Variable Volts-Watts and Ohms Question

[fjgotgame24]

So I have a VTR otw and am trying to think of the best setting I would like. Im a bit confused though because since it has the option to adjust the volts and the watts, does that mean that there different? I was converting some numbers on a website and it said that if I have my settings to 6 volts, which is the max, on a 1.2 ohm coil, I will be @ 30 watts. However the VTR is only capable of going 15 watts so I don't see how this works out. Also, if I max out my watt settings to 15, doesnt that mean my volts also automatically go up too or are they each there own thing? I was under the impression that they were both just a way to measure power output but some devices were variable wattage and others variable voltage. Idk...Im kind of new to the vv/vw stuff.

 

[p.opus]

Think of it as two separate devices....

When in Variable Wattage mode, the device ignores what you set for voltage.

When in Variable Voltage mode, the device ignores what you set for wattage.

In variable wattage mode, you are setting the desired output wattage to be delivered to the coil. The device will read your coil resistance and calculate the voltage required and then automatically adjust voltage of the device to maintain the desired wattage.

In Variable voltage mode, you are setting the output voltage of the device. The device does not take a look at the resistance and will simply provide the desired voltage.

Now there are limitations especially in low ohm coils.

For example, my MVP has an 11 watt maximum limitation regardless of my voltage setting, so If I am in Variable Voltage mode and choose a voltage that will result in a total wattage that will exceed the 11 watt limit of the device, then the device will simply fire at the max voltage that produces 11 watts on the coil resistance. This will cause the device to under fire the set voltage.

The device may also over fire low ohm coils. For example If I am in variable wattage and set to 6.0 watts, on a low ohm coil. If the calculated voltage is less than 3.3 volts (the minimum of my device) then the device will simply fire the coil at 3.3 volts, thus overfiring the coil.

This is why a lot of regulated mods don't like low ohm coils. Lower ohm coils often will be under fired in Variable Voltage if set to higher voltages and over fired in Variable Wattage mode if set to low wattage in variable wattage mode.

 

[fjgotgame24]

That completely cleared up everything. I was watching pbsuardos video on this device and he pulled out a graph that explained exactly what you said but it was confusing. Now that I see your version of it I can put the two together and it makes a lot more sense, thanks, I really appreciate the help.

 

[edyle]

So I have a VTR otw and am trying to think of the best setting I would like. Im a bit confused though because since it has the option to adjust the volts and the watts, does that mean that there different? I was converting some numbers on a website and it said that if I have my settings to 6 volts, which is the max, on a 1.2 ohm coil, I will be @ 30 watts. However the VTR is only capable of going 15 watts so I don't see how this works out. Also, if I max out my watt settings to 15, doesnt that mean my volts also automatically go up too or are they each there own thing? I was under the impression that they were both just a way to measure power output but some devices were variable wattage and others variable voltage. Idk...Im kind of new to the vv/vw stuff.

VW is the upgrade to VV.

With VW you set the wattage, and the device figures out the voltage for you.

The typical coil runs at around 5 watts, so you can safely set 5 watts and leave it there or tweak to taste.
When you change your coil, if its a different resistance than the one you just took out, your device will detect the resistance and adjust voltage to suit.

With VW you don't have to be checking your resistance and adjusting voltage whenever you change coil.

 

[p.opus]

That completely cleared up everything. I was watching pbsuardos video on this device and he pulled out a graph that explained exactly what you said but it was confusing. Now that I see your version of it I can put the two together and it makes a lot more sense, thanks, I really appreciate the help.

Yeah, pbusardo usually states these as "amperage limitations" but they are not.

On a VV only device (like the ProVari) you only have three limits; minimum voltage, maximum voltage and maximum amps. Therefore any limitations that show up are clearly amperage limits.

However on a VW device, you may also have Maximum Wattage.

This may not be the case in ALL devices, but on a lot of them the numbers I saw on his videos never made sense until you added the possibility that some of the Voltage limitations on lower ohm coils could not be mathematically due to an amperage limit. However, once you added the fact that a wattage limitation may still exist even in variable voltage mode then the numbers started making sense. This also explained why some coils over fired in variable wattage mode and the device simply fired the device at it's minimum voltage setting.

