Please help me understand this voltage thing :(

[shamrette]

Hi!

I just bought a variable voltage spinner, and now I'm incredibly confused.
You see, if you look at this voltage chart:
http://www.evcigarettes.com/product...vaping-power-voltage-resistance-ohm-chart.jpg

... it turns out that vaping a 1.8 ohm at 3V is the same wattage than vaping a 3.2 ohm at 4V.
So my questions obviously is what's the point of that, and would you notice any difference when vaping either on the same kit?

Thank you!

 

[Hoosier]

Why not change the voltage and leave the 1.8 Ohm on?

I don't see much of a reason to change the resistance when changing the voltage to keep the same wattage either, but there may be a slight change due to the increased number of coil wraps on the higher resistance one. Can't imagine it would be noticeable under nearly all circumstances though.

 

[shamrette]

Thank you Hoosier. Is it then preferable to vape at 3V / 1.8o ? Does it use less battery or something? I'm confused as you can tell

 

[Beccca]

I;m no expert! I spin the dial til it tastes good. Period.

 

[ImThatGuy]

Thank you Hoosier. Is it then preferable to vape at 3V / 1.8o ? Does it use less battery or something? I'm confused as you can tell

I would think so...after all...using less volts to power anything would mean using less energy from the battery...but i'm no electronic expert...

 

[Ken62]

I agree with Beccca, turn the dial until you are happy. If the juice tastes burned or you pop a coil, the volts are too high. I generally use a 1.8 ohm coil on a twist and have never popped a coil, even at max voltage but I HAVE tasted burning ejuice! haha

 

[Hoosier]

Thank you Hoosier. Is it then preferable to vape at 3V / 1.8o ? Does it use less battery or something? I'm confused as you can tell

No, not really, the battery holds so much power. Power is usually measured in watts, but since batteries have a fixed voltage they are usually rated in current capacity. Batteries hold power, we use power, so it's all good.

Altering the voltage above the 3.7 volts, nominal, from the battery supply should reduce the charge a bit quicker due to circuit losses, but it will be a hard thing to notice to the user.

 

[Kanj.nguyen]

As far as i know, at the same wattage, using higher voltage will make your battery last longer.

If i havent forgotten high school physics, the formula goes something like this:

E= Q x V

So then

Wh= mAh x V/1000
=> h= (mAh x V/1000W)

With h being how many hours you can run your coil at the designated Wattage

All in all, running 4V with a 3.2 ohm head means bettery battery life.

In theory, the difference is significant. Between the 2 options you proposed, the high voltage- high resistance option gives you 33.3% more battery life.

 

[NamVet68]

There are NO hard & fast rules for "Ideal" voltage for every device & user. A lot depends on the juice you are vaping, equipment you use, & personal preferences. To me, a "sweet" type juice is typically better at a lower voltage, while tobacco flavors tend to taste better at a slightly higher voltage (again - at least to me).

Try it yourself: take some of your favorite liquid & turn the dial, take a pull, & adjust it again ...you will most likely be able to taste a difference. When you get it too high, you will know (it will taste burnt).

Just play with it for a while & you will find your "sweet spot".

 

[Magma]

As someone new to VV/VW, I have an Evic and have been playing around until I find a sweet spot as far as Vapor production and flavor

 

[Hoosier]

As far as i know, at the same wattage, using higher voltage will make your battery last longer.

If i havent forgotten high school physics, the formula goes something like this:

E= Q x V

So then

Wh= mAh x V/1000
=> h= (mAh x V/1000W)

With h being how many hours you can run your coil at the designated Wattage

All in all, running 4V with a 3.2 ohm head means bettery battery life.

In theory, the difference is significant. Between the 2 options you proposed, the high voltage- high resistance option gives you 33.3% more battery life.

Your formula only works that way if you can change the battery voltage, but that is fixed so a boost circuit increases the voltage. To simplify it, the circuit uses current to increase the voltage and the circuit is not 100% efficient so there are additional losses there. It makes more since to look at it through Power Law and realize the battery is a power storage device with a fixed voltage and just rated with current capacity to simplify a designer's life. (It also comes into play with C ratings and discharge rates, so it's nice to have that info up front when you're designing circuits, but it does lead some to confuse a battery for a current storage device.)

 

[sawlight]

As far as i know, at the same wattage, using higher voltage will make your battery last longer.

If i havent forgotten high school physics, the formula goes something like this:

E= Q x V

So then

Wh= mAh x V/1000
=> h= (mAh x V/1000W)

With h being how many hours you can run your coil at the designated Wattage

All in all, running 4V with a 3.2 ohm head means bettery battery life.

In theory, the difference is significant. Between the 2 options you proposed, the high voltage- high resistance option gives you 33.3% more battery life.

Your formula only works that way if you can change the battery voltage, but that is fixed so a boost circuit increases the voltage. To simplify it, the circuit uses current to increase the voltage and the circuit is not 100% efficient so there are additional losses there. It makes more since to look at it through Power Law and realize the battery is a power storage device with a fixed voltage and just rated with current capacity to simplify a designer's life. (It also comes into play with C ratings and discharge rates, so it's nice to have that info up front when you're designing circuits, but it does lead some to confuse a battery for a current storage device.)

As Hoosier stated, this only works in theory when reducing voltage, say you start with 7.4v and drop it down, but there is still some loss in the regulation circuit, but minimal.
Now is when things get funky. YES, it requires less amperage at higher voltage, but the battery, as stated above, is fixed voltage. Then we only achieve 85% effacy (general know loss factor), so we loose 15% right off the bat. BUT, this even happens when we run at 3.7v and lower.
I haven't done the tests, and have no means to do so accurately, but I believe I get more run time at higher voltage. Maybe because I believe it to be, I don't know? But in reality, it should come out as a wash either way because the base voltage is always the same.

As to the OP, yes, it's the same watts in both cases, this is the beauty of VV, you can use what you have to get what you want/like!

 

[Hoosier]

Good point. A buck circuit doesn't have to as loss-y, but that usually requires a narrow delta range. There are exceptions, but well designed buck circuit dropping a 2 cell voltage down would have fewer losses than boosting it up from a single cell.

There are issues with series rechargable batteries though, but the RC crowd has a host of solutions available for them. May be a bit before it moves over to vaping.

OK, where will this thread go next?

 

[Kanj.nguyen]

I think we have managed to confuse the OP more than he is. Or possible has ever been

 

[Hoosier]

Well we could go into phase relationships or something that uses square roots and just completely derail the thread.

 

[shamrette]

I think we have managed to confuse the OP more than he is. Or possible has ever been

Oh excuse me, where am I again? What is this place? Who am I?

I think I'll go vape and rotate the dial now.

 

[The Ocelot]

Oh excuse me, where am I again? What is this place? Who am I?

I think I'll go vape and rotate the dial now.

I can do math an' stuff (even without taking my shoes off), but... add 2 to the resistance (for example 1.8 + 2 = 3.8) set the volts at the result (3.8 in this example) and slowly dial up or down to suit your taste. It's just a rough starting point for single coil cartos. IMO