VAMO V2: the Problem with the Effectiveness of the Device

[awsum140]

Awesome write up on the response and thanks for taking the time to do that.

My initial comments on the drop from 4.1v to 3.7v nominal are based on charts like these: 18650 battery test 2011. So, the drop to nominal is sort of relative based on the rate of change in the slope compared to 3.6/3.7v and the more pronounced drop at 3.3/3.4v.

However, the result of your tests makes me think of something that I had not considered. Most of the battery tests are done at continuous discharge. vaping is done in pulses and may show a marked difference in the discharge slope as compared to other applications.

If you click this link and read through to page 61 or so, you'll see the results of both "real world" current and load testing using a Vamo and a computer controlled battery tester. Both an 18650 and a stack of 18350s were tested.

http://www.e-cigarette-forum.com/forum/vamo/355592-vamo-battery-thread-57.html

 

[cckk]

awsum140,

In post #569 from the mentioned above thread you refer to http://leosedf.blogspot.com/. In that blog entry from July 14, 2013 the author reports the results of the tests of two configurations:

So we created a "vape" simulation with both batteries, it draws the same power that the Vamo uses during vaping for 5 seconds and rests for 25 seconds. All that to simulate the actions of the user while using it. It's like chain vaping until the battery reaches the 3.3 cut off voltage. (we didn't use the 2.750V cut off since users tend to recharge the batteries at 3.3V)

The 18650 gave us 250 puffs both times. Continuous vaping for 2 hours

The stacked 18350 gave us 477 puffs (?!?) the first time and 479 the second time. Continuous vaping for 4 hours

Seems like using two stacked batteries performs a lot better.

Get the files here:
https://docs.google.com/file/d/0BxL-fHC-i2cBUzcwQk5va21ZMVU/edit?pli=1
https://docs.google.com/file/d/0BxL-fHC-i2cBSE5zaV9NR2gyYzQ/edit?pli=1


Note: the stacked 18350 batteries ran cooler than the 18650 mainly because the mod draws 1.02A at 7W so there was not so much stressing.

In the note author reveals that two stacked 18350 batteries drew 1 A at 7 W. That means that the device worked with the voltage 7 V and the resistance 7 Ω.

You took the part in those tests. Could you reveal the configuration of the device using one 18650 battery used in those tests? I mean: the amperage, the power, the voltage, and the resistance.

 

[cckk]

Could you reveal as well the capacities of the tested 18350 and 18650 batteries?

 

[awsum140]

I really didn't take part in the tests, they were done in Greece and I'm in the US. I just cajoled and nagged Tritium to do them as an intellectual exercise.

The batteries tested were all Efest with the 18650 being a 2000mah and the 18350s being 800mah.

The device was a commercial battery testing system that is programmable through an attached PC. I don't remember the actual name and model of the device, but it a real, commercial, test gear costing just under a thousand dollars. He has also tested number of other batteries with standard load testing, IE continuous load/recharge/load/recharge. Tritium is an electronics technician and routinely works on UPS systems from1.5kva all the way up to hundreds of kva and is very familiar with battery chemistry, capacity and reliability.

 

[cckk]

awsum140,


I assumed that you took the part in these tests because the author of the blog wrote:

I have some Efest batteries from the last test and awsum140 measured some current consumptions for me.

I wondered whether vaping at 7 Ω produces any noticeable vapor. Now I know that these tests were performed by some programmable system. I’m afraid that it was an experiment which hasn’t nothing in common with the real vaping. The result are awesome at 1 A but try to make 7 Ω coil and I’m pretty sure you can’t notice any vapor.

***

By the way: you use notoriously the wrong math.

Here: http://www.e-cigarette-forum.com/fo...roblem-effectiveness-device.html#post10191869 you changed the Ohm’s law to I=W/R.

Here: http://www.e-cigarette-forum.com/forum/vamo/355592-vamo-battery-thread-58.html#post10043427 you changed the Ohm’s law to P=IE.

The above equations work when I = 1 A. In the other cases they don’t work.