 

[DavidOck]

Watts, actually, are a mythical beast.

A convenient way to consider total power used in a circuit.

Watts = Volts x Amps. (Or = Volts squared divided by Ω) So you can get 10 watts by putting out 1 volt at 10 amps, or 5 volts at 2 amps, or...

The device is going to measure the amps, as watts can not be measured, only calculated.

So watt limitations are because of amp limits, regardless of the mode of VV or VW.

 

[Dfinch]

So, sort of back to the OP's question...if the VTR has the reported 5 amp limit and 6 volt max, and there is no wattage limit except the 15 watt limit in power mode because watts can't be measured by the device and are only calculated from volts and resistance...the VTR set at 6 watts should be able to fire a 1.2 ohm coil at 30 watts?

It wouldn't surprise me if there really was a "safety" check on the resistance even in power mode, but if there's no voltage throttling as long as output is under 5 amps then it should mathematically hit 30 watts in voltage mode with a 1.2 ohm coil. I've been wondering about this myself.

 

[DavidOck]

No doubt the regulation circuit has some way to clamp to total watt output at whatever the amp limit is regardless of desired voltage. How else could it have a safety / overload shutdown protection?

With your example numbers, it theoretically should be able to do that, at 6 volts, if it has a 5 amp limit, yes. But the control may throttle the voltage back. Perhaps get an inline voltage tester to see what's really coming out?

 

[p.opus]

No doubt the regulation circuit has some way to clamp to total watt output at whatever the amp limit is regardless of desired voltage. How else could it have a safety / overload shutdown protection?

With your example numbers, it theoretically should be able to do that, at 6 volts, if it has a 5 amp limit, yes. But the control may throttle the voltage back. Perhaps get an inline voltage tester to see what's really coming out?

If you look at the numbers that pbusardo does on the MVP2 in his review, you can see that the numbers are not really consistent with the 3.5 amp cutout that is listed in the manual. However if you do the calculations then they do seem to bear out an attempt by the device to maintain 11 watts.

If you look at his numbers in variable voltage mode, the voltage limitations do not calculate at all to a 3.5 amp limitation or any static amp limitation for that matter. However it does seem to indicate a limiter right around the 11 watt range.

1 ohm, 3.3 volts max voltage achieved, calculates to 3.3 amps and 10.89 watts
1.5 ohms 3.9 volts max voltage achieved calculates to 2.6 amps and 10.14 watts (if the read ohms is off by .1 at 1.4 actual, this number changes to 2.78 amps and 10.86 watts)
2.0 ohms 4.7 volts max voltage achieved calculates to 2.35 amps and 11.045 watts

Surprisingly, this almost mirrors the MVP 1 which was a variable voltage only battery.

In Variable Wattage, Pbusardo, shows the 1 ohm coil always firing at 3.3 volts regardless of the wattage setting. Of course this makes sense since the MVP can't adjust lower than 3.3 volts, so the variable wattage setting will be inconsequential.

What I think is occurring on the MVP is that there is a normal limiter at 11 watts. As resistance lowers, it will continue to lower voltage to maintain 11 watts. If the coil resistance drops further that it can no longer compensate by lowering voltage, the device will continue to fire at 3.3 volts until it draws 3.5 amps and then shut down.

So I think the device has a operating limit of 11 watts regardless of the amps being drawn, and a shutdown at 3.5 amps if it can't maintain below 11 watts.

 

[papapit]

mine only has voltage to worry about.. i usually vape at a 4.5-5.5 seems to be best for flavor and vapors..

 

[edyle]

So, sort of back to the OP's question...if the VTR has the reported 5 amp limit and 6 volt max, and there is no wattage limit except the 15 watt limit in power mode because watts can't be measured by the device and are only calculated from volts and resistance...the VTR set at 6 watts should be able to fire a 1.2 ohm coil at 30 watts?

