VAMO V2: the Problem with the Effectiveness of the Device

[cckk]

Smoktech The Natural with Smoktech RSST

I use as my main device Smoktech The Natural MOD with Smoktech RSST atomizer. My coils have on average 1.6 Ω. The tolerance of my hand made coils is ±0.1 Ω so I stay with my coils in the range from 1.5 to 1.7 Ω. I use 18650 batteries with 3400 mAh capacity.

With the above setup while I vape the entire 3 ml tank of a liquid the battery voltage drops from 4.2 to 3.6 V – on average it’s 3.9 V. Assuming that my coil has 1.6 Ω the power during vaping the entire tank drops from 11 to 8 W and the average power is 9.5 W. After recharging the battery drained to 3.6 V it charges back up to 4.2 V.

VAMO V2 SS with AGA-T2

For the testing purposes I bought VAMO V2 SS MOD and AGA-T2 atomizer. My coils for AGA-T2 have on average 1.6 Ω so they are similar to my coils for RSST.

At the beginning I assumed that vaping 3 ml of the liquid with VAMO V2 and AGA-T2 using 9.5 W power – the same as the average power used with The Natural and RSST – should drain the battery the same way: from 4.2 V to 3.6 V. So I started to vape the first 3 ml tank using 9.5 W power but I realized quickly that VAMO drains the battery faster than The Natural so I switched the device to 8.5 W, then to 7.5 W, and I finished vaping that first 3 ml tank using 6.0 W. Despite of that the battery reached at the end 3.3 V.

So for the next time I started with 6.0 W using 1.5 Ω coil. In such a case the used voltage is equal 3.0 V. I assumed that using the lower wattage and lower voltage should drain my battery less. In spite of that the battery reached 3.2 V near the end of the tank and VAMO refused to work because of too low voltage. So I wasn’t able to vape the entire 3 ml tank using my 3400 mAh battery.

I tried the same setup for the next time and the result was the same.

Moreover the batteries drained with VAMO V2 to 3.2 V charge back to 3.9 V instead of 4.2 V.

The Problems and the Question

● VAMO V2 used with 6.0 W is less effective than The Natural used with the power dropping from 11 to 8 W (9.5 W on average) because it doesn’t allow to vape the entire 3 ml tank.

● VAMO V2 is more demanding because it drains the battery to 3.2 V while The Natural drains them to 3.6 V during vaping the entire 3 ml tank.

● The battery drained with VAMO V2 to 3.2 V charges back to merely 3.9 V while the battery drained with The Natural to 3.6 V charges back to 4.2 V.

My question is: why VAMO V2 used with 6.0 W and 1.5 Ω resistance (draining the battery at 3.0 V) is less effective than The Natural draining the battery from 4.2 to 3.6 V with 1.6 Ω resistance (using from 11 to 8 W)?

 

[TFL!]

Was the vamo set to No1 or No2?

 

[cckk]

My VAMO works in No. 2 or RMS mode.

 

[sailense]

This is most likely due to the booster used in the Vamo and the additional power needed for the circuitry.

In the mech, you're getting direct voltage from the battery starting at 4.1-4.2v, quickly draining to 3.7/3.6v, and staying there for most of the charge since that's the nominal voltage.

In the Vamo, it uses pulse width modulation to pulse 6v at a certain frequency in order to match the set voltage or wattage. So, even if you set it for 3v, it still pulses at 6v, albeit for a shorter duration, and you will get less battery life than a straight mech mod.

This is true for all mods that use PWM. I believe the Provari actually modifies the output charge so that may compare better with the battery life of your mech.

 

[dmanindfw]

May be a bit off subject and battery experts may want to weigh in on this thread. Sounds like your battery is a ICR protected or non protected Li-Ion. Or is it a IMR? I am guessing ICR due to the high mAh rating you posted.

Personally I don't drain my ICR batts below 3.7V but generally you can go down to 3.4-3.5 without affecting the overall battery life (i.e. how many times you can cycle your battery). As you let your battery drop to 3.2V and then said it only charged back up to 3.9V I'm wondering if your charger doesn't have a timer built in to keep from overcharging your battery. For example, your charger may have a timer that limits charge time to 5 hours and then cuts off. If you have a battery at 3.5V and it charges until full at 4.2V all is fine as it fully charges within 5 hour (safety) timer. But if you start at 3.2V and at 5 hours it hasn't fully charged to 4.2V, it's possible that your charger has some logic built in that terminates charging at 5 hours as a safety precaution to overcharging or overheating. Just a thought but it didn't make much sense that while charging your battery, your charger terminated at 3.9V.