Here are the right equations:

I = V / R or I = P / V, or I² = P / R

R = V² / P or R = V / I, or R = P / I²

V = I × R or V = P / I, or V² = P × R

P = V² / R or P = I × V, or P = I² × R

 

[awsum140]

You cite, in the power line, that P=IxV. I assume that I represents current and V represents voltage. When I used P=IE the I represents current and E represents voltage. How that is notoriously in error or is factually different from what you posted, I am at a loss to explain. Remember that the Vamo is using a buck/boost circuit to control power and those reading were taken in the so called RMS mode directly off the battery. The square wave being generated by the Vamo and supplied to the atomizer was not monitored, but it would be safe to assume that the voltage was significantly higher and the pulse width was controlled by the Vamo to achieve the 7 watts.

I did take part in the tests in that I took the current readings directly off two different Vamo devices that I have. I checked at both 7 watts and at 10 watts as the posts indicate. The current readings were taken using a generic multimeter that I have and it is certainly not traceable to any NBS reference but seems to be accurate enough for vaping use. The load testing was done by Tritium who is in Greece based on those current readings, specifically the 7 watt level since that is close to where most, but certainly not all, vapers seem to vape at especially if using commercially produced delivery devices. The 10 watt current readings were taken by me to see what happened at higher output levels and did show a degradation in efficiency probably caused by losses in the buck/boost circuit.

In terms of the test itself, it does represent a better model to actual vaping than a continuous high current, say 1C or higher, load that normal battery specifications show. The cyclic nature of the test, by itself, would seem to be closer to "real world" than a continuous load. The fact that accurate and constant readings of battery load and voltage levels more accurately describes what happens to a battery under normal vaping conditions which are an intermittent load, at least I feel it does.

 

[cckk]

awsum140,

You use some non-standard symbols in your equations. Assuming that W in your first equation is for voltage and E in the other equation is for voltage as well both your equations are right. But that doesn’t change the fact that the currents which you calculated here: http://www.e-cigarette-forum.com/fo...roblem-effectiveness-device.html#post10191869 are wrong:

Using Ohms Law, I=W/R, an 1.8 ohm coil requires about 5.5 amps to produce 10 watts, while a 2.6 ohm coil requires about 3.8 amps.

In fact an 1.8 Ω coil requires about 2.36 A to produce 10 W, while a 2.6 Ω coil requires about 1.96 A to produce 10 W.

On the other hand here: http://www.e-cigarette-forum.com/fo...roblem-effectiveness-device.html#post10192782 you made the other mistake:

At 6 watts a 2.6 ohm coil will draw about .95 amps.

In fact at 6 W a 2.6 Ω coil draws about 1.52 A.

In the first case your results for the current are too high and in the other case it’s too low. That’s the reason for which I stated that your math is notoriously wrong.

***

I’m still in doubt that vaping at 7 Ω produces some noticeable vapor.

 

[awsum140]

The letter "E" is a classic way to reference voltage or electromotive force.

The rest is what happens when you forget to take the root.

Again, the 7 ohm assumption does not include the fact that the Vamo uses a boost circuit, square wave and pulse time management to produce the 7 watts at one amp. Also, keep in mind that measurement was on a stack of two 18350s which was producing 7 volts.

 

[sailense]

Constants -
Stacked voltage - 8.3 volts
Atomizer resistance 2.7 ohms
Calculated current at 7 watts - ~.84 amps
Calculated current at 10 watts - ~1.2 amps

Stack at 7 watts - 1.02 amps
Stack at 10 watts - 1.53 amps

18650/2000 at 10 watts - 3.76 amps
Calculated current at 10 watts(3.8 volt supplied) - ~2.63 amps

I was looking over that thread and I'm curious to know how you calculated the amp draw.

If we have:
Resistance: 2.7Ω
Target Power: 7W

Then, we find the voltage needed, assuming you're using the power setting on the Vamo:
P=V^2/R
V^2=P*R
V^2=7W * 2.7Ω
V^2=18.9
V=sqrt(18.9) = 4.35V approx.

Then from that:
E=IR
4.35V = I * 2.7Ω
I = 4.35/2.7
I = 1.61A

I'm pretty sure that was calculated correctly, but there may have been something I missed.

 

[awsum140]

The calculated results are a result of P=IE(or V) or I=P/E. 8.3 times .84 equals 6.972 watts, rounding numbers gave the .84 amps. The same is true of the 10 watt reading, 8.3 times 1.2 equals 9.86 watts. Those calculations were made to determine what the "pure" current load would be with no electronics involved. The actual measurements were made to determine what the "real life" current consumption was by the device when operated at those levels and allow an idea of what the current, or power, "overhead" is to achieve those power levels.

