Battery Voltages -- Surprise!

[Stonemull]

would like to see the calculated RMS on the plot from the CRO peak and duty cycle measurements.. should match the CRO RMS though pretty well.

 

[Rocketman]

"Peak" as displayed on the DSO is a math function, compensating for the AtoD 1 bit noise and any single sample overshoot.
Displayed "Duty Cycle" is a function calculated from the 30% (I believe) amplitude points.
The DSO calculated RMS takes the rise and fall into the calculations, as well as any amplitude variations in the positive pulse, using all samples. The displayed RMS value is the RSS of all samples in the waveform.

Kind of hard to do manually, and I don't have the data interface for the scope to extract sample data. Manual calculation might not be as good as the measurement and calculations that the scope does by software.

For example:
If the tops of the positive pulses were not flat, the amplitude and Duty Cycle displayed on the DSO would probably be the same. The RMS would be different because the individual samples would not be the same.

The peak is the amplitude of the "tallest pulse". That would "inflate" manual calculations.
Duty cycle is the average of all the pulses in the sample (about twice the length shown).

 

[Rocketman]

Here are the eGo 1.6ohm screen shots.

Notice that at +85 minutes the Duty Cycle went unstable, and that at 105 minutes it went to 100%.
No pulse waveform during the sample period so I took Vmax instead. This is probably o.o4 volts high because of A/D noise bit.
I was going to take another shot, but it quit at about 107 minutes.
Pic 1: Full charge
Pic 2: +15 minutes
Pic 3: +30 min
Pic 4: +45 min (blurry pic, bumped camera, values added in pic as text)
Pic 5: +60 min

 

[Rocketman]

and the remaining screen shots.
Pic 6: +75 min
Pic 7: +85 min
Pic 8: +90 min
Pic 9: +100 min
Pic 10: 105 min
No Pic: cutoff @ 107 minutes

(guess that's the reason I don't use e-cigs with leetle batteries )

JW,
Do your stuff

 

[DaveP]

Guys, I enjoyed your analysis of the Ego batts, but aren't we talking about an RMS reading on a pulsed DC voltage here? RMS is the DC equivalent of an AC sine wave for power calculations according to my electronics training. It was developed to calculate the power average of a signal with a slow rise time compared to a DC voltage. I remember that being .707 x peak = RMS ( for a sine wave AC signal).

The thumb on the atomizer barrel is the crop duster equivalent of efficiency, IMO. If the Riva makes the barrel warmer than the Ego, then we can say that the Riva is providing more power to the atomizer coil.

Here's a discussion of PWM and RMS.
What are the peak and RMS values of the voltage of a pulse-width-modulated signal

 

[Rocketman]

The thumb on the atomizer barrel is the crop duster equivalent of efficiency, IMO. If the Riva makes the barrel warmer than the Ego, then we can say that the Riva is providing more power to the atomizer coil.

Actually Dave, we are over 600 posts here not discussing crop dusting, and thumb control of vaping power, but what is going on with the eGo as far as voltage/power control, and why one method of obtaining consistent power to the atty/carto is better than another

Just as some like high voltage vaping compared to 3.7 volt vaping, the automated consistency afforded by the eGo Magic circuitry appeals to some, thumb modulated power control appeals to others. Some like automated power control so much that they need a Darwin to feel satisfied.

Back in the day, I would modulate the puff I took on a cigar to modulate power. Harder, longer puffs when I needed a bigger 'hit', slow and light puffs when relaxing. If I wanted a smoke that lasted longer, I lit a bigger cigar. I sort of do that now with my unregulated e-cigs.

At least half of the posts in this thread have discussed what is going on in the eGo with it's PWM algorithm and just how 'flat' the result is and how this is better than, or not better than, some other method. The other half of the posts have been about measurements and calculations. We've seen 'teaser' screen shots of eGo PWM waveforms, assumptions as to what the intent of the design was, and how well this works for the vaper that doesn't want to think about manual power control. Some don't care what's going on inside, but seem to like one method over the other.

For 3.7 volt vapers the options are unregulated batteries with fall off in power with time, bigger and bigger batteries to make that fall off slower, or a more consistent but lower power delivery from a eGo with automated PWM.

(then we drifted off track and started talking about measuring the eGo with a Cheapo meter )

 

[JW50]

Charting of Rocketman's experiments:

[/URL] Uploaded with ImageShack.us[/IMG]

 

[Rocketman]

Wow, that's BUSY

But, if you mentally expand the 1.6 ohm graphs to the same end point as the 3 ohm graphs then they look similar.
(except power)

Thanks for the chartsmanship.

An observation:
The final minutes with the 1.6 ohm went to 100% and the power went up slightly. The vape improved just before cutoff. With the 3 ohm, the vape got weaker in the last minute.
I wouldn't try and interpret fluctuations or erratic results than are within the uncertainty of the measurements.
Remember that at 3.5 volts, +/- 2% is +/- .7 divisions on the graph.

