Ups, sorry, my typical back-of-the-envelope mistake.

I see an Vpp of around 25V on your oscilloscope, so the 6V amplifier setting is the next big no-go? He is limiting to 21V anyhow and probably wasting addition energy that way. Now i understand the need for a metal heatsink.

YES, good point ... so better not to exaggerate with resin impregnation to make the thing IP69!!!
Here below:
Picture 1 shows Voltage and Frequency at no-load conditions at 20 km/h on a 28" wheel.
Picture 2 shows Voltage and Frequency on a 12 Ohm resistor at 20 km/h on a 28" wheel.
Below data are referred to Shimano DH-3D32-QR hub dynamo.

6V is the real-life voltage once you apply a load, there is no point in testing 20V, 40V, 60V which indicates there is no load attached.

As the pdf shows, the testing begins at 500Hz. This value was chosen because the The Plug 3 cycles off at 250Hz. The D1 will work at a lower value but I wanted to keep the test equal for all devices if possible.

In other words, this test is not a quantative test of a converters output at a given speed, but rather when there is enough power supplied to provide a 500mA output, what is the efficiency transfer of the converter.

IT DEPENDS ON THE LOAD, OBVIOUSLY !!!

Just for your information:

- Picture 1 shows Voltage and Frequency at no-load conditions at 20 km/h on a 28" wheel.
- Picture 2 shows Voltage and Frequency on a 12 Ohm resistor at 20 km/h on a 28" wheel.
- Picture 3 shows Voltage and Frequency on a 40 Ohm resistor at 20 km/h on a 28" wheel.

All below data are referred to Shimano DH-3D32-QR hub dynamo.
As you can see all values are referred to 20 km/h, if you go at 40 km/h then frequency will double and voltage will tend to increase significantly.
Cheers.

You limit to 21V, so you will convert additional energy into heat (unloaded/partial loaded case). A lot of heat at faster speeds, which explains why you need the metal heat sink while most of the others work fine without. It also severely limits the lifetime of all components within the case. Elkos lose half of their lifetime with every 10°K increase. Your 25-year-stuff can and will die faster then expected.



The Plug was designed to work with hubdynamo, not an amplifier. I guess that triggers various safeguards. Looking at a real signal and comparing to the amplifier output might show why.



My bike can accelerate with ~9.81 m/s² if i drop it of a cliff. I would not take that as a test of my ability to it accelerate on a flat road.

I use 10ohm/ 0.5A indicative of a typical smartphone.

There are no electrolytic capacitors inside the case. The D1 design requires the 21V limit, which isn't as efficient at higher speeds without a load attached BUT offers significant efficiency gain at lower speed and/or with a suitable load. That is the trade off, and one I was happy to make because the majority of tourers and commuters are not doing 35kph+ on a constant basis and they tend to buy dynamo hubs to power things. I've already done the alternatives; load dependant darlington shunt, and high voltage PWM (crap at low voltage, low output, less efficiency - Igaro D1 PWM is 95%).

On heat, here's how much it generates from an actual user (see last post):

https://www.lfgss.com/conversations/289960/

The Plug monitors the output voltage and cuts off if it drops. It does not have the capacitance or efficiency to continue over the transients hence it's poor performance at low speed. The ability to function at differing speeds is outside the scope of my pdf test.

@acharnley

I'm not totally sure whether you're joking or not!
In your pdf you say "For this test mains frequency (50Hz) is too low to guarantee 500mA".
Can you explain?
I'm testing dozens of converters (e.g. e-werk, usb-werk, Luxos-U, etc.) and believe me I've no problems to get 500mA at 34Hz (i.e. 20km/h on a 28" wheel).

The 500mA must stay within USB spec (4.75v). The D1 can't do it at 50Hz. The Plug 3 can't do it at 250Hz. I can't say for other units.

Test with a 6V transformer and a high VA rating. 10ohm across the converter. Mains is 50Hz in Europe.

Use a pure sine wave rather than test results based upon a specific dynamo design.

