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May 06, 2021, 08:07 AM
New to this whole thing...
Thread OP
Jim.Thompson: I programmed with the programming card, yes. Other than timing, PWM frequency, and enabling/disabling the brake everything is set to the defaults.

There was no prop mounted for these tests, so it shouldn't be drawing much current at all. (The motor works fine connected to a Flycolor Flydragon Lite ESC so it seems mechanically and electrically sound.) I can run a current test to confirm. The 2mm bullet connectors are generally rated for 20A, which is the limit of the ESC.

Fourdan: The signal generator is a regular radio receiver. It works fine with the same motor on another ESC. Throttle endpoint calibration was done on both ESCs.
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May 06, 2021, 01:49 PM
Entropy is happening!
Jim.Thompson's Avatar
Quote:
Originally Posted by cbf123
Jim.Thompson: I programmed with the programming card, yes. Other than timing, PWM frequency, and enabling/disabling the brake everything is set to the defaults..................
OK. Thanks for the reply.

Quote:
There was no prop mounted for these tests, so it shouldn't be drawing much current at all. (The motor works fine connected to a Flycolor Flydragon Lite ESC so it seems mechanically and electrically sound.) I can run a current test to confirm. The 2mm bullet connectors are generally rated for 20A, which is the limit of the ESC...............
I cannot qualify this, but I would try it loaded. Do all the tests with a prop on, I mean.
Someone else more experienced with brushless motors might like to qualify (or dismiss) this?

Quote:
Fourdan: The signal generator is a regular radio receiver. ......................
What kind of "regular radio receiver"? (Brand, frequency, type etc.).

Jim.
May 06, 2021, 02:06 PM
New to this whole thing...
Thread OP
I ran a test to check the current draw. On a 3-cell battery with no prop mounted the current draw was less than 0.4A when it started to stutter/chirp/screech. With a 6x3 prop mounted it was under 1A.

Mounting the prop mutes the effect slightly due to rotational inertia, but it's still there. The same motor doesn't show the "stutter" effect on a different brand of ESC.

The RX was a FlySky FS-R6B which uses the AFHDS protocol on 2.4GHz. Switching out just the ESC to another brand makes everything work fine.
May 06, 2021, 04:44 PM
Space Coast USA
hoppy's Avatar
Quote:
I ran a test to check the current draw. On a 3-cell battery with no prop mounted the current draw was less than 0.4A when it started to stutter/chirp/screech. With a 6x3 prop mounted it was under 1A.
1A? Are you sure?
May 07, 2021, 05:09 AM
Registered User
Fourdan's Avatar
Quote:
Originally Posted by cbf123
I ran a test to check the current draw. On a 3-cell battery with no prop mounted the current draw was less than 0.4A when it started to stutter/chirp/screech. With a 6x3 prop mounted it was under 1A.

Mounting the prop mutes the effect slightly due to rotational inertia, but it's still there. The same motor doesn't show the "stutter" effect on a different brand of ESC.

The RX was a FlySky FS-R6B which uses the AFHDS protocol on 2.4GHz. Switching out just the ESC to another brand makes everything work fine.
Hi CBF
Normally a motor Kv around 2300-2400 rpm/V, with 3S LiPo and a GWS 6030DD (6x3) should consumes around 16A full thotlle
Louis
Latest blog entry: Scorpion Calc
May 07, 2021, 05:40 PM
New to this whole thing...
Thread OP
Hoppy: That's what the multimeter said, though a proper power meter might be more accurate.

Quote:
Originally Posted by Fourdan
Normally a motor Kv around 2300-2400 rpm/V, with 3S LiPo and a GWS 6030DD (6x3) should consumes around 16A full thotlle.
I was not at full throttle, I only advanced the throttle to the point where it started behaving abnormally (which was a bit under half travel on the throttle stick).

I did find it interesting that I could cause problems around half throttle on the 3-cell but full throttle on the 2-cell was fine.
May 07, 2021, 06:16 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
It looks like it's not just an accuracy problem, it would be veeeeeery inaccurate, something is wrong.

What is max. current range of your multimeter, 10A?
How did you wire your multimeter, and on what setting?
Make/type multimeter?