 

[JW50]

Well - I agree it is busy - but some trade-offs made to get on one chart. What strikes me is the consistency of the power. The more exact numbers for the 1.6 ohm atty were 7.44 watts +/-4.6% and for the 3 ohm - 4.03 watts +/- 3.5%. Plus or minus 3.5% or 4.6% is really quite consistent. A Darwin may have a setting that says 12 watts (or whatever) but that would, I would think, really be 12 watts +/- probably a few percent. Variation of +/- 3.5% over the discharge cycle is really, I think, pretty close to constant.

I also noted from your 1.6 ohm experiment that duty stayed fairly high. But, lower the ohms, higher the duty - so it seems. But, what o' what caused that 64% (there about) duty on the eGo plain in the eGo Booster video?

I also note that the ratio of 3 ohms to 1.6 ohms is 1.875 and the ratio of 200 minutes to 107 minutes is 1.87. That means to me that there was not much self regulation in your vaping. (Nothing wrong with that. Just not much "longer, harder puffing" going on.)

 

[Rocketman]

Not dissing your chart, all the info is there.

I think the 107/200 was 'luck of the draw".

I haven't used an eGo Booster, but 64% Duty Cycle must be for the "Low" setting.
It makes sense that in order to drive a lower resistance (1.6 ohm vs. 3 ohm) the eGo has to try harder.

One thing that does not show in ANY of my scope shots is the initial turn-on, startup waveform. The first several cycles start out at a much lower duty cycle then increase and stabilize. I delayed the scope trigger to eliminate this variable period from the measurements. Maybe the 64% was the startup burst. 20 to 30 pulses out of a total of 500 per vape.

I'm pretty sure the Darwin has better power control than the eGo. I would expect first order measurements in the Darwin circuit to be within 1%, and power measurement to be within 2%. (two 1 % measurements, errors related).

Maybe I'll post the Cheapo meter readings of my 26650 or parallel 18650 and compare it to the eGo (about 16 hours per charge), and we can graph that

 

[JW50]

Charting with a different X axis.

[/URL] Uploaded with ImageShack.us[/IMG]

X axis here proportional to mah use. Still busy but perhaps a bit less. Some features that demonstrate some "magic": Peak power goes down with with lower ohm atty (internal resistance taking higher bite of cell volts) yet RMS voltage and cheapo average DC voltage nearly constant for either case. Very consistent watts throughout discharge cycle although fading a bit as you go. Regulation is more closely proportional to RMS volts than to DC volts.

 

[Rocketman]

That one I like. Looks really interesting.

If the eGo starts with about 3.9 volts loaded from a 4.2 volt unloaded cell, and gives a fairly constant 7.5 watts (1.6 ohm is probably the best for this voltage) just think what it could do with a bigger cell.
I don't mean higher voltage, but just the eGo circuit and a Big Battery about 3 to 4 times the mah. Imagine the 1.6 ohm curves stretched out. I like the slightly higher voltage I get from an unregulated big battery, but the eGo 1.6 ohm test did give enough vapor. At least for me. I just can't stand the stress of running out of battery power

I might rip an ego apart and plop it on top of a Big Battery mod and compare totally unregulated to the eGo circuit on the same mod. Less power but flatter, and probably enough vapor for me.

This is the style I'm talking about. It has an eGo connector on it already.

 

[JW50]

If one thinks of an eGo "experience" as vaping at 3.7 volts, then using the 1.6 ohm atty on the eGo instead of a 3 ohms atty is the equivalent of that 3 ohms on a consistent 5 volt device. And if one thinks of an eGo batt as lasting only for 300 charges, vaping at that equivalent of 5 volts will reduce reduce your eGo's life by close to 50%.

 

[JW50]

That one I like. Looks really interesting.

If the eGo starts with about 3.9 volts loaded from a 4.2 volt unloaded cell, and gives a fairly constant 7.5 watts (1.6 ohm is probably the best for this voltage) just think what it could do with a bigger cell.
I don't mean higher voltage, but just the eGo circuit and a Big Battery about 3 to 4 times the mah. Imagine the 1.6 ohm curves stretched out. I like the slightly higher voltage I get from an unregulated big battery, but the eGo 1.6 ohm test did give enough vapor. At least for me. I just can't stand the stress of running out of battery power

I might rip an ego apart and plop it on top of a Big Battery mod and compare totally unregulated to the eGo circuit on the same mod. Less power but flatter, and probably enough vapor for me.

This is the style I'm talking about. It has an eGo connector on it already.

Personally I like the style you have selected there and like the idea of a life of charge better than an hour and a half, hour and 40 minutes.

 

[Stonemull]

the main thing I noted with the graphs was that there was very little difference between the RMS voltage for the 3Ω and the 1.6Ω, so I reckon the ego adjusting to atty resistance thing can be totally put to bed, it looks like some effort was made to regulate towards the rms voltage as opposed to a simple linear duty vs battery voltage algorythm.
The increase in performance towards the end is also interesting, but whether 5% power variation is even noticeable over a battery charge is arguable. ( i guess that means argument will follow )
overall .. I would say that the ego is pretty well regulated at least as far as vaping goes. who needs 1% accuracy .. now if it was adjustable..

btw .. all my ego's are in storage and have been for months, I'm a provari man and making me own mod. in the final stages of prototpe, i did learn a little from this thread so far though, good stuff.

