My my boards came in today! Now I need to design a case. Fully functioning, gets rpm, current, and voltage and connects to an esc. No need for a motor analyser.


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So I have cobbled together some code using the internal comparator in the 328p chip and managed to get digital waves out of the bemf. Now my brain hurts because I learned how to use the port registers directly instead of doing digital read on pin yadda, yadda... Anyway, as you increase or decrease timing the digital waves correspond so that is something. I now need to reinvent my rpm counter using port registers and then setup a comparison between the bemf and the rpm. Attached is a pic that has the 3 bemf waves plus one rpm sensor output. The bottom waveform is the rpm sensor.

https://cimg0.ibsrv.net/gimg/www.rct...ea75c74c9d.png

Here is my initial design on implementing the telemetry sensor unit with the Load Master. So with this you don't need a motor analyser, just an esc to run it.

This is going to take about 15 hours to print on my small printer, so I would like feedback before I proceed. The front is open to allow for sensor harness connection, battery and esc wires and a usb to the arduino nano for possible updates.

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Mostly looks fine. I'd watch the clearance/tolerance in this area:
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Or the other side, the material looks pretty thin. Might need beefing up.

If I need to I guess I can. But this is the same as the current mount with the thinnest section being 2.75mm. So far there have not been issues. But, I suppose this could be a weak spot.

The top is a separate body as well, and will be mounted with screws. Maybe I should shave 0.5mm off the back side though just to make sure it doesn't bind. 15 hour print just for it to not align would be annoying...

I sometimes print smaller subsections of things like this to avoid disappointments ;)

Got too many printers now - I bought a chonky one to print fasterly and biggerly.

Hobbywing Tunalyser came in today.
Here is a photo with a Slot Machine 13.5 pulling almost 20 amps.

I will say the Tunalyser is a pretty nice piece of equipment.


https://cimg6.ibsrv.net/gimg/www.rct...490f1ab2d.jpeg

And here is a pic on an ESC running my telemetry unit.

The harness coming off the driven motor is for testing with timing. Doesn't need to be on the actual unit.

https://cimg8.ibsrv.net/gimg/www.rct...f8ad91e3e.jpeg

Update on Timing. I have proof of concept for measuring timing on one phase. I am attaching pic of a function generator setup to output 2 square waves at 303hz and phase shifted 45*. Then with the arduino I am measuring the phase shift on external interrupt pins. I am printing the output to the serial monitor for now, printed variables are frequency, RPM, and Timing.

https://cimg7.ibsrv.net/gimg/www.rct...f11ad7b166.jpg
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For a clean look, install your esc on top of the mount.
Hobbywing Just Stock pictured with Sanwa rx.


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Looks good! Did you make that coupler that connects the motors together yourself?

I did not. Machining metal is out of my scope. I really need someone who can do that...

Anyway, that is from Amazon, 3.17 - 3.17mm coupler.

https://www.amazon.com/dp/B08QFNDP3H...t_details&th=1

More testing with timing tonight. It is getting better, lol. Below are some pics that show a Slot Machine 13.5 @ 40* on the can and the readout from my code. Then @ 45* on the can with readout. Finally I put an R1 v21s 21.5 @40 on the can and the readout. Now R1 always read lower on the can by 4-5*. And my Motolyser confirms that. Now there are caveats... The pwm gets in the way of the bemf reading so I have only been able to read at full throttle. Anything less and all the readings are way off. I'm still working on it, lol. But this is progress!

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The SkyRC style analyers can only measure timing at full throttle as well. I'd say that's an acceptable limitation.

I took a turn trying something else this evening. I hooked my telemetry unit up to the MiniPro flywheel unit and ran a run using my telemetry unit. I had to tweak the code a bit to use 2 hall effect sensors instead of just one for RPM. I need to add the third, I'll work on that later. But for a first attempt I am pleased with the outcome. This is a Slot Machine 21.5. It compares pretty well to the MiniPro output with one big caveat. My numbers don't go above 65% efficiency. So there is that...

For anyone curious, I redirected serial output to a terminal monitor called RealTerm. I then took my readings and added them into excel and created formulas for Torque and Power. My initial sample rate is 10hz. I was having issues going above that due to my voltage and current averages interfering with the rpm. In order to proceed I am going to have to completely rewrite the code for faster sample rates. My original telemetry unit doesn't need to update faster than once per second, or 1 hz.