Excellent info about watt- & multi-meters, and how to use them. By RCG user vollrathd:
www.wattflyer.com/forums/attachment.php?attachmentid=117297

A very long clearance sale, originally 200+$, now literally peanuts:
Hyperion Emeter II wattmeter with local&remote logging, optical&electrical tach, servo tester - RCG

Careful!
(Always!) keep battery-/watt-/multi-meter wires short:
too long wires batteryside will kill ESC over time: precautions, solutions & workarounds - RCG[/LIST]

Vriendelijke groeten en wees voorzichtig, Ron
• Without a watt-meter you're in the dark ... until something starts to glow •
E-flight calculatorswatt-metersdiy motor tips&tricksCumulus MFC
May 10, 2021, 10:56 AM
New to this whole thing...
Thread OP
Yeah, 10A limit on the multimeter and the leads are too long. Was willing to risk damaging one of the ESCs that was acting up.

I've got a basic inline hobby power/current/voltage meter on the way to simplify things.

On the topic of keeping the wires short, these inline meters add 5-6" of length to the battery leads. Are people just living with that during the testing or are they actually adding more capacitance on the ESC during testing and then removing it for normal use?
May 10, 2021, 01:17 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
The long wires may have caused the misreading in current.

Vriendelijke groeten Ron
May 17, 2021, 09:21 PM
New to this whole thing...
Thread OP
Looks like my multimeter was accurate. I just redid the tests with an inline power meter. With a 3-cell battery at storage voltage and no propeller I got 0.35-0.4A at just under half throttle when the stuttering happens. With a Gemfan 6030 propeller it was drawing just under 1A when the stuttering happens. Right at half throttle it was 1.25A, and at full throttle it's just under 9A.

The videos of the no-prop tests are in this album: https://photos.app.goo.gl/ieQPk7aemKtv4fTH6

It's easier to hear the stuttering with good headphones, but you can see the motor "jerking" a bit in my hand when it stutters.

I included one video with mostly stock settings, one using the "EDF" motor type and manually specifying 3-cell, one with the default motor type but auto timing, and one successful one on a 2-cell battery. All had 24KHz PWM.

The motor in these videos is a Racerstar BR1806 2280Kv. I was also able to reproduce the problem with a Racerstar BR2304 1850Kv and a Racerstar BR2205 2300Kv as well as an unbranded 1806 2400Kv motor.
May 20, 2021, 10:52 AM
New to this whole thing...
Thread OP
The support guy over at VGood has said that based on his testing "normal" mode is only good for up to around 1500Kv and they recommend EDF mode for higher.

This is interesting, my other ESCs have no such problems.

On my VGood ESCs the EDF mode still has problems with 3-cell, but I'm supposed to be getting updated ESC firmware to test.
May 28, 2021, 05:53 PM
Registered User
Your situation sounds very similar to when I found out ESC's have RPM limits depending on how fast it can switch & the number of poles the motor has.
I discovered it when trying to put a mini-quad motor on a plane.
Some are higher than others, but I thought most newer ones were good for 2600kv or more.

Hopefully it is just a firmware glitch not allowing it to switch the magnetic fields as fast as it should.
Beware the screech though, it can let the smoke out of a motor..

The attached pdf comes from http://www.bavaria-direct.co.za
May 29, 2021, 04:17 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
If a motor can handle a 2magnet-pole motor up to M rpm (see specifications, max. electrical rpm), it can handle an P-pole motor a (2M/P) rpm. Enter P=2 to check
Why? Every time a magnetpole passes a statorpole it needs/uses/eats some processorcomputingtime, which is a limited resource.

Examples:
Motor max. e-rpm (2-pole rmp) is 140krpm.
Max. rpm for a 14magnetpole motor will be 20krpm, for a 10pole motor it will be 28krpm.

Prettig weekend en wees voorzichtig, Ron
• Without a watt-meter you're in the dark ... until something starts to glow •
E-flight calculatorswatt-metersdiy motor tips&tricksCumulus MFC
Last edited by Ron van Sommeren; May 29, 2021 at 04:25 AM.


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