BTW, I have a Pila charger, recognized as one of the safest and best and it 100% of the time terminates at 4.12V with my AW ICR batts. That's a bit lower than 4.2 that many chargers terminate at but I am completely fine with that as it will probably give me a few more cycles out of my batteries over the long run.

 

[awsum140]

Just a guess, but I would say that the Vamo requires more current to operate its buck/boost circuit and square wave generator. I am not familiar with the Smoktech Natural, but from what I can see it is a "passive" or mechanical mod, IE no internal electronics to provide variable voltage and/or variable wattage. Those circuits do consume power, on their own, simply to operate. Once you get internal electronics involved battery life will be shortened when compared to a "mechanical" mod.

I have measured current drawn by a Vamo using a nominal 2.6 ohm coil and operated at seven and ten watts. At no time di the current draw exceed four amps and was generally around 3.5 amps. The results using a stack of 18350s versus a single 18650 showed a significant increase in efficiency and a current draw drop of more than half. The current readings stayed under 1.5 amps for both seven and ten watts.

Bottom line is that adding electronics adds current draw that is not available to the atomizer which, in turn, shortens useable charge time.

 

[cckk]

sailense,

Thank you for that explanation.

When I bought VAMO V2 I used it to test Smoktech The Natural. So I put fully charged battery in The Natural and filled the entire 3 ml RSST tank with a liquid. Than I used The Natural and RSST to vape the liquid. Every 15 min. I removed the battery from The Natural and I put in into VAMO just in order to test the voltage.

The following chart shows the results. I vaped the liquid to the last drop for 6.25 hours (6 hours 15 minutes). The device started from 4.2 V and ended on 3.7 V. In my first post I reported that The Natural wears the battery out from 4.2 to 3.6 V but it concerns the present results. When my battery was fresh The Natural wore it out from 4.2 to 3.7 V as I show that on the chart.

As you can see The Natural wears the battery out almost in a linear way. The longest period is when the battery has 3.9 V. So you’re wrong when you assume that the device drains the battery quickly to 3.7–3.6 V and then stays in that nominal voltage for most of the time. It doesn’t work that way at least in the case of the mechanical MOD such as The Natural.



dmanindfw,

I use the unprotected batteries by Panasonic NCR18650B 3400 mAh (see: Test of Panasonic NCR18650B 3400mAh (Green)) together with Efest LUC charger (see: http://www.e-cigarette-forum.com/forum/vaporalley/419830-added-efest-luc-smart-chargers.html).

As for that charger it hasn’t the timer. I performed an exhausting test on one such a battery. I charged it to 4.2 V and then used it to vape the entire 3 ml tank using The Natural. As a result the battery voltage dropped to 3.7 V. Then I filled the tank anew and used the same battery to vape the next tank. I managed to vape the other entire 3 ml tank using the same battery. As a result the battery voltage dropped to 2.7 V.

Then I charged that battery. My charger was able to charge it to 3.8 V.

Next I used the same battery with The Natural to vape just one 3 ml tank. As a result the battery voltage dropped to 3.2 V.

Finally I recharged that battery anew. The charger was able to charge it to 4.2 V.

So it seems that the charger is able to charge the battery to 4.2 V when it isn’t discharged too much. Even the battery discharged to 2.7 V can be recharged to 4.2 V two cycles later.

Of course discharging the battery to 2.7 V isn’t too smart. I did it just once to test the battery and the charger. I marked my batteries with the letters so I know which battery was exploited too much and I observe its behavior. So far it behaves stable: similar to the other batteries.