EDIT: Looks like I didn’t start the data quite right on the graph. I just need to grab the first values, so the power at 0 rpm is 0. Torque will also be zero, nature of the flywheel…

https://cimg0.ibsrv.net/gimg/www.rct...b6a46dbae7.png

65% peak efficiency sounds like it's in the right ballpark. Most dyno results of RC motors I've seen are in the 50-70 range.

I had a request to add "KV" to the readings. I took this chance to revise the software a bit. I also changed from reading the high low pulse for rpm to using hardware interrupts. Also I cleaned it up a bit to be able to run both my telemetry module and a motor analyzer in tandem with each other. Here are some pics of running the SkyRC unit with my telemetry module. I also am comparing to my 5.5 digit bench dmm to show that my telemetry unit is more accurate for voltage, and KV is dependent on voltage.

https://cimg7.ibsrv.net/gimg/www.rct...a848e445f2.jpg
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I had a motolyser shootout last night and tonight. I took an R1 21.5 and a Trinity 13.5 and ran each motor at 30, 35, 40, 45, 50 degrees timing. I ran each of these on the SkyRC, Tunalyzer, Motolyser, and my telemetry unit. I also ran each test unloaded and then loaded with my Load Master using the 2 ohm resistor bank. This was interesting, and took absolutely forever... my conclusions are that the readings are all over the place, lol.

So caveats:
The Hobbywing Tunalyzer and the Trinity Motolyser both use 7.4v for the test voltage. To try to get close to the same on each test, I used my variable voltage power supply as a power source dialed to 7.75v. So there is a slight difference with the SkyRC and my unit for voltage.

Also, with the 13.5 on my telemetry unit with an esc, at 30* timing and unloaded, the current is actually higher than at 35*. I spent a good amount of time re testing and verifying this. I also ran my telemetry unit in tandem to make sure it was reading correctly. When using a analyser to drive the motor, it looks good. But when using an esc this behavior pops up. I got nothing... I tried both a Hobbywing Juststock, and an XR10 pro gen 1. Unfortunately I can't exactly test a motorlyser and an esc in tandem...

Anyway, instead of putting a ton of pics on here, this time I am just linking to my github repository. https://github.com/trilerian/Dyno-Results

EDIT:
Added graphs with Current vs KV.

Case redesigns to allow for a little cooling of the motors.


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I thought I read, in an earlier post, that the Tunalyser will only go to 12 amps. Here you're getting 18amps. How high will the Tunalyser go?

Hobbywing says 12 amps. Mine goes up to about 20 before the cutoff. But it may vary between units.

Dude!!!
This is awesome. I played around with it just a little, and i already see the great benefits of having one. I really love how the motor snaps right in without having to loosen anything up. I'm not sure if it was meant to be that way, but it works like that What I love even more is being able to test motors without having to clip on alligator clips to the motor tabs. Now I don't have to worry about shorting out on the can.

Have you thought about taking this design and making motor stands for regular testing? I'm sure they would be a big hit due to not having to clip onto motor tabs. You can also do the same thing, as Trinity, and add a slide out tray to store rotors. They charge $14 and it is just a cradle with a slide out drawer.

Yeah, I can’t stand the alligator clips. Which definitely adds to the Load Master’s usability. I thought about making a single mount, but I need to get my website up and going first. Once that is done I will start making 3d printed stuff. Although I will say my interest is more in the electronic side, there are already quite a few makers of 3d printed goodies. But some of that stuff is just good to have available.

Just came off the printer.


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That's what I'm talking about!!!

Tonight, I took a break from my Rotor Master and picked back up trying to figure out measuring motor timing. I haven’t forgot about this project, but progress is slow… Hopefully though, I have made a breakthrough. After some pondering about the issue, I finally decided to put look at the signal for the virtual common created by the resistors tying the 3 phases together. I expected this to be a more or less stable voltage that was ½ the bemf voltage on the phases. But that is not the case. The duty cycle (pwm frequency) plagues the common neutral just as much as it does the bemf signals, also the neutral is a trap wave as well. So using a comparator on the crossings of 2 inverting signals, both cut with pwm, no wonder I was having issues. A while back a made a board that had a few sensors on it and some resistor divider networks so when I wanted to “tinker” I could use it and run wires to an Arduino from it. So I broke that out, along with the SkyRC analyzer, and my Arduino nano with a bread board and a bunch more resistors.



So here was my thought for the evening, instead of using the virtual common created by the phase wires, I would use the power source with a couple of voltage dividers. My setup is using voltage dividers on the bemf to start, so I used the same divider on my battery then another voltage divider configured to half that again. Thus in theory giving me a stable output around 1.65v. I would then use this as my non inverting signal for the analog comparator in the Arudino.