 

[cckk]

Glen Snyder,

As I reported in the first post my style of vaping is the following:

1. I put fully charged 18650 3400 mAh battery into a device.

2. I fill the entire 3 ml tank with a liquid.

3. My goal is to vape the entire tank using one battery without discharging it too much.

After stabilizing the battery used in VAMO I performed the tests announced in the post #14.

The Batteries

I own three batteries: “A”, “B”, and “C” – all of them are 18650 3400 mAh made by Panasonic and marked as NCR18650B Li-ion MH12210. Here’s the report about the state of my batteries after the mentioned above stabilization but before the tests:

● “A” – this is the battery which I used so far exclusively with The Natural and RSST. During vaping the entire 3 ml tank it discharges to 3.6 V and then charges back to 4.2 V. When it was brand new it discharged to 3.7 V – the same as the other batteries.

● “B” – this is the battery which I used a few times with VAMO V2 and AGA-T2 as I reported that in the first post. That battery used now with The Natural and RSST discharges to 2.7 V and then charges back to 4.0 V. So VAMO discharging that battery a few times to 3.2 V and using the pulsing mentioned by sailense worsened it significantly.

● “C” – this is the battery which I discharged once to 2.7 V using it with The Natural and RSST to vape two 3 ml tanks. I use it now with The Natural and RSST for the comparison purposes. During vaping the entire 3 ml tank it discharges to 3.4 V and then charges back to 4.2 V. So discharging that battery once to 2.7 V worsened it a bit though it’s still better now than the battery used a few times with VAMO.

Because VAMO worsens the batteries significantly I decided to perform just one half of the promised test. So I tested The Natural with AGA-T2 but I refrained from testing VAMO with RSST because I don’t want to worsen the next battery.

First Test (Battery “A”)

In my first test I used The Natural and AGA-T2 with the battery “A”. During vaping the entire 3 ml tank the device discharged the battery to 3.7 V and then it was possible to charge it back to 4.2 V.

The slightly better result achieved with The Natural and AGA-T2 (discharging the battery “A” to 3.7 V) than the results achieved by The Natural and RSST (discharging the same battery to 3.6 V) is caused in my opinion by different wicks used in both cases. With RSST I use 20 mm wide wick but with AGA-T2 I use 25 mm wide wicks. Slightly more massive wick used with AGA-T2 results in better providing of the liquid. That shortens the total time of the vaping of the entire 3 ml tank causing slightly lower discharging of the battery.

Second Test (Battery “B”)

In my second test I used The Natural and AGA-T2 with the battery “B”. During vaping the entire 3 ml tank the device discharged the battery to 3.4 V and then it was possible to charge it back to 4.1 V.

I reported above that after the stabilization The Natural with RSST discharged that battery to 2.7 V and then it was possible to charge it back to 4.0 V. I was wrong assuming that I stabilized that battery because the present test shows that it still stabilizes.

The Conclusion and the Doubt

The most important conclusion for me is that I can vape the entire 3 ml tank using The Natural and just one battery but using VAMO I should change the battery in the middle of the 3 ml tank in order to not discharge the batteries too much.

My biggest doubt now is whether VAMO worsens the batteries only when they are discharged to 3.2 V or it worsens the batteries all the time pulsing the voltage of the battery as sailense explained that. Because the battery “C” which I discharged once to 2.7 V behaves better than the battery “B” discharged for a few times with VAMO to 3.2 V it seems to me that VAMO exploits the batteries using the mentioned pulsing of the voltage. So VAMO isn’t too friendly for the batteries even when one doesn’t discharge them to 3.2 V.

Nightly Shopping

After one week of the deliberations I decided the last night to buy the next multimeter. My first one – which died after two weeks of the usage – was Düwi 07980 (as I remember it cost about 15 USD). Now I bought YATO YT-73087 (it costs about 90 USD). YATO is much better than Düwi. Among the other things it allows to measure the temperature. That may be a convenient method of the comparison of different coil and wick setups. I’m still waiting for my new multimeter.

 

[cckk]

sailense,

In your post #4 you explained that VAMO pulses the voltage of the device to 6 V in order to count the valid voltage settings for the given resistance.

