VV eGo vs eGo Booster vs Riva Batteries

[JW50]

Using data derived from this chart:


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And data developed by vocr and posted here: http://www.e-cigarette-forum.com/for...ed-review.html

And data developed by pmos69 and posted here: 3-Stage Variable eGo with LED screen & Super kits Exclusive to GV 3 Stage Variable EGO(2 batts),Cone,5 TC Clearomizers IN STOCK NOW!!

And data shown here for the eGo Booster: Artisan's Workshop - Ego Booster.m4v - YouTube

And using data individually obtained, the following chart was constructed:


What the constructed chart basically indicates is that the VV (variable voltage) eGo (also called a "639") is a device that operates in three distinct voltage ranges with its high range being basically identical to the EM Riva. However, because the VVs cut-off voltage is higher than both the Riva and the Joye eGo it will have a shorter usage period than either the Riva or the Joye eGo except when the device is used exclusively in the low range. The higher cut-off, lower number of uses is not necessarily bad as what is being lost is lower power vapes. Interestingly, the eGo Booster, operated at high throughout a discharge cycle, reduces discharge life by only about 10% as compared to an eGo with no Booster.

It is perhaps interesting to note that a Riva just off the charger (hit "1") has a loaded voltage very close to that of the eGo Booster (about 3.9 vs 4.0). The voltages shown in the chart are RMS voltages - or at least that is what intended. The Riva battery is the only device shown in the chart that is not pulse width modulated (PWM) or affected by PWM. The Riva voltage should be very close to what would occur with an E-power type devices. The RMS voltage and PWM are mentioned because measurement of the voltages is typically not possible with multimeters or voltage meters commonly possessed by e-cig users. Voltages measured on DC voltage scales of common multimeters will not register RPM volts if PWM is occurring.

The Booster RMS voltage is the most difficult to get to with confidence. The Booster, so I understand, is a SMPS (switching mode-power supply) type device. As such, it has "reactance" in its circuit that makes measurement of its RMS voltage difficult for people like me, someone with limited skills in the area. What is reflected for the booster as its RMS voltage is the sum of 0.46 volts and the RMS voltage of the eGo without booster. The 0.46 comes from 0.8 (the difference in voltage shown on the oscilloscope in the youtube mentioned above) divided by the square root of 3. Possibly this calculation is wrong but nonetheless the number of "hits" derived ends up coinciding with results obtained by vocr. Comments on the "correct" method of getting to proper results of the Booster's power impact at the atty would be appreciated.

A question might be does what appears to be relatively small variation in power between the considered devices justify the added costs. The current price of the EM Riva is in the vicinity of $12. Ths Joye eGo - about $15.60. The VV eGo about $30 and the eGo Booster about $60 (with which a $15.60 battery is needed). It should be noted that a change from a standard resistance atty of 3 ohms to a low resistance one of about 2 ohms, changes power at the atty by a 50% increase over standard.

[MasterofChaos]

JW50,

A very interesting result! As far as "reactance" of the eGo Booster circuit is concerned, I assume you are refering to its dynamic nature rather than reactance as the imaginary part of impedance? If that is what you mean, then keep in mind that the eGo Booster circuit operates at a frequency of 2.4 MHz, which is typically too high a frequency to affect the measurment at close to DC frequencies. It also means that the booster can change its behaviour (or "react" if that is what you are referring to) quite quickly, since the output voltage will change according to some number of switching cycles (it might be 100 or so cycles, but at 1/(2.4 MHz) each cycle is only 416 ns).

Thank you for spending the time to produce this data! This also confirms what I suspected about the so-called 'VV eGo" battery, which is that it really is just a "Riva Reducer", or a Riva that they put a varying duty cycle pulsing circuit on to reduce the power going into the atty.

One more thing that's important to remember, is that a lot of the eGo Booster's behaviour is a result of what the eGo battery is doing, and is out of the Booster's control. If you put the eGo Booster on a mod with an 18650 battery, for instance, what you have is effectively a Provari (without the flashy display) that only goes up to 4.7 volts.