 

[Rocketman]

Stone,
we have over 300 posts before we make it to 1000. Plenty of room for "arguments will follow". For me the eGo is sort of weak. Works for the wife, but I could adjust. I might put together a big battery eGo just for the fun of it. Probably wouldn't be my favorite device, and could always change it over to a straight 3.7 volt e-cig if I didn't like it.

I've got some new ones in storage (spares for the wife). She wouldn't even miss one of them.

Just think. A 4000mah eGo.
I could call it the FA-TeGo

 

[Stonemull]

Guys, I enjoyed your analysis of the Ego batts, but aren't we talking about an RMS reading on a pulsed DC voltage here? RMS is the DC equivalent of an AC sine wave for power calculations according to my electronics training. It was developed to calculate the power average of a signal with a slow rise time compared to a DC voltage. I remember that being .707 x peak = RMS ( for a sine wave AC signal).

The thumb on the atomizer barrel is the crop duster equivalent of efficiency, IMO. If the Riva makes the barrel warmer than the Ego, then we can say that the Riva is providing more power to the atomizer coil.

Here's a discussion of PWM and RMS.
What are the peak and RMS values of the voltage of a pulse-width-modulated signal

not quite sure what you are getting at, rms applies to any varying voltage, it does not have to be a sine wave, this area of the discussion came into being as people where measuring the output of an ego battery with averaging meters and calculating power in the atty from that reading, it was pointed out that this is incorrect as the peak voltage must be known as pointed out in the link you posted. There is no way of therefore measuring the power with a non rms meter without also finding either the duty cycle (from which peak can be calculated) or rectifying and capturing peak on a cap as I pointed out.
A true rms meter however can be used to measure the pulsed DC rms voltage and calculate the power directly, its entirely applicable to the discussion.
Whether any of it makes much difference ( at > 80% duty cycles) apart from knowing the ego regulates is another matter
I must have missed the part of the thread with the 64% duty cycle, errors between Vave and Vrms would be quite a lot here ..

 

[Stonemull]

Stone,
we have over 300 posts before we make it to 1000. Plenty of room for "arguments will follow". For me the eGo is sort of weak. Works for the wife, but I could adjust. I might put together a big battery eGo just for the fun of it. Probably wouldn't be my favorite device, and could always change it over to a straight 3.7 volt e-cig if I didn't like it.

I've got some new ones in storage (spares for the wife). She wouldn't even miss one of them.

Just think. A 4000mah eGo.
I could call it the FA-TeGo

sssh .. the chinese are listening ..

tho I think that one is unregulated, full battery volts..

I have a 510N mod which is a stainless steel ego pcb tube mod that takes 18650's, bought it for dual coils but its not that good with the LR stuff, good battery life though

 

[JW50]

Guys, I enjoyed your analysis of the Ego batts, but aren't we talking about an RMS reading on a pulsed DC voltage here? RMS is the DC equivalent of an AC sine wave for power calculations according to my electronics training. It was developed to calculate the power average of a signal with a slow rise time compared to a DC voltage. I remember that being .707 x peak = RMS ( for a sine wave AC signal).

The thumb on the atomizer barrel is the crop duster equivalent of efficiency, IMO. If the Riva makes the barrel warmer than the Ego, then we can say that the Riva is providing more power to the atomizer coil.

Here's a discussion of PWM and RMS.
What are the peak and RMS values of the voltage of a pulse-width-modulated signal

Not sure I would agree that RMS reading is the equivalent of an AC sine wave for power calculations (for PWM). I think the relationship you mention might be AC RMS Voltage = E/√(2) where E = Peak Voltage -Average Voltage. 1/√(2) = 0.707. In the article mentioned earlier relating to what meters measure, it seems pretty clear that cheapo meters are pretty close in readings when it comes to RMS on the AC function if input is a sine wave. But give the meter a pulsed DC signal, a reading may be present but it is unlikely to be RMS or even a sine equivalent of RMS.

The thumb measure certainly works at times. But, I think more than thumb, it is - "I like this" or - "I don't like this". Thumb may play a role there - but not 100% - usually. In thinking about the thumb - how is you conclude that Riva is better (or worse) than eGo. What if I say it was the atty that made things different? I think part of discussion here is like - why is my wine better that yours. Both have alcohol but mine (according to me) has more aroma and flavor - which helps me get to where we are both probably headed.

 

[Rocketman]

Stone:
the big eGo looking thing (free if you order $250) takes an 18650.
The big mod in MY pic has a 26650 in it

And watch out for the "True RMS Meter" that won't do anything but AC sine.
Read more than the "specifications" in the operators manual. Many will not do a waveform like the eGo output.

RMS measurements are easy with pure sine wave or pure DC. It's a little harder with complex waveforms.
I used to calibrate some pretty crappy, but expensive DMMs.

I took eGo #2 apart. No more measurements from that one. Leads soldered and ready for installation in the Fat-eGo
But not tonight.