I know that mains is 50Hz in Europe, but unfortunately a standard hub dynamo delivers roughly 34Hz at 20km/h, twice at 40 km/h, three times that frequency at 60 km/h ... and so on so forth. Furthermore I'm a bit afraid that using a "pure sine wave" as you're doing with your lab generator is a sort of a fancy approach not reflecting at all a real dynamo output that, as far as I can see, isn't a perfect sinusoidal shape at all. In conclusion ... I suspect that your tests are simply an overall nonsense, sorry for that.

You might as well remind me how I and the rest of the world go about calculating efficiency again? What's the equation?

Exactly the one you've been using: W(out)/W(in).
The problem is that your fake signal generator is NOT a dynamo, please repeat all your tests with real dynamos and related real frequencies. Cheers.

Well at least we've cleared up that your method is unable to demonstrate efficiency.

I'd be more than happy to carry out a similar test to your own, but the hub would be different and different wheel size so results would be incomparable.

Since we've agreed that my method does calculate true efficiency by the process of Math, you are in a better position to produce universal results.

Please repeat all your tests to conform to the recognized efficiency equation rather than for a specific dynamo hub.

Dear Acharnley please don't be silly, Math???
Sorry my dear but efficiency is just Wout/Win!!
But it's OK, you won, therefore I finally give-up and prefer to get out of this totally useless discussion.
Cheers.

It only became total useless once you jumped on it, ignoring the original subject matter.

Let's talk about a different kind of efficiency: this thread is on page one of Google.de results about your loader. It contains a link to a thread were you basically offer free stuff for positive reviews. You demonstrate a very interesting method of communication and little understanding how electricity generation works. This forum has several commercial, tech-savvy participants (manfacturing and dealers).

Good luck marketing this one away.

On the technical side: your amplifier is probably not a 4 quarant model (high VA and ~kHz with 4q does not come cheap), meaning your results will depend strongly on the amplifier. You cannot even replicate the same input current for 2 loaders. And it is not related at all to hub dynamos. Phi will be way off, no matter which amplifier you use.

" were you basically offer free stuff for positive reviews"

Please stay clear of defamatory comments. Nobody has ever been paid for a positive review nor has any review ever been pre-edited.

I'll exit this conversation now that it is becoming one of hate.

Because the construction of the loading device influence the output of the generator related to speed.

If one device get a input of 3W at 20 km/h and have a efficiency of 80 percent and the other device get a input of 5W at 20 km/h and have a efficiency of 75 percent, than the second device is the better device, in spite of lower efficiency.

The same using rechargeable battery. It may lower efficiency. But if your navigation device battery is full and the loading device produce more energy than the navigation device needs, you can save energy for the times, when the loading device produce too little energy.

So with a rechargeable battery and lower efficiency you can produce more useable energy than without a rechargeable battery and higher efficiency.

Very good points, thank you !!

That would help, but not totally solve the problem. He measures W(in) using a multimeter, ignoring the power factor.

He might hit a harmonic at 500Hz and has no chance to truly measure it using his equipment. So reported W(in) might be bogus, the system boundary is very unfortunate/irrelevant and the current source is unrelated to the real world application.

I understand startups are looking for a fortunate testcase for promotion. I even think giving out samples for reviews is ok if the review includes that information. But this efficiency claim is way too far off. He might have a case promoting the form factor (it looks tiny) or the support-local-guys route. IP69 might be a seller, if the resin can really resist a high pressure washer and he does something about the USB port (IP67 USB ports exist. IP67 only while closed, of course...).

You could of course implement the minimal loader design and put it into a fancy case. I'm pretty sure it would be the most ecofriendly system around from the raw materials point of view. And very, very cheap to produce.

I'm quite happy to replicate the wheel test and publish these results. I only have a Shimano 3N80 (XT) hub, the 3N30 is obsolete.

What was used for the variable resistive load?

... ahhh, I knew very well the story of harmonic distorsion and the fact that to make reliable mesurements he was supposed to use a power analyzer and not just a multimenter, but intentionally I preferred to ignore this aspect just for not complicate too much an already very critical discussion.
Here below the "scrappy sinewave" of the dynamo output when you connect it to an e-werk.

