Ohms Law and Atomizers

[Plettschner]

Like most of the PV jabber that makes little sense to the uninitiated (i.e., a "Mod" is anything beyond an eGo, dripping into an atomizer with a silica wick, etc.), ultra low coil resistance on something like a Provari or eVic is right up there. Shooting for ultra low resistance on a VV or VW APV makes no sense at all to me. If you have a straight-wired APV (or "mechanical mod", as I guess you would like to call it), then it makes sense. If you have a plain eGo battery, it still doesn't make much sense as I don't see them being able to handle much lower than 1.8-2.0 ohms.

So, let's say you have a 2.0 ohm coil at 3.7 volts, you're drawing about 1.8 amps and using about 6.9 watts... those 6.9 watts are dissipated as heat by your coil.

OK, drop coil resistance to 1.5 ohms at 3.7 volts (imagine the battery here as having unlimited power). Now you're pulling ~2.5 amps and are up around 9.1 watts

But wait, you have a VV APV... turn the voltage up to about 4.3V and you're putting 9.1 watts out of that 2.0 ohm coil, but at 2.1 amps now.

1.5 ohm coil at 3.7 volts or 2.0 ohm coil at 4.3 volts... what's the difference?



Just rambling I suppose...

 

[tj99959]

Most Pv's have amp limits and won't allow you to use ultra low resistance, so you can't even if you wanted to. With your ego's going to low with the resistance will just burn out the misfit ckt, and they can then go into the trashcan. Your better APV's will just give you an error code, and not fire.
With mechanical mods the battery will determine what is real and what is a figment of someones imagination. Most of the time the output isn't nearly what someone thinks it is.
Here's an example using a cheap battery:
18500 EH IMR - 1.7 ohm load

3.58 volts only equals 7.5 watts
With more load (lower resistance) the voltage would be even lower

Same battery 1.4 ohm load

 

[zoiDman]

...

1.5 ohm coil at 3.7 volts or 2.0 ohm coil at 4.3 volts... what's the difference?


Just rambling I suppose...

Watt wise? Nothing. At least to Two Decimal places. But as mentioned, there has to be a Change in Amps to Satisfy Ohms Law. Sounds like a Conservation of Energy thing to Me.

So the Amps change. This could Exceed the Limit of your VVPV. Not Good. Or it could Exceed the Limit of your Batteries. Bad.

Also, since this is the Real World and Not some Text Book Example where all the other Factors are removed, using the Same Watts but Different Volts/Current can give a Different Hit.

 

[Plettschner]

I think that's where I was going... I ignored several factors/variables (connector losses, battery internal resistance, etc) intentionally for simplification purposes. I don't see myself ever going to straight-wired APV route... just doesn't make sense to me. We're using crude enough equipment, why go even further in reverse. I understand the less to go wrong with simple machines, but there cannot be any consistency to a straight-wired battery circuit. I'm more of a buck-boost kind of guy where I could get the consistency of a constant voltage/wattage circuit... at least within what the battery can supply. Then again, any juice I have tried over 7 watts tastes like ... to me, but I suspect that is just my crappy equipment.

In the real world, is there actually a difference between 9 watts at 3.7 volts or 9 watts at 4.3 volts?

 

[Non-Smoking]

I hooked my NJOY cartomizer up to my car battery. It was awesome, amazing throat hit

 

[tj99959]

Watt wise? Nothing. At least to Two Decimal places. But as mentioned, there has to be a Change in Amps to Satisfy Ohms Law. Sounds like a Conservation of Energy thing to Me.

So the Amps change. This could Exceed the Limit of your VVPV. Not Good. Or it could Exceed the Limit of your Batteries. Bad.

Also, since this is the Real World and Not some Text Book Example where all the other Factors are removed, using the Same Watts but Different Volts/Current can give a Different Hit.

What will change is how fast the coil reaches optimum temperature. This is why we sometimes need to take a few short puffs to warm things up a bit with some setups.

 

[Plettschner]

I hooked my NJOY cartomizer up to my car battery. It was awesome, amazing throat hit

LOL! Did you fill the carto with Tiki Oil first? I hear that works best with a car battery!

 

[zoiDman]

I think that's where I was going... I ignored several factors/variables (connector losses, battery internal resistance, etc) intentionally for simplification purposes. I don't see myself ever going to straight-wired APV route... just doesn't make sense to me. We're using crude enough equipment, why go even further in reverse. I understand the less to go wrong with simple machines, but there cannot be any consistency to a straight-wired battery circuit. I'm more of a buck-boost kind of guy where I could get the consistency of a constant voltage/wattage circuit... at least within what the battery can supply. Then again, any juice I have tried over 7 watts tastes like ... to me, but I suspect that is just my crappy equipment.

In the real world, is there actually a difference between 9 watts at 3.7 volts or 9 watts at 4.3 volts?

When I started using e-Cigarettes, all the Batteries were Unregulated. So right off the Charger they worked well. But as I used them, the hit got Weaker and Weaker. That is my problem with an Unregulated Mechanical Mod.

