Battery Voltages -- Surprise!

[Rocketman]

OK, so does anyone have RMS voltage measurements, like with maybe a DSO with curve calculating capability, to tell us what the RMS, under load voltage of an eGo really is?

Or is everyone guessing?

And stone, the startup load test is what you are referring to before the eGo goes into load control mode.

 

[br5495]

br;
seat of the pants works better than most think

Getting a "feel" for how your e-cig works is probably the biggest shortcoming of those searching for that mysterious "sweet spot". I also get all I need from somewhat normal voltages with straight through 3.7 big battery stuff, but mostly because of charge life.

Bet you wish you could have vaped while flying, no worry about blowing the cherry oput


(the eGo ain't all that smart. It puts out about the same voltage no matter what you hook to it. Unless you go too low or too high in resistance)

Yeah, true seat of the pants flying only came about for me when I was forced to do without all those extra gauges in the cockpit. For many years, all I had was four to monitor engine RPM, manifold pressure, oil temperature, and oil pressure.

Don't I wish I would have had e-cigs back when I was flying, especially during the open cockpit days. Keeping one lit was not a problem, but lighting it with a Zippo could be a challenge. But that's not the worse part. The worse part was when the slip stream stole my last pack out of my shirt pocket and I had to do without them for the rest of the day.

Actually, I don't still use the eGo as my main battery, but my wife does. I went to the Hello 016 because it regulates at about 3.1 volts instead of 3.2 volts. Just that slight change is enough to reduce my juice consumption to my requirements.

 

[Stosh]

br;
seat of the pants works better than most think

Getting a "feel" for how your e-cig works is probably the biggest shortcoming of those searching for that mysterious "sweet spot"............

+10 for this, how many posts...."I'm vaping at 3.7v and the vapor and taste are great!!
So 7.2v will be twice as good" ....

 

[JW50]

+10 for this, how many posts...."I'm vaping at 3.7v and the vapor and taste are great!!
So 7.2v will be twice as good" ....

Are you sure about the twice as good? Seems to me it might be the square of double - 4 times as good!

 

[Rocketman]

actually if you square the voltage ratio (but not take the square root of it) then that will be 4 times as good
darn, JW beat me to it.

This one is only 1.19 times as good as 3.7 volts RMS.
(parallel 18650, 3 ohm CE2)

and that's hotter than an eGo.
and no, that is not a RMS meter.


Just wish I knew what the true RMS voltage of an eGo was, under load.

 

[JW50]

the ego does PWM regardless of the load, any differences will be as pointed out above, due to the cell voltage dropping under load. This will affect the duty.
I have some CRO waveforms of ego somewhere, it starts off at about 85% duty cycle and drops within a 100mS or so to a duty based on the cell voltage under load. Frequency is around 85Hz from memory, this seems to have changed a bit in the later versions.
I don't think you can get a correct Vrms voltage reading with a cheap multimeter using ac V or dc V or any math tricks .. The method Rocketman indicated is a bit pointless .. square anything and take the square root and you end up with the same data you started with (unless it was negative, you will now have a positive result, unless you are using complex numbers in which case you end up with an i in the result).

Long story short .. you cannot accurately compare output power on mods that use PWM unless you know the actual cell voltage at the time of measuring the Vave, to find this you could make a little rectifier cct with a diode and a capacitor and measure the rectified peak voltage on the cap .. add about 0.5v for a cheap diode and you have Vp, measure the dc v before the diode and you have Vave, compare Vp to Vave and you should get a good value for the duty cycle. Using the dc and Vp you can calculate Vrms fairly well.

Not sure I agree here. Rectify a positive or zero wave form and you get the same positive or zero wave form back. Just like squaring a square root. Also disagree that one can not get a correct Vrms using a cheap multimeter using ac V/dc V. But both numbers needed and knowledge that the ac V is determined from a full cycle and variance from the non-rectified average. Calculation is not particularly straight forward - but calculable nonetheless. The use of the two reads not much different than using other means in determining Vp and using it in connection with dc.

 

[JW50]

actually if you square the voltage ratio (but not take the square root of it) then that will be 4 times as good
darn, JW beat me to it.

Note - beat you by a full 60,000 mS.

 

[Rocketman]

I get something indicated with my cheap meter.
It is accurate
How can I say that?
I just don't say HOW ACCURATE.
The 3.29 volts I got are repeatable and not that far from the 3.25 volts.
I bet the true RMS voltage is between 3.1 and 3.5 volts.
That is the best estimate I have seen from folks talking RMS voltage.
Is my cheap meter within 10% of RMS, with a 50% probablility of indicating a little lower than RMS?


If I say that based on my 3.29 volt Cheap meter DCV test, that the RMS output under load is 3.3 volts +/- 5%,
who can do better?

And give a little explanation of errors in YOUR measurements.


and taking the square root of a square does not always give me the same answer.
I take the best 2 out of 3 results.

 

[Rocketman]

Note - beat you by a full 60,000 mS.

I am using a PWM bluetooth keyboard
(or you wouldn't have had a chance)

 

[JW50]

actually if you square the voltage ratio (but not take the square root of it) then that will be 4 times as good
darn, JW beat me to it.

This one is only 1.19 times as good as 3.7 volts RMS.
(parallel 18650, 3 ohm CE2)

and that's hotter than an eGo.
and no, that is not a RMS meter.


Just wish I knew what the true RMS voltage of an eGo was, under load.

LED volt readouts like one might get from madvapes don't read anything if PWM input. That the LED readout is reading 4.04 in your picture may mean you have RMS volts of 4.04 (since not PWM). For PWM voltage of eGo, as I've said, I think it is volts on your cheapo DC scale divided by square root of duty cycle. But, why not have your own scale. Make it dc volts times a factor. Call it volts raf or Vraf. If vape is good, factor is two. If not so good, factor is one. So if cheapo meter reads 3.25 and vape is good - Vfaf is 6.5. If vape not good, Vraf is 3.25. raf is for Rocketman adjust factor.

Surely there is someone out there with a RMS meter that can give Rocketman a RMS voltage of a loaded Joye eGo. Load of approximately 3 ohms with batt just off charger might be one. Then maybe a 1.5 ohm (+ or - but given) load for another.

 

[JW50]

and taking the square root of a square does not always give me the same answer.
I take the best 2 out of 3 results.

I think this occurs from using a cheapo calculator. Or, from the little guy inside that calculator miscounting fingers.

 

[Rocketman]

First you call my meter cheap, now it's my calculator?

(RMS calculating cheapo DMM)

 

[JW50]

First you call my meter cheap, now it's my calculator?

(RMS calculating cheapo DMM)

Apologize if I offended. How much above a dollar was that calculator?

 

[Rocketman]

Apologize if I offended. How much above a dollar was that calculator?

Is that with tax?

 

[JW50]

Is that with tax?

With tax but only if actually paid without use of cheapskate exemption. I think you are trying to avoid a negative answer on that calculator question!

PS - Mail in rebates should be deducted.

 

[progg]

Excuse the interruption, I just wanted to thank you guys.

“The happiest people are those who think the most interesting thoughts. Those who decide to use leisure as a means of mental development, who love good music, good books, good pictures, good company, good conversation, are the happiest people in the world. And they are not only happy in themselves, they are the cause of happiness in others.”

William Lyon Phelps

 

[Rocketman]

progg,
you're very welcome.

Thought provoking discussions can be very productive.

As long as someone doesn't get their feelings hurt and take their cheap meter and cheap calculator home, hummmph

 

[Rocketman]

deleted, just too much





and I still would like to know the RMS voltage from a typical fully charged eGo?

 

[JW50]

Relating to RMS voltage and "common" voltmeters the link that follows provides some interesting information about what AC voltmeters measure. The link is : http://home.comcast.net/~loudgpz/GPZweb/ACvoltmeter.pdf
The article at this link is titled

What does an AC voltmeter measure?

Relating to the cheapo of cheapo meters the following is extracted from page 8 of the link:

Update 7/12/09: Since the initial writing of this paper, a few ultra-low priced meters have become
available. These are typically made in China and retail for less than ten dollars, and often less than five
dollars. These meters employ a different approach to measuring AC voltage. It was discovered that they
simply eliminate the negative portion of the voltage wave by means of a half-wave rectifier, take the
average of the positive portion, and double it. That is, AC voltage = 2 times the average of the positive half
of the voltage wave. This type of meter can easily be identified because it will not register any AC voltage
if a battery is placed on the test leads with negative polarity, but will show twice the DC value of the battery
voltage if the battery is placed on the test leads with positive polarity.

Another extract:

A voltmeter is used to measure DC voltages and AC voltages.
The DC voltmeter is not measuring RMS voltage. When one is measuring the DC component of a
waveform, one would usually like to ignore the AC component. The DC component is the average voltage
of the waveform. The average voltage is easier for a meter to measure than RMS, so it is fortunate that one
usually only wants the DC average value, and not the RMS value. When a voltage waveform is a constant
value (i.e. pure DC), the DC average voltage and the total RMS voltage are the same.
However, there are instances when the total RMS value is very different from the DC average. Any time
there is a repeating change in voltage, the DC average is likely to be different from the RMS value. The
significance one must realize is that the energy delivered by such a fluctuating voltage is more than what the
DC average value would indicate. Therefore, it is important to know if a significant AC component exists in
the waveform.
To measure the AC component, one would use an AC voltmeter. However, most low-cost voltmeters also
won’t measure RMS when measuring AC. In this case, however, it is not because it is not desired, but
because it is not easy to do. Very expensive voltmeters are often made to measure “true RMS”, because that
is what is desired.

Some examples are given in this article of some measurements made with a lower cost Fluke meter. It is interesting to note that there is frequent variance between what the meter shows and what the real values are. That is, approximations are used in the metering circuitry and closeness of fit will vary with differing inputs. Hundredths of volts is probably false accuracy on inexpensive meters and in some cases tenths of volts may be questionable.

 

[Stosh]

If the RMS value is to be exact you need to do the math:

Vrms = √ ( 1/T ) [ ∫ V1 ² dt + ∫ V2² dt..+∫ Vn² dt ]