Bloog MaxxFusion voltage regulation

[pmos69]

From time to time, someone posts doubts about the regulation in BMF batteries.

To help put an end to confusion/misinformation, here´s a reading of one of my 65mm, many months old, BMF auto.
Unloaded reading - charged (old) battery

For anyone not familiar with regulation methods, that's a typical PWM regulated output, and the relevant value for power calculation is RMS (Root Mean Square Voltage - Basically the equivalent DC voltage)

 

[Ghostrider]

For those of us that aren't electrical engineers.....what does that mean?

 

[leaford]

WOW!! Thanks for that, PMOS! Our manufacturer tests the working voltage using a multimeter-like device, using a custom made rig to attach the battery and still allow it to be activated, which has a simple LED digital output, so I've seen the testing being done, and I've seen the log books (which are in Chinese, of course except for the numbers ), but I never had anything I could SHOW like that! Bravo! Bra-freaking-vo!!!

And Ghostrider, I'm not conversant in that sort of computerized output either, and maybe PMOS can translate the key on the side for us and correct me if I'm getting this wrong, but the graph seems fairly straightforward. This is the output of a test cycle, testing the battery for it's voltage output at rest, and when in use, over a period of time.

The blue lines are a representation of the voltage output. The lower line, labeled "1" would be the voltage at rest, and the upper line, labeled "T" would be the working voltage, the output when in use. The left-right value would be the time factor, but I'm not sure if it goes left to right, or vice-versa. So, the blue line rises upward with each puff, plateaus during the puff at 3.6v, then goes back down to the resting voltage in between puffs. (At least I am assuming these are longer puffs with short pauses in between; if it's short puffs with long pauses in between then the lower line is the working voltage and the upper line the voltage at rest, but the principal is the same either way.)

And the point of it all is that the normal, unregulated, profile for other e-cig batteries would not be a straight line. Unregulated output voltage will vary along with the battery's charge, from a high of 4.2v at full charge, to a low of 3.5v when fully depleted. So the spikes for that would be higher on one end, and lower on the other, as the charge is expended. Whereas the Bloog MaxxFusion is regulated at 3.6v output, so both resting and working voltages form straight lines when graphed.

Again, PMOS, Bra-freaking-vo!!

 

[pmos69]

Hey Leaford, you got the timescale wrong, but that's close
(That's actually a 200ms sample while the battery in on and doing it's regulation magic)

Trying to explain in simple terms first, for those without electric/electronics training:

Unregulated batteries just pass along their "native" voltage to heat the cartomizer when vaping. In the case of lithium based batteries, like most e-cigs use, that actually means you start vaping at 4.2Volts (the voltage when the battery is fully charged) and end up vaping at about 3.5Volts (when the battery is near empty).
That actually translates to a substantial difference in the heat produced in the cartomizer, and so a very different vaping experience.

To avoid that, the BMF was actually the first 808 device i know to have introduced a form of voltage regulation - and a very effective one at that.
The regulation method used is called PWM (Pulse Width Modulation - in geek language)
The only other mass produced device I know from that time to have a similar (not exactly the same - just similar) voltage regulation scheme is the eGo.
In the mean time, other manufacturers seem to have introduced voltage regulation schemes in other 808 mini e-cigs, but I'm not in a position to evaluate that. At the time, the BMF was the only one.

So what does PWM do? Simple - It basically turns the battery on and off at a very fast rate - 53 times per second, in the case of the BMF - So fast that in practical terms you won't even notice it or are able to detect it.
The end result is that, since the battery is only "on" a part of the time (90.53% of the time in the case of the reading above for a charged battery), the final output will have an "equivalent" lower voltage.
As the "real" battery level starts getting lower (down from 4.2Volts all the way to 3,5Volts), the voltage regulation circuit simply adjusts by increasing how much of the time the battery is "on" in relation to the time it is "off". Near the end of the battery charge, the battery is "on" just about 100% of the time.

Explaning the graphic above then:

Horizontal Axis (The timescale): 20ms per division - 200ms for the whole graph

Vertical Axis: The battery output in Volts - 1 Volt per division

The (cyan) Line: The actual battery output as it varies in time.

The 2 dotted horizontal lines:

1 > Just indicating 0 Volts, to give a reference.​

T > Ignore that - It's just a trigger level to help the oscilloscope get a stable reading​

RMS: The actual "equivalent" voltage to a normal battery with no regulation - 3.76V (but remember I'm reading this with no cartomizer attached - Voltage in real usage will be a bit lower)

FRQ: The frequency at which the output is doing it's on-off dance - 53 per second in this case

DUT: Duty cycle - The percentage of time the battery is actually "on" - 90% in this case, which means it will be "off" 10% of the time (duh!)

MAX and MIN: Maximum and minimum voltages, as the battery turns "on" and "off" - you can disregard the 0,4mV as an adjustment error - Vpp actually gives a more accurate value.

Vpp: Voltage difference between "off" and "on" - Actually a more accurate reading for the maximum voltage:

battery "on": 4 Volts
battery "off": 0 Volts​

As I said, this is a reading with the battery almost fully charged.
As the battery charge drops, along with its "real voltage" the PWM circuit should increase it's "Duty cycle" (DUT) to compensate for that, and provide a constant vaping experience.

and... I'll end this here, or I won't shut up.

 

[pmos69]

Just one more tidbit:
"Normal" DC multimeters have a dificult time getting accurate readings of PWM modulated voltages.
An oscilloscope or a "true RMS volmeter" is needed to get accurate readings.

Depending on frequency and duty cycle of the wave, most DC multimeters will give a reading for the "average voltage" -> which is not the equivalent voltage and cannot be used to calculate the average power being delivered to the device.
The equivalent voltage is the RMS voltage, which is generally higher than the average voltage.