I'm done with arguing this.

I have sent a request to https://fahrradzukunft.de

I'm confident the Igaro D1 has greater efficiency and thus will offer greater output at any given speed, but they can test it and we'll see.

Do you have a wattmeter? Those solve several problems in one go and will give you power in and power out, DC and AC.

You are expecting a maximum output of roughly 20W at 5V. I would use 2, maybe more heavy heating 10 Ohm resistors and do several combinations to get the maximal power. One testrun in parallel, one serial, one with just one resistor. Thick cables, proper soldering,... tedious work, but doable. And easily comparable results.

Resistors, even those made out of Konstantan, drift with temperature, sometimes as a function of the material, sometimes due to thermoelectric effects. Using just one multimeter, that drift can influence the result as the resistor heats up. A really big resistor with a large cooling area does not heat up that much from 3-5-20W and should be safe. Ridiculously big ones are available and cost less then a proper second multimeter.

With a wattmeter (or if you only do output and assume pure DC: 2 multimeter) a series of small 20W resistors should be enough. They do heat up, so put them somewhere safe. Or use variable, manual resistors. (I would pick a ~100W model, 2 multimeter minimum)

Electronic loads would be total overkill, but offer the most flexible setup. Pick one that can do MPP-tracking, it saves a lot of work.

Are you sure that the model you've linked is ok ? from its instructions manual, chapter#2 I read:
#2. DESCRIPTION OF THE INSTRUMENT
- The measurement range concerning the fundamental frequency is 40 to 70 Hz.
- Voltage/Current: Sinusoidal signal (THD < 0.1%)
- Power: Sinusoidal signal, PF = 1, Frequency 50 Hz, Measuring range 10.00 W...999.9 W

NOTES:
- at 20 km/h you might expect 32-36 Hz
- expected THD is well above 20%
- Power measuring range has a minimum starting from 10W

It is using a internal 2kHz sampling and calculates based on the instantaneous values. It is not the high end option, but it did work reasonably well here (PWM for heating, 100Hz, 25 - 500W). It does not really need a low THD (Current (THD = 40%), typical error 0,2%) and it does not stop working completely outside the usual 40 - 70Hz window. Just don't trust it at 200Hz. But i never tested it at lower power ...

The better option (Fluke) is officially limited to the same frequency rage. But that one does work at higher frequencies.

Digital 2 channel oscilloscope is the better option, but more complex in use. I used one to check the cheaper wattmeter. You don't really need the wattmeter if a oscilloscope is available ...

The pdf I used earlier explains the resistor type and time, 5ohm 10W ceramic. Not kept on long enough for heat to be an issue.

A wattmeter/voltmeter+ampmeter can only measure within good accuracy a pure sin wave - at least, I don't have a model that can sample wave energy and average it. The signal was read using a digital oscilloscope to ensure the amp wasn't overloading and distorting the signal. The amp I use to boost the signal generator is a class A/B 100W. I also use a class D 100W and get the same figures.

I hope your man isn't using the built in li-ions to skew the output results as the German translation is not clear. This would be very unfair.

I'm presently using FLUKE 43 (not 43B) but my limit seems to be the current clamp that starts from 500A (url) ... too much I think !!

Check voltage and current, at the same time if possible. Class AB and D give similar results if the output lowpass filter on the class D matches the system well. I can't really comment on that for your system.



That's why you test over longer times and cycle the batteries completely...

It is possible to display the current power flow (batteries, consumer, generator) with a smartphone app to check for obvious test design problems.

Hey, during the last days I have read this topic with great interest. My point of view ist the one from a potential buyer of a Dynamo to USB-Adapter within the next year.
I would like to add few thought, but not to offend or argue against you or your product, but to explain why people here behave how they behave... and maybe even give you a hint how to improve your product and specially your "marketing" But please keep in mind that my technical knowledge for this topic is limited.