[JW50]

Some interesting (at least I think so) info from another post. The post provides voltage versus mAh graphs for specific batteries that might be used in an e-power. Post is here: Battery Tests
Data at this post suggests that the number of "hits" shown in my graph may be too high. It also indicates that some batteries do not have the sharp drop off of voltage that is depicted above toward end of charge life.

[JW50]

Chaos - No, by "reactance" I did mean increased or decreased impedance. I am not at all confident in the calculation. But I added 0.46v to the RMS voltage of the eGo. On scope the apparent difference that the Booster provided was 0.8 volts. I took this 0.8 number and divided it by the square root of three. This lesser amount was what I presumed to be the RMS add. I gained a bit more confidence in the number when my calculations showed that the number of "hits" in a re-charge life was reduced for the Booster as compared to the eGo in a manner consistent with vocr's actual results. But, not total confidence, as his numbers used different attys between the two. The square root of three number comes about from the changing current at the high frequency (not the eGo duty frequency). That changing current is indicated in the Wikipedia article here: Boost converter - Wikipedia, the free encyclopedia
Still, the one over square root of three multiplier did not quite jive with what I saw on the scope. Although that was looking at voltage - not current. But when I actually measured DC voltage with Booster at high on an eGO, and loaded, I got varied results (from 0.61 to 1.11 difference) which to me indicated instability somewhere. That took me back again to vcor results as reasonable "confirmation" that 0.46 was correct. If there is a more accurate way to go about getting to the real power that the Booster adds at the atty - I'm all ears. But I'm inclined to believe it is not the 150% or 161% of the eGo as you have suggested in other posts at times. BUT - I'm not saying the eGo Booster is bad. Personally, I think too high of a voltage would be bad - which I don't think the Booster goes to.

[JW50]

Would a Booster work on a VV eGo if the VV eGo was set to low or middle? Would a Booster harm the VV eGo batt?

[MasterofChaos]

Since the 'VV eGo" is just a Riva with a duty cycle reducing circuit (I like to call it the "Riva Reducer" or RR), I doubt it would work.

Its neither Variable (switchable) nor an eGo, really.

[MasterofChaos]

JW50,

As for measuring a particular power increase, remember one important fact: The amount of power increase will be related to the atty you use. All the claims for the Booster are with SR (2.2 - 2.5 ohm or higher) atties. You certainly wouldn't get a 150% increase with an LR atty, since LR atties max out the eGo battery at a very low voltage.

And every atty is a little different so the amount of increase you get should expect to vary from atty to atty as well.

[JW50]

JW50,

As for measuring a particular power increase, remember one important fact: The amount of power increase will be related to the atty you use. All the claims for the Booster are with SR (2.2 - 2.5 ohm or higher) atties. You certainly wouldn't get a 150% increase with an LR atty, since LR atties max out the eGo battery at a very low voltage.

And every atty is a little different so the amount of increase you get should expect to vary from atty to atty as well.

I'm thinking you're missing the results of my calculations. I'm showing that the eGo Booster is increasing wattage by 28% as compared to the eGo without Booster and about 13% as compared to the Riva at about hit #300 or so. Just off charger, eGo plus eGo Booster is only slightly above the Riva. This at SR ohms levels. Although calculations and thought process may be in error, I found figure 3 of the Wikipedia article relevant. Note in that figure 3 that there is a constant voltage boost (i.e. V sub o minus V sub l) but current is changing in a sawtooth pattern from I sub s to I sub l. The sawtooth I produces an RMS current of 1 over the square root of 3 times the current differences there. The current difference there is the same as the voltage boost divided by R. That is, the RMS voltage boost is a bit more than half of the voltage boost that might be seen on the scope.

Then considering the 128% compared to the eGo. Square root of 1.28 is 1.13. One over 1.13 is 88%. That is, eGo plus Booster will have 88% of run time as eGo without booster. (There about - approximately - since that 1.28 factor is not constant throughout a discharge cycle. vocr had data that showed about 89 to 90% - comparable to the 88% indicated here.)