I see three possibilities:

1. VAMO pulses the voltage at a given frequency (for example once a minute).

2. VAMO does that when user checks any value, changes it, or fires the device.

3. VAMO does that just when user fires the device.

You wrote that VAMO does that at a certain frequency (variant 1.). Are you sure that it does that that way or you just guess? If you’re sure did you found such an information somewhere? If you found it could you post a link?

It’s possible to test that but it requires three tests and I’d like to avoid them because VAMO worsens my batteries as I described that above in my reply to Glen Snyder.

 

[awsum140]

If you haven't seen this video, which is kind of long, at around 16 minutes in he starts talking about the pulse modulation and includes scope traces of the output of the Vamo - A PBusardo Review - The Vamo - YouTube

The Vamo is similar to many of the other "popular" VV/VW devices and probably uses the same or very similar chipset to handle power management. They all seem to run at about 33 cycle pulses of varying widths to control power by producing a square pulse. You may also want to check lithium battery info on BatteryUnversity. There's a good amount of interesting information about lithium batteries in general as well as on specific types of lithium batteries.

 

[Blix]

Great thread and shows how consitent a vape you really get with a mech mod, many seems to be under the impression that the voltage drop is heavy.
My main work vape is a Reo Grand, and I use Panasonic NCR18650PD batteries, on a 7.5 hour work day my battery is usually around 3.9 volts when I come home, and the drop from 4.2 volts isn't very noticeable.
Same with my Silver Dog hybrid. Both have atties with 1.0 ohm coils.

Quite good I'd say.

 

[cckk]

awsum140,

I watched that Phil Busardo video twice before I bought VAMO V2 but I overlooked the information about the pulsing at a given frequency because I was interested then just in the overall VAMO features.

As for Battery University I read some information about the batteries there during the last few weeks but now I’m interested in the specific information concerning battery usage by the mechanical and electronically controlled MODs. The only method to get them is to perform some tests so I do that.

Blix,

Thank you for the positive feedback.

As for my first device I bought The Natural with RSST. Because I was very glad of them I wanted to buy as a backup... The Natural with RSST. But later I decided to buy an electronically controlled MOD with some other popular atomizer in order to compare these two types of MODs. As I reported in my reply to Glen Snyder from post #14 I don’t like VAMO V2 and AGA-T2 too much. VAMO drains the batteries too fast and shortens their life and AGA-T2 uses tiny coils and wick which are difficult in the preparation and maintenance.

Glen Snyder,

Fifteen minutes after I wrote my reply to you from post #31 a courier delivered my new multimeter. I can’t measure with it the temperature of the wick because the probe of the thermoelement is too thick to put it inside the wick. Maybe there are some thermoelements for the multimeter with needle probes on the market – I should check that. I don’t worry too much because I can measure with my new device the temperature in my room as well as the humidity, the noise level, and the light intensity. None of these values has something in common with the vaping but all of them have a lot in common with a fun.

I put the receipt into the multimeter case in order to know where it is – just in case. Now I may even forget where I put that receipt because I put a hint for me in that thread. Of course I may forget also where I put the multimeter case. It isn’t possible to protect oneself entirely against forgetfulness.

***

I just finished to vape 3 ml tank using The Natural and AGA-T2 with the battery “C” (the one which I discharged once to 2.7 V). During that test my device discharged that battery to 3.6 V while The Natural with RSST using slightly thinner wick discharges it to 3.4 V.

After comparing 20 mm wide and 25 mm wide wicks I decided to switch to more massive ones. The 20 mm wick is the thinnest usable wick. Slightly thicker wick offers small safety margin and saves the batteries better though it consumes more liquid.

 

[cckk]

After considering what sailense wrote about electronically controlled MODs which pulse the voltage at a given frequency to count the required power I devised a consecutive test.

So far I used VAMO V2 in the recommended mode No. 2 (RMS) and I preset the wattage (6.0 W at 1.6 Ω). VAMO used that way discharged the 18650 3400 mAh battery to 3.2 V allowing to vape about 7/8 of the entire 3 ml tank of AGA-T2. After using that battery in VAMO a few times I put it into The Natural. At the beginning The Natural discharged it to 2.7 V (though earlier it discharged it to 3.6 V) and my charger was able to charge it to merely 4.0 V (though earlier it charged it to 4.2 V). After a few full and short cycles in The Natural that battery regained finally their original voltage – 4.2 V.

At that point I invented a perfidious test. I switched VAMO to mode No. 1 (AVG) and instead of preset the wattage I preset the voltage. In the previous round I used that battery with 1.6 Ω coil and 6.0 W. Now I used it still with 1.6 Ω coil and I set the voltage to 3.1 V in order to get 6.0 W as in the first round.

Surprise! I vaped 3 ml of a liquid twice using AGA-T2 atomizer in the mentioned configuration using that battery two times. For the first time the vaping of the entire 3 ml tank lasted for 8.5 hours, the initial voltage was equal 4.2 V and the final voltage was equal 3.4 V. My charger was able to charge that battery to 4.0 V. For the seconds time the vaping of the entire 3 ml tank lasted also for 8.5 hours, the initial voltage was equal 4.0 V and the final voltage was equal 3.4 V.

So – according to my speculations – VAMO V2 in the mode No. 1 (AVG) with the preset voltage doesn’t have to count the voltage (because it’s preset) so it doesn’t perform all those stupid actions which it does in mode No. 2 (RMS) to count the voltage and which – as a side effect – worsen the battery and doesn’t allow to vape the entire 3 ml tank.

This is the message to the users of the mechanical MODs:

Hi guys and gals! You may use VAMO – and the similar MODs – almost the same way as you use your mechanical MODs. Just switch VAMO to mode No. 1 and preset the voltage instead of the wattage.

Here’s my vague chart (two sessions with VAMO V2 in AVG mode with the preset voltage using my battery “B”):

 

[cckk]

Side note: I frequently observe that doing something in the opposite way than the majority does works better for me.

 

[dr g]

nevermind...

 

[cckk]

I published the report about the next batch of the tests here: http://www.e-cigarette-forum.com/fo...all-about-wire-temp-read-14.html#post10305930. I’m sorry for that inconvenience but most of the information in the mentioned post is related to that other thread. The policies of the most forums forbid to post the same content in two threads. I don’t know whether ECF policy forbids that but if it doesn’t it should.

Here I publish the graph of the results of vaping the entire AGA-T2 3 ml tank using VAMO V2 in No. 1 mode and the voltage preset to get 6 W. I did that twice with two different resistances. As you see the battery voltage drops practically in a linear way – from 4.0 V to 3.4 V.

I did these tests before the tests described in the post mentioned above. To get 6 W at 1.6 Ω I set VAMO to 3.1 V and to get 6 W at 2.0 Ω I set VAMO to 3.5 V. Meanwhile because of the voltage drops described in the mentioned above post the real voltage in the first case was 3.05 V and in the other case 3.36 V so the real wattages were 5.8 W in the first case and 5.6 W in the other one.



dr g,

Maybe you shouldn’t delete your original post because your original comment could be very funny.

 

[MikeE3]

I published the report about the next batch of the tests here: http://www.e-cigarette-forum.com/fo...all-about-wire-temp-read-14.html#post10305930. I’m sorry for that inconvenience but most of the information in the mentioned post is related the that other thread. The policies of the most forums forbid to post the same content in two threads. I don’t know whether ECF policy forbids that but if it doesn’t it should.

Here I publish the graph of the results of vaping the entire AGA-T2 3 ml tank using VAMO V2 in No. 1 mode and the voltage preset to get 6 W. I did that twice with two different resistances. As you see the battery voltage drops practically in a linear way – from 4.0 V to 3.4 V.

I did these tests before the tests described in the post mentioned above. To get 6 W at 1.6 Ω I set VAMO to 3.1 V and to get 6 W at 2.0 Ω I set VAMO to 3.5 V. Meanwhile because of the voltage drops described in the mentioned above post the real voltage in the first case was 3.05 V and in the other case 3.36 V so the real wattages were 5.8 W in the first case and 5.6 W in the other one.

View attachment 238885

dr g,

Maybe you shouldn’t delete your original post because your original comment could be very funny.

I looked at your test results in the 'other thread' - you attention to detail is amazing. When doing those tests is there a reason you used Mode 1- avg, when testing voltage and Mod 2 - rms, when testing wattage? Makes me wonder a.) Would the set/measured values be better/worse when setting the voltage and using Mode 2-rms? And b.) would the set/measured values for wattage be more consistent in Mode 1 avg?