Eleaf Istick

[pcrdude]

Just a primer on how PWM works...

With very few exceptions, PWM (pulse-width-modulation) boosts the battery voltage to a set level, usually the device's highest voltage, sometimes a bit higher. Then it pulses that voltage several times per second to obtain the overall voltage that's been set. In the case of the istick, it apparently boosts voltage to 5.8V (according to an earlier post in the thread). Then it pulses 5.8V 48 times per second (48 Hz). Those 48 pulses per second can be very short or much longer until the output voltage looks constant on test equipment. The percentage of time (per second) that the voltage is on (vs. off) is called it's duty cycle.

The below image shows a device with a peak of 5V firing at 20%, 50% & 75% duty cycles.

View attachment 379587

Here's where it gets kind of tricky... If we multiply the peak voltage (Vpk) by the duty cycle (C%) we get the average voltage (Vavg, shown above). We know that firing a Vavg of 3.5V into our 1.8Ω coil creates much higher Wattage at the coil than a constant 3.5V.

For example, using the iStick's specs:

Ohm's Law (V²/R=W) tells us that a constant 3.5V into a 1.8Ω coil will give us 6.8W.

W also know a different formula is used to determine Watts from a PWM Vavg signal:
(Vpk²/R) * C% = W or in our case, (5.8²/1.8Ω) * (3.5/5.8) = 11.3W

6.8W vs. 11.3W is a big difference.
We use RMS (root-mean-square) Voltage to obtain the Watts that constant Voltage provides.

The iStick appears to be plugging an Average Voltage (Vavg) value into Ohm's Law, rather than an RMS or constant voltage, providing much higher Watts at the coil. If true, it's all about faulty software NOT hardware and could be fixed rather simply and cheaply with upgraded firmware in future runs.

Great post!!!

I'm pretty sure that is exactly what is happening, but we'll need somone to actually measure Vave and Vrms to verify....

 

[pcrdude]

Not the best pic but I think the genitank looks great on this silver one!


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Thanks (now I don't have to post a pic of mine). It still looks good with the supplied drip tip as well.

 

[pbusardo]

Hey guys, just to let you know Joyetech USA did send me the iStick directly. Hope to have the video out to you by the end of the week.

 

[pcrdude]

I don't have any numbers, nor do I understand most of what anyone is saying in this thread in regards to the numbers.

All I know is that at 3.8 volts on my istick, my vape performs similar to the 4.2 volt range if it were on my MVP or my ego twist. When I turn the voltage up above my 3.8 sweet spot, I get warmer vape with diminished flavor, and burn tastes if I take it high enough. I just tried it at 3.5 volts and it still tasted burned on the first hit. Dropping it back down to the minimum 3 volts makes it taste the way it should.

I hope some people who report diminished power are correct here. I'm not a sub-ohmer and never will be. I got the iStick as a smaller replacement to the MVP. Other than the voltage being off, I think I love this thing. It's exactly what I was looking for 3 months ago when I got my MVP. The front trigger button is a nice touch as well.

I don't know what your topper is, but my solution was to use a Kanger BDC Genitank at 1.8 ohms. Even at 3.0 volts indicated, it vapes 50/50 liquid very well. It does go through liquid faster than a Kanger 2.5 ohm single coil set at 3.7 volts.....

Hmmmmm



YMMV

 

[pcrdude]

Hey guys, just to let you know Joyetech USA did send me the iStick directly. Hope to have the video out to you by the end of the week.

AWESOME Phil!!!!!!

So the suppositions and experiences will be scientifically tested.

May I be the first to say THANKS PHIL!!!!!

 

[zoiDman]

Hey guys, just to let you know Joyetech USA did send me the iStick directly. Hope to have the video out to you by the end of the week.

Right On Phil.

Can't Wait to see all the Charts and Graphs and Whatnot.

 

[aznnp77]

I don't know what your topper is, but my solution was to use a Kanger BDC Genitank at 1.8 ohms. Even at 3.0 volts indicated, it vapes 50/50 liquid very well. It does go through liquid faster than a Kanger 2.5 ohm single coil set at 3.7 volts.....

Hmmmmm



YMMV

I'm using a Protank 2 with aerotank base at 2.2 ohms or 2.5 depending on the tank (I have 4 of them). I never said it didn't vape very well. I just said I know for a fact that it's putting out more power than stated on the screen, for now at least. I've only been using it for half a day.

Yay for pbusardo review (see 4 posts up).

I hope phil can explain this in layman's terms so that everyone can understand. Phil is so known and respected among the community that maybe Joyetech will do a recall and fix the firmware or something. I wonder if the istick can be connected to a computer or something.

 

[clnire]

Hey guys, just to let you know Joyetech USA did send me the iStick directly. Hope to have the video out to you by the end of the week.

YES! Thanks Phil, look forward to it.

 

[pcrdude]

I'm using a Protank 2 with aerotank base at 2.2 ohms or 2.5 depending on the tank (I have 4 of them). I never said it didn't vape very well. I just said I know for a fact that it's putting out more power than stated on the screen, for now at least. I've only been using it for half a day.

Yay for pbusardo review (see 4 posts up).

I didn't mean to put words in your post....

;O

For me (50/50), that higher voltage (supposed) is enough to spoil the vape using a single coil @ 2.5 ohms.

 

[zoiDman]

Hey guys, just to let you know Joyetech USA did send me the iStick directly. Hope to have the video out to you by the end of the week.

BTW - At 6:11 in this Video, the Reviewer shows that the Version Number can be Displayed by pressing the Up and the Down Buttons at the Same Time when the APV appears to be Off. But I have Not been able to Replicate this.



Perhaps you can cast some light on How to Display the Version Level of an iStick.

Because it would seem to be of Paramount Importance to know what the Revised Level of the iStick you receive for Review.

Thanks Phil.

 

[salemgold]

Okay but, tell the truth. How many of you guys really have your eyes on the iStick while watching that ^^^^^ review??

 

[YKruss]

Okay but, tell the truth. How many of you guys really have your eyes on the iStick while watching that ^^^^^ review??

What iStick?

 

[Fergie]

Just got my silver one, peeled off the stuff on the display put a Protank Mini II on it at 7 Watts and wow, what can I say. Got it set at 4.5 W with a 2.3 ohm coil.

Lovin' it

 

[MrsP0721]

Just had the hubs put one of those wraps on it... didn't work out as well as my OCD would have hoped but hopefully we'll get a sharper knife and fix it lol.

 

[spartanstew]

Just had the hubs put one of those wraps on it... didn't work out as well as my OCD would have hoped but hopefully we'll get a sharper knife and fix it lol.

Your husband's not the sharpest knife in the drawer?

 

[jafmf95]

What iStick?

Nice tank!

 

[scaredmice]

BTW - At 6:11 in this Video, the Reviewer shows that the Version Number can be Displayed by pressing the Up and the Down Buttons at the Same Time when the APV appears to be Off. But I have Not been able to Replicate this
..../...

Neither could I..... No matter what, each time I press both up and down buttons (when it's on) one of them commands the suitable action (power/voltage goes up or down).

And when it's off (both as screen off and fully off, expecting five clicks to wake up) it simply ignores me....

 

[Katdarling]

Do you remember where you got that black and white drip tip from? I like the ming style drip tips but have been looking for some shorter ones cause they just don't want to quite fit into my case and that black and white one would be perfect!

I don't know where Katdarling got her drip tip, but I've always had a strong preference for short drip tips. Here's a few ideas.

From FastTech:
Acrylic Shorty Drip Tips
Aluminum Shorty Drip Tips
White Teflon Drip Tip
Black/Stainless Drip Tip
Stainless Drip Tip

From RTD Vapor:
Black Delrin Type A

From Empire Mods:
Black Delrin Straight
Ceramic Shorty

From Mad Vapes:
Anodized Super Shorty Drip Tip, Black
Anodized Super Shorty Drip Tip, Silver
Slotted Transformer Drip Tips
Concave Transformer Drip Tips
Short Stainless Drip Tips

Wow, what a great list, DH! Thank you.

Mine was one of my first vape purchases, back in early 2011. It's a "colored and twisted" swirl tip from Nhaler. (#68)

Colored and Twisted 510/901/KR808/N100 Drip Tips

Not the best pic but I think the genitank looks great on this silver one!


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I agree! That looks wonderful, pokemom!

 

[Zanzabar78]

Hey guys, just to let you know Joyetech USA did send me the iStick directly. Hope to have the video out to you by the end of the week.

Great thank you!

 

[Jayscuzzi]

I normally vape at 12w on a 1.5ohm coil which shows 4.2v. I think that's closer to a middle of the road setting than low wattage. I vape with the same settings on other mods with the same results.

I'm doing about the same wattage. Coils I made this go around are about 1.7 to 1.8.
Getting 11 hrs max.3rd full day of using.
I do really love this but I guess I expected longer hours with it.
Holding off on buying a 2nd for myself but did get the wife one and it's on its way.
My 2 main gripes are battery life not long enough for the way I use it and my 510 connection has to be treated with kid gloves. Threads are definitely wonky on mine.

Jay G