As for the general rules I try to use one 3400 mAh battery to vape the entire 3 ml tank. In the case of The Natural 3400 mAh battery is enough to vape 3 ml of a liquid and the battery voltage drops to 3.7–3.6 V. In the case of VAMO V2 one 3400 mAh battery isn’t enough to vape 3 ml of a liquid (it allows to vape about 7/8 out of 3 ml leaving 1/8 of a liquid in the tank) and as a result VAMO drains the battery to 3.2 V.

awsum140,

Your 2.6 Ω coil used with 7.0 or 11.0 W is much more demanding for the device than my 1.5 Ω coil used with 6.0 W. You use two stacked 18350 batteries and I use single 18650 3400 mAh battery. Your goal is to boost the voltage. My goal is to use the amperage to vape the entire 3 ml tank.

Your explanation of my case is similar to the explanation by sailense.

 

[awsum140]

I do have to point out that that I tested using both 18650 single mode and 18350 stacked mode. The single 18650 drew far more current to produce the same power as the stacked 18350s since the operating voltage is lower for a single battery. 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. None of those numbers account for the overhead of the device being used, but do show a higher resistance coil is less demanding in terms of current.

 

[cckk]

I² = P / R

Your case: P = 10 W with R = 2.6 Ω uses I = 1.96 A.

My case: P = 6 W with R = 1.5 Ω uses I = 2 A.

So in both cases the current is roughly the same.

 

[awsum140]

But with a 40% lower power output with a 1.5 ohm load. At 6 watts a 2.6 ohm coil will draw about .95 amps.

 

[cckk]

I tried both The Natural and VAMO with similar resistances assuming that the results should be similar as well. As it turned out VAMO performs some additional operations which drain the battery much more than with The Natural.

I could increase the resistance using VAMO as you suggest. That lowers the demanding for the current but that increases the demanding for the voltage at the same time. So the final result may be exactly the same assuming that I still use one 18650 battery – the battery drained to 3.2 V and not all 3 ml tank vaped out.

 

[Glen Snyder]

Just an observation...your experiment is flawed by using different delivery devices even though they well may be similar resistance. There's more in play in the vaporizing of e juice than power alone. You would have a more accurate finding if you used the same delivery device on both APV's. Even more accuracy if you continued with the second delivery device on both APV's. If you did that and I missed it after reading the OP 3 times then poop on me


Edit: More accuracy using a decent dmm instead of the Vamo to measure remaining battery charge too.

 

[awsum140]

To really simplify things, just check the current draw on the Vamo and the Natural. I think you'll be surprised at the difference with the Vamo being considerably higher.

 

[cckk]

Glen Snyder,

I doubt that the situation which I described in the first post is caused by the atomizer but I can of course switch my atomizers and test AGA-T2 on The Natural and RSST on VAMO V2. I’ll do that soon but first I have to stabilize my batteries after using them in VAMO.

My enthusiasm concerning the tests of different devices isn’t so immense to encourage me to buy another AGA-T2 in order to test the same atomizer on both MODs at the same time. I don’t like AGA-T2 and VAMO V2 too much. I bought both just in order to test an electronically controlled MOD and compare it to the mechanical one.

As for a digital multimeter my died after two weeks of the usage. I have no idea where I put a receipt so I can’t give that multimeter back to the hardware store. I’m not eager to buy the same multimeter in the same store once again because I’m afraid that it can die after two weeks. As for the other stores and multimeters I didn’t ponder about them too intensively so far.

awsum140,

As I understand my first post I reported in it that the current draw by VAMO is considerably higher than by The Natural. So either I don’t understand your advice or you advise me to do something what I did before I started that thread.

 

[awsum140]

Sorry, I didn't see that you had checked the current draw on both.

 

[cckk]

No problem. I always try to describe the problem thoroughly but as a result my posts become overcomplicated.

 

[awsum140]

I know that feeling!

 

[sailense]

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.

 

[cckk]

sailense,

Thanks a lot for your thanks.

***

Nice charts.

It’s 6:42 AM here and I just finished watching “La Vie en Rose” with the astonishing performance by Marion Cotillard. Now I’m listening Edith Piaf and am preparing a coffee. Then I’ll see through these charts. So thanks for the charts as well.

 

[cckk]

sailense,

I just finished watching these charts. In the case of a low current such as 0.2 A the graph is such as you described it in your first post but in the case of a medium current such as 2 A the graph is almost linear most of the time. The currents used with the MODs are the medium ones. For example my MODs – The Natural and VAMO – used with the coils 1.4–1.8 Ω use the current 2–3 A.