It wouldn't surprise me if there really was a "safety" check on the resistance even in power mode, but if there's no voltage throttling as long as output is under 5 amps then it should mathematically hit 30 watts in voltage mode with a 1.2 ohm coil. I've been wondering about this myself.

•Variable Voltage: Voltage can be adjusted from 3.0 – 6.0 volts in .1 volt increments
•Variable Wattage: Wattage can be adjusted from 3.0 – 15.0 W in .5 watts increments
•Built-in 3 digit display (Ohms meter, Volts /Watts, atomizer voltage output)
•Maximum current output: 5A

No you can set 6 volts on a 2.4 ohm coil and get 15 watts; but if you put lower than the 2.4 ohm, the device just wont actually be able to deliver the 6 volts under load.
So with a 1.2 ohm coil I would guess you'd end up with a max of 15 watts possible, which means a voltage of 4.2 volts under load.

 

[Dfinch]

No you can set 6 volts on a 2.4 ohm coil and get 15 watts; but if you put lower than the 2.4 ohm, the device just wont actually be able to deliver the 6 volts under load.
So with a 1.2 ohm coil I would guess you'd end up with a max of 15 watts possible, which means a voltage of 4.2 volts under load.

No you can set 6 volts on a 2.4 ohm coil and get 15 watts; but if you put lower than the 2.4 ohm, the device just wont actually be able to deliver the 6 volts under load.
So with a 1.2 ohm coil I would guess you'd end up with a max of 15 watts possible, which means a voltage of 4.2 volts under load.

Thanks for the explanation. If I'm understanding correctly, then, the only advantage of the 5 amp limit compared to regulated mods with a lower amp limit is it can fire a lower ohm cool without an error, but will throttle voltage to keep from exceeding the 15 watt limit. That would explain why the VTR has been shown to fire as low as .8 ohms, even if there's probably no inherent advantage to it since it's still only 15 watts and getting voltage throttled to maintain that limit (at about 3.4 volts and 4.3 amp draw if I did the math right). Is that right? My brain hurts.

 

[Dfinch]

Looking at the charts in pbusardo's VTR review it all makes sense now. Thanks for the learnin'!

 

[edyle]

Thanks for the explanation. If I'm understanding correctly, then, the only advantage of the 5 amp limit compared to regulated mods with a lower amp limit is it can fire a lower ohm cool without an error, but will throttle voltage to keep from exceeding the 15 watt limit. That would explain why the VTR has been shown to fire as low as .8 ohms, even if there's probably no inherent advantage to it since it's still only 15 watts and getting voltage throttled to maintain that limit (at about 3.4 volts and 4.3 amp draw if I did the math right). Is that right? My brain hurts.

•Variable Voltage: Voltage can be adjusted from 3.0 – 6.0 volts in .1 volt increments
•Variable Wattage: Wattage can be adjusted from 3.0 – 15.0 W in .5 watts increments
•Built-in 3 digit display (Ohms meter, Volts /Watts, atomizer voltage output)
•Maximum current output: 5A

3 v 15 watts
15 = 9/r
r = 9/15 = 3/5 = 0.6 ohms

It means it should be able to go down to 0.6 ohms

6 v 15 watts
15 = 36/r
r = 36/15 = 12/5 = 2.4 ohms
It can go as high as 2.4 ohm coil (above 2.4 ohms it will still work, but not at 15 watts)

 

[p.opus]

I know this is something that seems to be a trend with Innokin products. The reviews of the Vamo/Vmax etc that use the same chipset do not seem to experience the same behavior, their limitations seem to be related to the battery itself. When using stacked 18350's these type devices hit their respective voltage settings.

I believe in the case of the 134, Coolfire 2, VTR and SVD, this may just a limitation of the actual battery you use. On the vv3 and MVP I think Innokin is limiting output to 11 watts, or the circuitry they use in these two products limit the output to 11 watts.

 

[edyle]

I know this is something that seems to be a trend with Innokin products. The reviews of the Vamo/Vmax etc that use the same chipset do not seem to experience the same behavior, their limitations seem to be related to the battery itself. When using stacked 18350's these type devices hit their respective voltage settings.

I believe in the case of the 134, Coolfire 2, VTR and SVD, this may just a limitation of the actual battery you use. On the vv3 and MVP I think Innokin is limiting output to 11 watts, or the circuitry they use in these two products limit the output to 11 watts.

What is this trend or behaviour that you are referring to?
I get the feeling there's more of a disconnect or misclarity in the way they report the specifications.

 

[p.opus]

What is this trend or behaviour that you are referring to?
I get the feeling there's more of a disconnect or misclarity in the way they report the specifications.

I think you are right. With Innokin, MVP and VV3 devices there appears to be 4 limits that the device has regardless of what mode the unit is in.

1. The battery will not go below 3.3 volts, regardless of the watts setting.
2. The battery will not fire above 5.0 volts, regardless of the watts setting.
3. The battery will not allow more than 11 watts output regardless of the voltage setting.
4. The battery will not fire at all if 3.5 amps drawn.

I first thought that you could push the watt limit past 11 by using a lower ohm coil and use variable voltage mode to output greater. I also thought you could adjust voltage lower than 3.3 by going to variable wattage mode and setting 6.0 watts in variable wattage mode.

The numbers don't support this, but do support the 4 limits I mentioned above. It appears that uses this same type of regulation in their VTR, SVD, and 134.

With a Sigelei, Vamo, or device using the same chipset, it appears the limitations shown in pbusardo reviews are actual physical limits of the battery being used because stacked 18350's do not have this behavior. Innokin seems to be a little more aggressive in it's regulation.

 

[SoberSnyper]

If you look at the numbers that pbusardo does on the MVP2 in his review, you can see that the numbers are not really consistent with the 3.5 amp cutout that is listed in the manual. However if you do the calculations then they do seem to bear out an attempt by the device to maintain 11 watts.

If you look at his numbers in variable voltage mode, the voltage limitations do not calculate at all to a 3.5 amp limitation or any static amp limitation for that matter. However it does seem to indicate a limiter right around the 11 watt range.

1 ohm, 3.3 volts max voltage achieved, calculates to 3.3 amps and 10.89 watts
1.5 ohms 3.9 volts max voltage achieved calculates to 2.6 amps and 10.14 watts (if the read ohms is off by .1 at 1.4 actual, this number changes to 2.78 amps and 10.86 watts)
2.0 ohms 4.7 volts max voltage achieved calculates to 2.35 amps and 11.045 watts

Surprisingly, this almost mirrors the MVP 1 which was a variable voltage only battery.

In Variable Wattage, Pbusardo, shows the 1 ohm coil always firing at 3.3 volts regardless of the wattage setting. Of course this makes sense since the MVP can't adjust lower than 3.3 volts, so the variable wattage setting will be inconsequential.

What I think is occurring on the MVP is that there is a normal limiter at 11 watts. As resistance lowers, it will continue to lower voltage to maintain 11 watts. If the coil resistance drops further that it can no longer compensate by lowering voltage, the device will continue to fire at 3.3 volts until it draws 3.5 amps and then shut down.

So I think the device has a operating limit of 11 watts regardless of the amps being drawn, and a shutdown at 3.5 amps if it can't maintain below 11 watts.

A device that can measure power(watts) does not exist. In a DC circuit you can only measure voltage(volts), amps(current), and ohms(resistance). Power cannot be measured only calculated using Ohms law as DavidOck said previously, so there is no way to limit a device using watts as it cannot be measured.

 

[p.opus]

A device that can measure power(watts) does not exist. In a DC circuit you can only measure voltage(volts), amps(current), and ohms(resistance). Power cannot be measured only calculated using Ohms law as DavidOck said previously, so there is no way to limit a device using watts as it cannot be measured.

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.

 

[twgbonehead]

A device that can measure power(watts) does not exist. In a DC circuit you can only measure voltage(volts), amps(current), and ohms(resistance). Power cannot be measured only calculated using Ohms law as DavidOck said previously, so there is no way to limit a device using watts as it cannot be measured.

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.