Finally, at first glance it would seem that LR versus SR would same effect on the boost voltage as on the unboosted voltage - percentagewise. That is, lowering of R causes V sub l to be higher but difference between V sub o and V sub l is proprtionally higher as well. That is, the 128% number would seem to apply to both LR and SR.

[MasterofChaos]

Sorry dude, your totally wrong there. You calculations don't make any sense.

But that's okay, I admire your tenacity! Keep on measurin' and if you keep on calculatin', you'll get there eventually!

Best wishes and Happy vaping! :-)

[JW50]

Sorry the calculations made no sense. Perhaps I was too fast with the math. Lets look at the "heat" at the atty in a boosted condition and compare it to a non-boosted condition. Make a comparison ratio of the two. Call one, "heat-boosted" and the other, "heat-ego". Call the ratio "BovE Ratio". Therefore, from definition heat-boosted divided by heat-ego equals BovE Ratio or symbolically (heat-boosted)/(heat-ego)=BovE Ratio. Heat might be expressed in watts. So the BovE Ratio would be the same as watts at atty in boosted condition (or shortened "watts-boosted") divided by watts at the atty in non-boosted condition (shortened to "watts-ego").

So, from the graph at about hit #300 or so, watts-boosted is 128% of 4 watts and watts-ego is 4 watts. 128% times 4 watts divided by 4 watts produces the number 1.28. That is, the BovE Ratio equals 1.28.

We also know from ohms law that current squared times resistance equals watts (presuming current is expressed in amps and resistance in ohms). Express current with symbol "I". Express resistance with symbol "R". So watts is I squared times R which is symbolized as I^2*R. The watts at the boosted state is (I-boosted)^2*R. The watts at the non-boosted state is (I-ego)^2*R. And the BovE Ratio using these facts becomes (I-boosted)^2*R divided by (I-ego)^2*R. Because R divided by R is 1 that factor can be removed from the comparison and the ratio becomes (I-boosted)^2 divided by (I-ego)^2 or symbolically expressed as (I-boosted)^2/(I-ego)^2. Since it is a ratio, the (I-boosted) can also be milliamps as long as (I-ego) is also milliamps. Symbolize milliamps as mA. So the ratio is (mA-boosted)^2/(mA-ego)^2 is same as ratio (I-boosted)^2/(I-ego)^2.

So, from above one has (mA-boosted)^2/(mA-ego)^2=1.28. Using this equation one can take the square root of both sides of the equation (getting mA-boosted/mA-ego= square root of 1.28) and the equalization still exists. So, (mA-boosted)/(mA-ego)=1.1314.

Of course, battery capacities are usually rated in milliamp-hours or (mAh symbolically). Since capacity is capacity, the (mA-boosted) times the time of boosted use equals the (mA-ego) times the time of ego use. Or, symbolically (mA-boosted)*(time-boosted)=(mA-ego)*(time-ego). But, for the type of comparison desired the interest is time-boosted as compared to time non-boosted. If the ratio of time-boosted to time non-boosted is greater that 1 then that would mean greater time boosted than non-boosted or if the ratio is less than 1 then less time boosted than non-boosted. And whatever that ratio might be, one could multiple it by 100 and express the results as a percentage. If that percentage is say 125% then that would mean 1.25 times the (time-ego) as the amount of time for (time-boosted). If that percentage is say 75% then that would mean 0.75 times the (time-ego) as the amount of time for (time-boosted).

So, using these facts we have (mA-boosted)*(time-boosted)=(mA-ego)*(time-ego). Re-arranging terms using ordinary algebraic operations we get (time-boosted)/(time-ego)=1 divided by (mA-boosted)/(mA-ego). Or expressed symbolically:

(time-boosted)/(time-ego)=1/square root BovE or 1/1.28^0.5 or 1/1.1314 or 0.8839 or approximately 88%

That is, time-boosted will be about 88% of time as would be case if not boosted to the end of battery capacity. vocr results showed that with Booster set at high that run time was, on average, 89.5% when he used a 650 mAh battery and was, on average, 88.0% when he used a 1000 mAh battery.