1)People here in this Forum are researching and developing since ages how to use the power of the dynamos for different solutions. Here a random old thread topic to show you since how long this topic is present here. Since then the knowledge and experience have expand, and later several more ore less commercial solutions (most of them bad, some even usable, a few quite good) have come up and most of the vanished since then. But people here still used to build there "own" stuff to satisfy the specific needs of different travellers.
To find ways to compare this totally different solutions for different tasks and needs is even more complicated. The Forumslader is just one of a few dozen solutions that has been developed, tested and compared here. True, the Forumslader is the most famous on, because it meets the needs of most of the travellers here (and have a few extra gimmicks like an extra 12V output, speedometer, odometer bluetoot, Android-App etc), but there are many different other solutions that work quite good to.
Now, you came across claiming you found the estimative solution, the philosopher's stone, people here even may "find it's electrically impossible using today's technology to get better efficiency than the D1 !!!!!!111!!!" (yes I added the exclamation marks to your quote) you may understand that people now a at least a bit sceptical. So people ask questions about it and how your test are done.
They even try to show your what kind of testing are done with other solutions, so you can do the same to have some comparable solutions, or just sent your device there so it can be tested with their experimental Setup. But first you doubt the test setting and repeat that your solution _must_ be the best of all and "blow your skirt", "England -v- Germany,Match accepted!" etc....
People here a bit allergic to such kind of exaggerations and marketing phrasing.
These kind of marketing has often be used to push bad products, so people become even more sceptical when you use even more aggressive marketing blabla.

so at the end


This was the best (and I think the only) way to show what (or what not) is your device
capable of. I (and many others) will certainly notice how your device will perform well compare to other solutions. Just keep in mind the Fahrradzukunft people do this as a hobby in there free time and wont get paid for this. This means that it actually may take quite a while if they decide to test it.

Otherwise you may still find a few people here that are still not annoyed (annoyed, pissed overstrained - all this word are to "hard" to describe what I mean -Im still searching for the right word)*by you in the who have the knowledge and the good reputation to test your device and will write a report about it when you ask them, and send you back your device afterwards...

*yes people here in germany (and also specially in this forum) can be easily offended if you hit the right spots, you already found a few

Btw: the fact that you only have a reseller from GB is not a Dealbreaker for german buyers- at least while GB is still in the EU. 10€ Shipping could be better but is still ok. People here actually like small one person solutions once they have been proven the be working and provide solutions that the "big company’s" don't provide (examples: Rohloff, Grobox, Reisegabel, Forumslader, ...)

So far, as very well suggested above, sometimes “EFFICIENCY” is not a top priority. What is most important is indeed the effective power that a certain AC/DC converter can draw from the AC side (generator) of a system and deliver to the DC side (load) at a certain speed.
To make it clear once again: “if one device gets an input of 3.0 W at 20 km/h and has an efficiency of 80% and the other device gets a input of 3.5 W at 20 km/h and has an efficiency of 75%, than the second device is the better device, in spite of its lower efficiency”.
To make evaluations on how good an AC/DC is, I personally do not even need very sophisticated laboratory instruments since I make all relevant measurements directly on DC side.
To do that I use a real generator, a real AC/DC converter (the one under test) and an adjustable ohmic load made-up of calibrated ceramic resistors.
The wheel/generator speed is controlled and finely tuned via an asynchronous motor powered by a 3-phase inverter. At this point the test method is extremely simple: I adjust (sink) the load till to get the maximum transferred DC power to the load taking care of course that the voltage doesn’t go below a certain “low limit”.
For instance for usb 5V voltage I’d set this limit to 4.75V.
The results seem to be pretty reliable so far.
The basic estimate criteria would be that an AC/DC converter is as better as bigger is the amount of ACTIVE POWER that it will let to flow from the generator to the load.
The test system I use is THIS ONE, home made but pretty well performing.
Here below a couple of sample plots based on a Shimano DH-3D32-QR hub dynamo and an e-werk respectively set at 4.9V (1st plot) and 5.6V (2nd plot).
As you can see at 20 km/h it doesn’t seem to be able to transfer more that 2.75W: