it can clearly handle the voltage? Guessing its because of amp limitations??? And if it is amp limitations, why the heck is there an amp limitation when the device is capable of handling the voltage...I thought voltage was "more" important so to speak. I just really want to get the best vape I can get, and I know its a preference thing, but I guess what I mean by that is I want all my settings to be optimal. Volts, Amp, Watts and whatever else Im missing. Basically push for the lowest ohms possible that it can handle, and set either the volts or watts to its highest functional setting possible, and I would assume it would give me the best vape. So if I have my coils @ 1ohm, whats the furthest I can push the wattage/voltage so that its all still functional and there isnt any energy going to waste. Like I dont want a setup where I build something and set the volts to 6 which give me like 60 watts but VTR only handles 15. Theres like 45 watts going to waste is the way Im thinking of it. What is the most balanced voltage + wattage setup that the VTR can handle thats all within its restricted capability I guess is what Im asking. But still kind of on the higher limits of things. Haha Im sorry but I just dont get the equation stuff.

Think of it this way.

Voltage is a measure of potential energy. Now I won't go into what that means, but lets say it's your arms.
Watts is the amount of work I am doing. In this scenario, it's lifting a box. That's my goal...I want to "lift the box"
And resistance is any force that resists me from doing the work.. In this case. it's weight.

Now the work I want to do, is to lift the box.
If the box is empty or has "low resistance" then I need less strength (voltage) to complete the job.

However, If I add weight to the box, then I need more strength (voltage) to do the same work (lift the box).


How does this apply to an e-cig.

I adjust my variable "whatever" to "taste". This number is arbitrary. It's what you like, it's going to be dependant on a lot of things, the design of the tank, whether it's top or bottom fed, the wicking capability of the system.... Any way. I am looking to do some "work" to achieve my desired taste. In electrical terms this is called watts. It is a calculated measurement of power at your coil. Watt = HEAT.

Now to achieve that "taste" or work, I need to apply a voltage. However, my coil (resistance) is going to make achieving that wattage either harder (higher resistance means I need higher voltage) or easier (lower resistance means I need less voltage).

Just like my example of lifting a box, heaver box more strength to lift....ligher box, less strength to lift.

Now if you are still with me, let's apply this to an e-cig battery.

A coils resistance is usually constant, It is based on the type of wire used, how many loops in the coil thickness of the wire...blah...blah blah. Point is it is a static value (for the most part, and for simplicity sake). So I put my 2 ohm coil on my variable voltage battery set it up to 4.0 volts and I'm in heaven. I have discovered how much strength I need to lift the box.

This is what a variable voltage battery allows you to do, it allows you to vary the strength so that you can "lift the box".

I'm a happy camper.

But now I go to change my tank and unknowingly, It's lighter (the coil has less resistance). Well my voltage is still set to 4.0 volts, so when I go to lift the box, I find that now I lift it to fast, throw out my back and taste burnt juice. I applied the same strength to lift a lighter box.

OR I change my tank and it's a heavier box, and when I use 4.0 volts it tastes weak, not very flavorful...Why? Not enough strength to lift the box.

This is kind of like what you do with a variable voltage battery, you are either adjusting it up or down to counteract the fact that the coil is either "heavier" or "lighter".

Ok, I hear you say, what is this variable wattage thing.

Variable wattage is an attempt to limit the adjustment necessary when you change to a "heavier" or "lighter" coil. It's not perfect and really we're not here to argue the benefits or drawbacks of either. It is what it is.

I put on my 2 ohm coil and on a Variable wattage battery I adjust "watts". The battery MEASURES the ohms of my coil, Detects the Watts I have set and then automatically adjusts the strength so that it outputs just enough voltage to reach that wattage calculation. So lets say I put on my tank and adjust wattage to 7.0 watts and I'm in heaven.

Now, I put on a 3 ohm coil. On a variable voltage device, it was up to me to increase voltage manually until I got to my desired flavor. With a variable wattage device, the device senses the coil resistance went up, you are still set to 7.0 watts, so the device will AUTOMATICALLY adjust voltage up again. so that you get 7.0 watts on a 3.0 ohm coil. Now you go back to a 2.0 ohm coil and the battery automatically adjusts voltage down again so you get 7.0 watts at a 2.0 ohm coil.

In short, a variable voltage battery is where I adjust the INPUT so that the battery will give a CONSTANT INPUT regardless of what resistance I put on. 4.2 volts on a 1.5 ohm coils is 4.2 volts on a 2.0 ohm coil is 4.2 volts on a three ohm coil.

A variable wattage battery is where I set a desired OUTPUT, the battery senses the resistance and automatically adjusts voltage to achieve that output.

Example. 7.0 watts on a 2.0 ohm coil. Put on a 1.5 ohm coil, battery lowers voltage to achieve 7.0 watts at the coil. Put on a 3.0 ohm coil battery raises voltage to achieve 7.0 watts at the coil. The OUTPUT stays constant, but the input is automatically adjusted depending on the resistance of the head.

Hope that cleared some things up.

One last thing. A variable wattage/voltage battery does not do both simultaneously. It does one or the other.

If set to variable voltage mode, it will put out the same voltage regardless of the coil resistance.
If set to variable wattage mode, it will vary the voltage to achieve the set wattage.

 

[fjgotgame24]

What about the amp limitation?

Sent from my VS870 4G using Tapatalk

 

[fjgotgame24]

I think I got it... I'll probably adjust my settings with wattage first and let it auto set my volts... then ill probably tune it with the voltage afterwards. I'm expecting my vtr tomorrow, and I'm hoping its a winner. Thanks for the help. *BTW is it normal to be informed about this stuff because I feel like everyone is so knowledgeable or is the vape community that much better than everyone else? I swear I put on my monocle before I begin my nightly run through the forums. Off to rebuildables...Buon pomeriggio!

Sent from my VS870 4G using Tapatalk

 

[SoberSnyper]

But this is NOT what the MVP is doing. The limits, as you saw in my numbers earlier do not relate to a specific amp rating, nor do they relate to a specific voltage.

Like I said, The MVP appears to measure the attached coil resistance and then calculate the threshod voltage limit based on a calculated 11 watts and apply that across the board. If your selected voltage is BELOW this threshold, then it will deliver your selected voltage. If the selected voltage is above this threshold, then it will simply deliver the threshold voltage.

In short, the MVP is measuring the coil resistance and setting it's own maximum available voltage based on the resistance of coil installed..

So you agree, the voltage is being limited. What are we arguing about again.

 

[Capt.shay]

I think I got it... I'll probably adjust my settings with wattage first and let it auto set my volts... then ill probably tune it with the voltage afterwards. I'm expecting my vtr tomorrow, and I'm hoping its a winner. Thanks for the help. *BTW is it normal to be informed about this stuff because I feel like everyone is so knowledgeable or is the vape community that much better than everyone else? I swear I put on my monocle before I begin my nightly run through the forums. Off to rebuildables...Buon pomeriggio!

Sent from my VS870 4G using Tapatalk

Meh, don't sweat it my friend. There is no wrong voltage/wattage. It's about what taste good to you. IMHO VW is more marketing hype than practical. So many things can effect your vape other than the amount of power. Temperature, type of topper, type and age of juice, even your mood or what you have eaten or drunken last. I find myself bumping my Voltage up or down one or two tenths all the time. My suggestion would be to take something like a 2.2 ohm coil and start around 3.5v then bump it up a tenth at a time until it start tasting slightly burnt taste, probably somewhere around 4.3V. This is your range. Now play around within that range to find what the best voltage is for that juice on that topper on that day. You can then convert it to watts if you want and use VW - as long as you don't change juices or the enviormental temperatures don't change and you like the same power out of all your devices, you can "set it and forget it" like the marketing hype claims.

 

[DavidOck]

Or do the same in VW mode. Just start low and take it up in steps. Starts to taste burned, turn it down to the last step.

And don't sweat the amp limits, just keep your coils above, say, 1.8 Ω. Anything less on a VV/VW style is likely to cause problems. If the battery senses too high a demand on it, it will just turn off. (Well, if it's working properly!)

And also don't sweat the math. Adjust to taste. That's why we have VV and VW devices. With a fixed voltage, a plain Ego style or a mech (without a Kick), that's when you need some inkling of the math, since you can't adjust anything except the resistance. And that's not something you do while vaping.