Now, the second issue to overcome. PWM on the bemf signal. Sure, full duty cycle gets you the signal with no pwm, but I really want to get to a point where I can measure timing under the full duty cycle. Tonight I decided to try a low pass filter on the bemf signal. I tried a few different cutoff frequencies and watched the response of the signal on my scope. What I came to realize, was making the cutoff too low made the rise time on the signal too long. What this does is ultimately push the “zero crossing” out a bit. With that in mind I had to make a filter with a cutoff of approximately 30khz. Which isn’t low enough but it is a start. The experiment was a partial success. The filter did attenuate the pwm signal enough that I was able to get timing at about 90% duty cycle.

There are still some tweaks to work out, one being the voltage used as my non inverting signal is off slightly which causes some variance, another is to get a good filter value that doesn't mess the results up. I think I am going to go back to an external comparator as well to take that load off the Arduino. But in the end, I think this is going to need a faster mcu.



Here are some photos of tonight's work.
In the scope pics,
The yellow signal is the signal from the hall sensor on phase A.
The blue signal is the output from the comparator on my Arduino
The pink signal is the signal of the bemf after going through a voltage divider and the low pass filter
The green signal is the stable voltage that I am comparing the bemf to for the zero cross. I adjusted the green signal to be about half way through the pink for a visual reference.

The first two pics show the SkyRc output compared to my scope. This is appx 80% duty cycle and you can see the chopped pink signal touching the green signal still, the output of the comparator is show with the blue square wave. Timing can not be read here because there are too many crossings.



https://cimg2.ibsrv.net/gimg/www.rct...2fb0104bcf.jpg
Crazy setup!

https://cimg2.ibsrv.net/gimg/www.rct...d931501c34.png



The next pic show approximately 90% duty cycle. See how the chopped pink signal is no longer touching the green line, thus giving a good zero crossing. Notice the blue signal looks like a good square wave and see the output from the arduino is getting timing results.

https://cimg7.ibsrv.net/gimg/www.rct...c7d886d4a5.jpg
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And finally, 100% duty cycle. But I had gotten to this point before...


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So, do you have a video on properly using this and/or what to look for? I'm about to run mine and do some motor comparisons. I have some questions, that I'm pretty sure I already know the answers to, but I want to make sure I get it right.
Here are my questions:

• What should I adjust the time to, on each motor, to make sure they are faire tests? Do i set the timing between 5 and 6 amps, unloaded?
• What exactly do I look for while comparing them?
• What would depict one motor being better than the other.

Like I mentioned, I pretty sure I know the answers to this, but I don't want to miss something that I should have been looking for and I show an even and fare comparison between the motors.

Here is a youtube video

https://www.youtube.com/watch?v=GtC89i8M8hY

The same video is embedded on my site which is in my signature.

Killer info as usual. Awesome video.

If I'm using a 17.5 drive motor, is it okay to use a 17.5 slave motor?

So,
Lets say I'm testing 2 motors. I adjust the timing so each have an amp draw of about 5amps, unloaded. Loaded, motor-A draws 11 amps and motor-B draws 13 amps. Would that mean that motor-A has more torque?

No you can't make that assumption. Motor A might just be more efficient.

So motor A is the better motor?

If you are using the same slave motor for each. Then the motor that has a higher Kv with a lower amp draw will be a more efficient motor.
And yes, you can use a 17.5 as a slave when testing a 17.5. I would start with a slave motor of the same windings as the test motor before going to a higher wind motor as a slave.

Can't make that assumption either. To elaborate, motor A drawing 11 amps and motor B drawing 13 amps - but at what RPM? Using the same slave motor doesn't mean they're running at the same load, if they're running at different RPM.

Ok.
I finally finished testing those 5 motors on all of WMH Racing products. Some numbers were pretty surprising.

https://youtu.be/1x1TKn_GJKM

It was requested to make a tips video for basic use and there have been a couple of case iterations that are gone over in this video. Time stamps are in the description. Warning, this is a long video and I have not yet invested anytime in learning how to edit videos.

https://www.youtube.com/watch?v=oPLceou76s8&t=1258s

You know...
What puzzled me, about the test, is the Fantom motor not being able to turn, while under a load, at low power. I checked the battery voltage, the contacts, etc... it's just weird that the motor appeared to have no low end torque.

I was demoing the unit for someone who gave me a slot machine that wasn't performing, he said this motor is bad. Sure enough with the Tunalyzer when it hit the 3rd rpm switch, the motor didn't do anything. Gave it a helping hand and it spun up.