New Lavatube Tech Stuff

[Blitzer]

Don't have permissions to post this in the Lavatube forum so...

I think I have this Lavatube V.1.5T, or whatever you call the new one figured out.
I am talking about the new lavatube with the same colored buttons as the body, resitance checking,
zombie shutdown mode, etc...

I am an electronic technician. Hope this finds other techy people to refine...
I have a tektronix oscilloscope, which I used to see the voltage unloaded.
At 3 volts on the LT display I got 3.1 volts on a voltmeter. The scope showed
a 6.2 volt peak pulse. The pulses on the scope were 50% duty cycle. (Half of the time 6.2 volts,
the other half of the time 0 vdc) The pulse train (PRF) seems very stable at 100 hz, or 10 msec per prt.
The pulse width "on time" changes based on the volts I set on the lavatube display.
Example: I set the LT to 4.2 volts. 4.2v avg / 6vpk = .7 (70% duty cycle).
THe real peak voltage on MY LAVATUBE unloaded is 6.2V, so 6.2V * .7 duty cycle is 4.34v avg. (What I get)
Volts displayed Duty Cycle Real pk V Volts measured
3.0 50% 6.2v 3.1
4.0 66.7% 6.2v 4.13
5.0 83.3% 6.2v 5.16
6 100 6.2v 6.2
So the PWM scheme seems straight forward to me. How about under load?

I measured 5.338 Vpk on a 3 ohm carto, with the display at 6 volts.
The other voltage settings on the lavatube just changed the pw, as I have described above.
The 5.338 Vpk was always the same. Likewise, on a 2.2 ohm carto I got 4.57 Vpk.
Hmm, where was this changing peak voltage coming from? The PWM scheme stays the same
for all the settings I tried, only the peak voltage changed based on resistance of carto/attomizer.
I put some Hypnotic Mist on my Lavatube, then vaped and pondered...

What if the LT was trying to stay at 9.5 Watts? I tried this theory on a bunch
of different carto resistances and it seems to work perfectly.
Example: (3 ohms)

Step 1: 9.5 watts / 3 ohms = 3.16666666 ("I squared") (p/R=I^2)
Step 2: Sq root of I squared = 1.779513042 amps (get I from I squared)
Step 3: 1.779513042amps * 3 ohms= 5.338 Volts (WooHoo! Thats what I measured)

Example 2: (2.2 ohms) You do the math, I'll just give answers...
Step 1: 4.3181818
Step 2: 2.078023536
Step 3: 4.57 Volts. Again, the same as my measurement

If you figure the peak voltage, based on your carto resistance- that will be what you get
at the 6 volt setting on the lavatube. Settings below the 6 volt one will be scaled down
from this peak voltage by duty cycle, as average voltage.

Example: I have a 2 ohm carto, and I have 4.5 volts on the display. what voltage do I really have?
A 2 ohm carto has 4.35 volts peak possible voltage at the 6 volt setting.
the duty cycle for 4.5 volts is 4.5/6= .75
A .75 duty cycle (because I have 4.5 volts on display) * 4.35 volts (because this is the max I can get with a 2 ohm carto)
gives us an answer of 3.26 volts. This is what you measure with a 2 ohm load.

I could go on, but here is a fine point: From this math, I can see that the new lava tube is most likely
regulated to be below 9.5 watts. Maybe yours is actually 10 or 9 watts, mine is 9.5 watts.
If you had a 3 ohm carto (5.338vpk) on a lavatube showing 4.5v (.75 duty cycle) you would get
an average voltage of 4.0035 volts, same as a freshly charged EGO right??????
Well, the average voltage is the same BUT- the lavatube is spending half it's time putting out 5.338 volts.
You feel like it's really kicking compared to the EGO.
For the same reasons as pulse width modulation is used on motor control circuits, the PWM here gives more
low end torque in the form of vapor, heat, and kick.

The practical limits of this thing seem to be at the low end: a 1 ohm carto will get 3 amps. Probably a limit.
At the other end you reach 6 -ish volts peak voltage with a 4 ohm carto. Volts wont go up any more, so higher ohms
will be less vape.

Sorry if this was too technical. Feel free to rip me on any typos or technical errors!

 

[SikVapor]

Layman's terms?

 

[Blitzer]

I knew this would be way too technical for most folks, but felt this research needed to be done.

I guess the thumbnail sketch would be:

The new Lavatube acts like it is wattage regulated under the hood. 9.5 watts on mine.

The current limit everyone is confused about (4 amps, 3.2 amps, 2.6 amps)- seems to be 3amps. (at 1 ohm)
Haven't seen any cartos less than 1.25 ohms, so I can't test this.

I have at least shown myself why the lavatube at 3.7 volts, is much more powerful than another 3.7 ecig.
It's the pulse width modulation, and technical people should understand.

 

[billherbst]

Fascinating, and encouraging. Nice work, Blitzer.

As a non-engineer, I can follow about 3/4 of what you wrote. That last quarter makes my head hurt. But I think I get the gist of what you're saying, namely, that the Vtube version 1.5t's implementation of PWM algorithms ends up mimicking Evolv's power-regulated chips, at least to some extent, and does so in an effective way that allows displayed voltages to provide a harder-hitting and more powerful vape than in unregulated VV devices, especially the Lavatube v1.0, to which it is clearly superior.

Though anecdotal, my personal experience with both the v1.5t Vtubes I own (a Vector Variable Volt from VaporBeast and a Varitube X from iVape) supports your data and suppositions. I've been so pleased with the performance of both units that I no longer care what the amp limit specs are. OK, so the early claims of 4.0 amps are clearly bogus, but I am also unconcerned about whether the amp limit might be the currently claimed 3.2, or 3.0, or even 2.88. It doesn't matter to me, since they vape like champs with every atty/carto or juice I throw at them.

Now I have an argument for why that is.

Thanks.

 

[hificat101]

Not really a scientific observation, but my 1.5 does indeed seem to be the best hitting device I have. It really seems to hit better than my Buzz Pro (sorry Mike) a fact that I really hate. It also hits slightly better than my 2x18650 Altoid mod. I'm not really sure how to describe it, short of simply saying it seems to provide a more enjoyable vape than my other devices. And to think I bought it as a temporary fill in device.

 

[1kshooter]

I follow....lts got lots of vape...tates great and has got me and my wife off smokes lol
I have smoked for 23 years and I now vepe and have not had one in 6-7 days? ya I don't even remember the last one!
I do find that i go through a lot more e-juice at higher volttage and that my wifes darker sweet chocolate stuf goes real dark quick on the Lava Tube and tastes burnt to her?!?
Jonathan

 

[Blitzer]

Here is a little analogy that demonstrates what I am talking about.

You have 2 cars going for a 10 mile drive. We will call these cars Ecig #1, and Ecig #2. (because we can...)

Ecig #1 goes 60 mph, and arrives in 10 minutes. (boring, not how we drive in Germany!)
Ecig #2 sits still for a minute, then drives 120 mph, then stops, then 120 again, etc...
Ecig #2 crosses the finish line at exactly the same time as Ecig #1.
The only difference is Ecig #2 has to try and explain to the Texas Highway Patrol that his AVERAGE speed was 60 mph.

That's what our lavatubes are doing. High voltages, on and off very quickly.

It's feels to the vaping person like it's really kicking...

I can treally feel the difference between a LT at 3.7 volts, and a regular ecig at 3.7 volts. Even at 3.2 volts, the LT
hits harder, and with more vapor.

Hope this makes more sense. I still have all the math, to prove it to anyone curious though.

 

[natgas]

While I don't follow much of what you've explained, I'm happy to hear that my LT's are doing what I thought they were!

Thanks

 

[HawkeyeCS]

Thanks for the info, I was hoping somebody would hook these up to a scope and post some results. Interesting how it locks in voltage at 9.5 watts... Little disappointed that I can't push this device past 9.5 watts, wasn't quite what I thought I signed up for when I bought it, but at the same time, I have been happy with the vape I've been getting, so not too disappointed I guess... Now gives me an excuse to buy a new device so I can push past 9.5 watts to see what that is like...

 

[unloaded]

Nice post. It confirms a few things I suspected. To keep cost down they seem to use a static boost to 6v rather than a variable. Also seem to be using PWM with a 50%-100% range rather than 0%-100%. Lastly my sweet spot seemed to be close to 10w based on ohm reading and selected voltage I always seemed to settle on. Your numbers confirm that I was probably getting a bit less in reality. This lets me know that the DNA with it's 12w limit should be fine for me. I'll be getting one of them shortly.

 

[Blitzer]

Ding Ding Ding Ding! Folks we have us a winner! Unloaded, you get it!

You can get numbers on a voltmeter that seem to tell a story on this device.
It's not a true story though, unless you are at the 6 v setting on the lavatube. (100 duty cycle- looks like DC)
From this max voltage, and understanding of PWM, and carto resistance- you can calculate everything
even without a scope. (Pk & avg power, true volts at any point on a graph, etc...)

I like you, and apparently HawkeyeCS (and others) like this device but would like a little more power.
I was under the impression this thing had a 12w max power limit, but I am nowhere near that.

I will "struggle" along with this Lavatube 1.5T until a new King of cheap VV devices makes itself apparent.
Then this will be a backup.

I have to say though, the engineers who designed this did a fantastic job for the price!

 

[unloaded]

Well, I'm liking the results I'm getting so my sweetspot must be less than 10w. Lets me know the 12w limit on the DNA will be plenty for me. If you're not familiar with it here is a thread and link to the site that carries them.

http://www.e-cigarette-forum.com/forum/battery-mods/297196-dna-modders-board-project.html

Our Products « Evolv
They have the datasheet on there too. For $35 you can build your own variable wattage mod with single battery!

 

[Blitzer]

Well, I'm liking the results I'm getting so my sweetspot must be less than 10w. Lets me know the 12w limit on the DNA will be plenty for me. If you're not familiar with it here is a thread and link to the site that carries them.

http://www.e-cigarette-forum.com/forum/battery-mods/297196-dna-modders-board-project.html

Our Products « Evolv
They have the datasheet on there too. For $35 you can build your own variable wattage mod with single battery!

Yeah, I am getting a good vape out of my Lavatube also. I just kept seeing these reviews
with people say "I wish I had a scope, so I could see what's REALLY going on...".
I have great test equipment, so why not have a look?

Wow, I am totally liking that DNA. I knew about the kick, but not the DNA.
I started out building all my own vaping devices, and only recently started picking up
pre-made devices. This DNA looks dead simple to wire up, I will probably get one too!

Thanks

 

[mnementh666]

Very nice. Pretty much exactly how I imagined it would play out. A little low on wattage, but that's ok. As you and others have said, I'm pretty satisfied with the vape itself, regardless of the "real vs measured" voltage.
My main question, should you feel up to it, is to find out how battery voltage affects (effects?) the measured peak voltage of the pulse.
In other words, if theLT is hitting 6v peak with 75%duty cycle for 4.5v reading, and that is on a fully charged 4.2v battery... What is the peak voltage and duty cycle on a low charge (3.5v) battery to hit the 4.5v reading. Or... Will the duty cycle remain the same but the peak voltage drop due to input voltage dropping.
I sincerely hope that made sense...

Sent from my HTC Vision using Tapatalk 2

 

[Blitzer]

Very nice. Pretty much exactly how I imagined it would play out. A little low on wattage, but that's ok. As you and others have said, I'm pretty satisfied with the vape itself, regardless of the "real vs measured" voltage.
My main question, should you feel up to it, is to find out how battery voltage affects (effects?) the measured peak voltage of the pulse.
In other words, if theLT is hitting 6v peak with 75%duty cycle for 4.5v reading, and that is on a fully charged 4.2v battery... What is the peak voltage and duty cycle on a low charge (3.5v) battery to hit the 4.5v reading. Or... Will the duty cycle remain the same but the peak voltage drop due to input voltage dropping.
I sincerely hope that made sense...

Sent from my HTC Vision using Tapatalk 2

Yeah, it makes sense. The duty cycle won't change. The peak voltage will remain
regulated all the way from full charge, until the battery can't provide enough current anymore.
Then the vape will get wimpy.

 

[thepiercefamily2001]

Wow. That's pretty good information. I just bought a lavatube. It is the version with the 2.5 amp limit. I am using 2.5 ohm single coil cartos in a 6ml tank. I followed all of what you said. I am very happy with the performance so far, but it is nice to see all of the technical info on it for those of us that are curious. So thank you for taking the time to do the research for those of us that were wondering about the electronic specifics of the device.

 

[billherbst]

Wow. That's pretty good information. I just bought a lavatube. It is the version with the 2.5 amp limit. I am using 2.5 ohm single coil cartos in a 6ml tank. I followed all of what you said. I am very happy with the performance so far, but it is nice to see all of the technical info on it for those of us that are curious. So thank you for taking the time to do the research for those of us that were wondering about the electronic specifics of the device.

pierce,

Someone will correct me if I'm wrong, but I think what Blitzer tested and theorized about is the Young June v1.5t Vtube, not the L-Rider original v1.0 Lavatube, which is what you have (with the 2.5 amp limit). The L-Rider device does not have PWM (pulse width modulation).

 

[Blitzer]

pierce,

Someone will correct me if I'm wrong, but I think what Blitzer tested and theorized about is the Young June v1.5t Vtube, not the L-Rider original v1.0 Lavatube, which is what you have (with the 2.5 amp limit). The L-Rider device does not have PWM (pulse width modulation).

You are correct about me testing the newer version 1.5T. The original version was not Pulse width modulated
like the new one is. There are some graphs on the vapors alley site that show the difference. The original flattens out
the voltage at the top end. The new version is REALLY linear due to the PWM. Whatever voltage you get at the 6 volt setting, divide this in half to get the voltage at the 3 volt setting.

I might still pick up a mini of the older version, if I can find a sweet sale after all the newest ones start becoming available.
I think it gives plenty good performance for a pocket friendly VV device. I have a bunch of old dual coil cartos, that I have been snipping the top wire to make single coil cartos. Should work great on the v1 lavatube.

 

[Blitzer]

Wow. That's pretty good information. I just bought a lavatube. It is the version with the 2.5 amp limit. I am using 2.5 ohm single coil cartos in a 6ml tank. I followed all of what you said. I am very happy with the performance so far, but it is nice to see all of the technical info on it for those of us that are curious. So thank you for taking the time to do the research for those of us that were wondering about the electronic specifics of the device.

Thanks for the kind words. I was wondering if I went too technical there for a while!

 

[billherbst]

My only small gripe about the mini is the fire-button placement. The regular-size 18650 Vtube is 123mm in length. The 18350 mini cuts 28mm off the bottom of the tube, which shifts the fire-button closer to the middle. I understand that a re-design of the placement of the guts is not cost-efficient (since it's a no-brainer to just cut down the battery tube), but I wish the fire-button were located higher, where it would be a more ergonomically natural placement for the thumb. Not a major criticism, though. The mini is certainly more pocket-friendly.

The v1.5t minis are starting to show up, but they're priced the same as the 18650-length. V1.0 minis should hit the bargain bins real soon. I guess the eGo-C Twist 650mAh is another option, but I'm not in love with the 2+ hours of usb recharging. More convenient to simply carry a spare 18350 in your pocket with the LT mini (and a better vape as well).

Speaking of ergonomics, what I most love about the Young June Vtubes---v1.5 (rest in peace), v1.5t, and the soon-to-arrive chrome v2.0 with the 4.0 amp limit (supposedly) and the spiffy spring-loaded positive pole on an eGo-style 510 connector top---is the efficient implementation of resistance checking, current set voltage, and battery-remaining graph, all of which are accessed by a single click of the power button. That's so much better than the ProVari and SmokTech Vmax menu systems, at least to my way of thinking. No morse code multi-click-and-wait techniques required. In fact, no thinking required. Just one click and there's all the info. Brilliant. Just one more reason I didn't buy an L-Rider v1.0, which has no resistance checking (a feature I'd prefer not to live without).