 

[KenD]

And if it is amp limitations, why the heck is there an amp limitation when the device is capable of handling the voltage...I thought voltage was "more" important so to speak.

The battery itself will always give out as much voltage as its charge level is at. A fully charged 4.2v battery will provide 4.2v, and the device will regulate that to whatever voltage you've set it to, basically determining how many "units of 4.2v, or whatever the charge of the battery is, are drawn. So, at the device set to 6v and your battery charged to 4v you're not really drawing 6v out of the battery but rather 1.5 units of 4v.

Amps are the stored energy in the battery and you have a limited amount of that. The amp draw tells you how much of the stored energy you are pulling out at one time, and batteries will have a limit to how much of the energy can safely be drawn in one pull (the battery's a-rating). If you try to pull out more the battery is likely to break, and that's really bad. That's why regulated mods have amp limits.

Basically push for the lowest ohms possible that it can handle, and set either the volts or watts to its highest functional setting possible, and I would assume it would give me the best vape. So if I have my coils @ 1ohm, whats the furthest I can push the wattage/voltage so that its all still functional and there isnt any energy going to waste. Like I dont want a setup where I build something and set the volts to 6 which give me like 60 watts but VTR only handles 15. Theres like 45 watts going to waste is the way Im thinking of it. What is the most balanced voltage + wattage setup that the VTR can handle thats all within its restricted capability I guess is what Im asking. But still kind of on the higher limits of things. Haha Im sorry but I just dont get the equation stuff.

Power (wattage) is a result of voltage put through resistance. At the same voltage higher resistance and you'll use less amps but also get less less power, with lower resistance you'll use more amps and get more power. At the same power setting lower resistance will require more amps, and thus drain the battery faster. So, on a regulated device you'll use up less of the stored energy the more you increase resistance, but as higher resistance means that you need to draw more "voltage units" you'll hit a limit of how high a voltage you can set your device to deliver. For example: A 2.4 ohm coil will give you 15w (the maximum wattage setting) at 6v (the maximum voltage setting) and use 2.5 amps. A 1.2 ohm coil will give you 15w at 4.243v (you can't go higher than that as you've hit the wattage limit) and use 3.536 amps. So, with the 2.4 ohm coil your battery will last longer. If you use a 3 ohm coil you cannot get more than 12w because you can't set the device any higher than 6v (you're now using 2 amps).

Sent from my GT-I9100 using Tapatalk

 

[Capt.shay]

Or do the same in VW mode. Just start low and take it up in steps. Starts to taste burned, turn it down to the last step.

The only reason I say to do it in VV is because you can move it in smaller increments than VW (on the MVP) but other than that, it's all just electrons jogging through a coil.

 

[PaulBHC]

Or do the same in VW mode. Just start low and take it up in steps. Starts to taste burned, turn it down to the last step.

And don't sweat the amp limits, just keep your coils above, say, 1.8 Ω. Anything less on a VV/VW style is likely to cause problems. If the battery senses too high a demand on it, it will just turn off. (Well, if it's working properly!)

And also don't sweat the math. Adjust to taste. That's why we have VV and VW devices. With a fixed voltage, a plain Ego style or a mech (without a Kick), that's when you need some inkling of the math, since you can't adjust anything except the resistance. And that's not something you do while vaping.

Except I do adjust the resistance while vaping because of all the different toppers I have. I didn't know that until I got the MVP and started checking.
I have plain ego 650s. I got an MVP and found it not as good for my work situation as I would like. I like the size of a 650. I got a Vision Slip, simple safe button mod. Got 2 AW 18350 700. My idea was to have something near the size and weight of the ego, but longer battery duration (all day instead of half a day with an ego).
I have dual coil 1.8, dual 2.1, single coil 2.0-2.5
My question is which coil is going to give me the longest time on the 18350? Or should I get a kick or VV ego style?

 

[DavidOck]

Well, yes, changing toppers may change the resistance. Hence VW mode. But even then, it may need to be adjusted for the flavor of the particular liquid.

A 700 mA '350 isn't going to run significantly longer than the 650 ego, but you can carry spares and swap them out, so that might be all you need. I think the single coil toppers will give you longer run time than either of the duals. You could just run a test, with two freshly charged 18350s.