...and I won't go into detail about why it's like that and just shut up again.

 

[leaford]

Just one more tidbit:
"Normal" DC multimeters have a dificult time getting accurate readings of PWM modulated voltages.
An oscilloscope or a "true RMS volmeter" is needed to get accurate readings.

Well, I did say "multimeter LIKE device," and all I meant by that is that like a multimeter it reads the electrical voltage, amperage, ohms, and so on and gives you a reading.

It probably is an oscilliscope; it's a big box with plugs for various input and output cables and a couple of digital readouts. They actually have different ones for different tasks, all about the same but different input and output rigs, and IIRC off the top of my head, some have more digital displays than others.

Remember, I'm not an engineer and have no backgroud in electronics before this except a good grounding in basic science. I have been learning a lot as I go, but never really have time to learn as much detail as I would like on things like equipment and technical terms.

AND there is always a language barrier when it comes to translating any kind of remotely technical term, often including the names of devices, because the sales people who speak english and are doing the translation aren't even very familiar with the chinese terms, let alone the english ones.

 

[pmos69]

Oh - Wasn't meant to you, Leaford.

It's just that A LOT of people present readings in the forums made with DC voltmeters.
When they can't get a reading, they assume the device is doing some sort of regulation and the output is not linear, but when they can get ANY reading at all, most of the times it's taken as good, and that's not always the case.

 

[pmos69]

OK, then.
Here's the complete picture of the PWM circuit doing its magic.

Note: There's probably a small voltage drop introduced from the PWM circuit itself (about 0.2V), so when I state "X volts available from the battery" that's not the real voltage from the internal cell but just the "peak" reading after the circuit.

...and please remember, this is actually a battery with many months of multiple daily recharges and faithful service.

Fully charged (as seen before): 4V available from the battery Regulated to 3,76V (But this is only momentary as the voltage drops fairly quickly to the ~3,7 Volt range)
Entering the "main" vaping phase (most of the vaping time) 3.72V available from the battery Regulated to 3.52V
In main vaping phase 3.68V available from the battery Regulated to 3.44V Still didn't change the duty cycle, so it did get as low as 3.44V, but then...
Still in main vaping phase Voltage from battery keeps lowering - 3.64V available from the battery but duty cycle adjusted and output voltage actually got back to: Regulated to 3.52V
Still in main vaping phase Voltage from battery keeps lowering - 3.56V available from the battery but duty cycle adjusted again and output voltage actually is still: Regulated to 3.52V
End of the main vaping phase. After this, time to cut-off is fairly close. Around 15 drags. After the battery voltage reaches 3.52V, the PWM circuit stops modulating the output, and so a constant voltage is delivered Output: 3.52V
A few more drags and the rapid fall is visible. Output: 3.40V It's saying goodbye fast.
Just about to reach the cut-off level. After 3.2V stopped firing. Output: 3.20V

All in all, a great job at regulating such a small cell.
Voltage is stable at around 3.52V throughout just about the entire discharge cycle.

 

[redempti0N]

ahhhh my brain!!!

 

[pmos69]

ahhhh my brain!!!

But I put in the pretty pictures just for you!

 

[leaford]

Again, PMOS, thanks a whole bunch!! That's great data, and I'm going to bookmark this thread for future use!

 

[pmos69]

No problem, Leaford.
Had some free time, and the kids enjoyed seeing me trying to meter the batteries while blowing through the endcap :/

 

[popeye79]

wow, good stuff pmos!

maybe this should get a sticky!

 

[leaford]

wow, good stuff pmos!

maybe this should get a sticky!

Good idea! Done!

 

[bobthesalesclerk]

wow, good stuff pmos!

maybe this should get a sticky!

I think he deserves some free cartos as well lol

That must have been a pain getting those readings from an auto battery!

Great job!

sent from my Ice Cream Sandwiched Gtablet

 

[leaford]

I think he deserves some free cartos as well lol

That must have been a pain getting those readings from an auto battery!

Great job!

sent from my Ice Cream Sandwiched Gtablet

I agree, and I would have them sent, but he's in Portugal. But I'll ask 2Smok and see if they agree to it!

 

[pmos69]

I think he deserves some free cartos as well lol

That must have been a pain getting those readings from an auto battery!

Great job!

sent from my Ice Cream Sandwiched Gtablet

Nah
Thanks, but that would turn an independent analysis into a sponsored one. It's fine this way because that wasn't the intention.

I feel much better just enjoying the fact that, if the analysis had revealed any issues, I would still post it and that would still be welcomed by Leaford instead of being denied or censored.
That's what happened with the first version of the BMF cartomizers right on this forum, and later led to improvements in them, so this is not some smoke&mirrors sales pitch but an actual practice.
Although the same full disclosure policy may sometimes hurt Bloog when facing competitors, it translates into a higher trust in the company and its products. At least for me.

 

[tanikir]

What I'd like to see is the same tests done with competitor's batteries. I wish I had the equipment and knowledge.

 

[pmos69]

That would be difficult for me, as I'm not a battery colector
I have some other "pre-Bloog" kr808d-1 batteries, but they're not regulated.

Here's another voltage regulation example but from a completely different device, a 650mAh eGo (Ovale, actually):

As you can see, it uses a very different kind of regulation, although still PWM based.
(It also makes it clear why most people say eGos are 3,2V devices, when that's not the case. Even my toy scope's RMS metter was fooled by the very irregular wave)

 

[Frick]

Very nice data presentation. I see pbusardo (a youtube reviewer) using almost the exact same display off an oscilloscope.

It's nice to see this kind of in-depth research being done independently.

Mind if I ask what kind of scope you used?