Regulated PV's were Huge and solved this Problem. But to Adjust the hit, you had to select Different Ohms for your Atty/Carto/Clearo. And the Consistency of one Atty/Carto/Clearo to the next was Hit or Miss many time.

When I went to VV, all this went away. But the Issue of Same Watts with Different Volts/Current started to be talked about.

My thought is though the Watts may be the same, the Time it takes a Coil Wire to Heat Up and then Cool effects they way a Hit Tastes.

Using the Same Watts, I can look at an Empty/Dry atomizer wire and see that it Changes Color (Temperature) at a Different rate/pattern when I hit the power button on a VVPV.

The Problem is that Hit Taste is an Subjective Concept. And Hard to Quantify. So where I can see from Observations that the Coil Wire is Heating Differently with Respect to Time, I can't say what is Good Or Bad for any Given Person.

---

I'm also in the 7 Watts or Less Crowd for the Clearos I use and the e-Liquids I put in them.

 

[zoiDman]

What will change is how fast the coil reaches optimum temperature. This is why we sometimes need to take a few short puffs to warm things up a bit with some setups.

Length of the Wire and the Diameter of the Wire. And or Both.

I have seen some Clearo that when I Dry Burn them they Heat Up and turn Orange at the Same Rate across the Coil Loops. They all Turn Orange at the Same Time. These give Me the Best Hits.

But I have others where the Loops on the Ends turn Angry, White Hot before the Center Loops turn Orange. These give Me the Worst Hits.

 

[Plettschner]

Interesting... I would have thought that 9 watts is 9 watts is 9 watts and the coil would heat and cool exactly the same. I have to wonder if it's more of a battery and/or circuitry limitation than anything else that would cause the difference in heating cooling rates... or perhaps the coil wire length/wire gauge play more of a factor.


EDIT: looks like you beat me to it... I'm trying to reply with a 4 year old next to me!

 

[Plettschner]

Dry burning a clearo... doesn't that scorch the crap out of the wick?

 

[zoiDman]

Interesting... I would have thought that 9 watts is 9 watts is 9 watts and the coil would heat and cool exactly the same. I have to wonder if it's more of a battery and/or circuitry limitation than anything else that would cause the difference in heating cooling rates... or perhaps the coil wire length/wire gauge play more of a factor.


EDIT: looks like you beat me to it... I'm trying to reply with a 4 year old next to me!

9 Watts is 9 Watts.

If it Isn't, Maxwell would turn over in his Grave.

But what are Watts? And do Watts Alone determine how Good or Bad a Hit Tastes?

There a Dozens of threads here on the ECF, mainly in the Re-Buildable Atomizer (RBA) section, where people have discussed the Difference in Performance and Taste using Different Wire Gauge/Length and the Amount of Loops/Winding for the same Watts.

Heating and Cooling adds another Dynamic to a Surprisingly Complex concept of an Atomizer Wire.

If I Heat a Straight Wire does it Cool Down at the Same Rate as the Same Wire that is Loop around Something? What is the Loops are Close together? What is they are Far Apart? What if the Loops are Tightly Wound? What if they are Relatively Loose?

Maybe I can't make a Quantified Answer to Each Example. But is it Good Enough to say that there is a Very High Probability that Each will be at Least Different?

 

[zoiDman]

Dry burning a clearo... doesn't that scorch the crap out of the wick?

Pure Silica Wicks Don't Burn at Dry Burn Temperature.

 

[Plettschner]

Good stuff... thanks for the insight.

 

[AttyPops]

Thermodynamics are missing. For all of us.

The SLR guys use thick wire...they need lots of watts to just barely begin to heat it. Compare that with standard coils that are thinner and heat easier. Then there's surface area of the wire contacting the wick. Then coil type (flat or round) is a discussable item. ....

Not all coils perform the same for a given wattage. Particularly new coils vs older used coils even for the same make/model. Gunk and such.

At least that's my very limited understanding and

In general watts are watts for standard stuff. But there's so much variety now.....who knows. This all makes VW interesting if you swap a large variety of stuff. For mostly-same stuff VW is probably great. For diff stuff, adjust anyway.

 

[zoiDman]

Good stuff... thanks for the insight.

No Problem.

But like with all things your Read on a Forum or the Internet, make your Own Conclusions based on what You Observe.

 

[zoiDman]

...

Not all coils perform the same for a given wattage. Particularly new coils vs older used coils even for the same make/model. Gunk and such.

...

You got that Right Atty.

And then throw in all the Possible PG to VG Combinations and Viscosities, it becomes Mind Boggling.

 

[Plettschner]

We need fricken lazer atomizers!!

 

[zoiDman]

We need fricken lazer atomizers!!

I'm working on a Blu-Ray Mod as we speak.

 

[Plettschner]

Funny though, I'm sure it's possible to do (maybe not with a Blu-Ray laser)