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May 01, 2021, 02:19 PM
New to this whole thing...
Thread OP
Discussion

Help me diagnose this problem with Vgood 20A ESC?


I recently bought three 20A VGood ESCs from Aliexpress. They look like this:

https://www.banggood.com/VGOOD-20A-2...p-1422422.html
https://www.getfpv.com/v-good-rc-32-...-airplane.html
https://www.aliexpress.com/item/33000549616.html

These are supposed to be the same as the Turnigy Plush-32 ESCs, they have good ratings on Banggood, and were recommended by another member of this forum.

They work fine on 2S, but on 3S at half throttle or so the motor starts to "stutter". (This is with a 2300kV motor, with an 1850kV motor the throttle needs to be higher.) I have the programming card and I played with motor timing, PWM frequency, enabling/disabling the brake, etc. and nothing seems to help.

Anyone have any ideas?

Here's a video: https://photos.app.goo.gl/M3qRGWgGp6xwMzWG7
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May 01, 2021, 06:15 PM
Space Coast USA
hoppy's Avatar
Happens with 2 different motors at about the same rpm? Happens with all 3 ESCS?
Anything in common to all set ups? That's where the fault may be.

Does it also occur with a prop on the motors?
May 02, 2021, 01:56 AM
New to this whole thing...
Thread OP
It happens on all three VGood ESCs, doesn't happen with my other ESCs on the same motors. I've now tried them with a 2400Kv motor, a couple of 2280Kv motors, and an 1850Kv motor, all of various dimensions. The "stuttering" seems to happen at about half throttle on a 3-cell battery, a bit more with the 1850Kv motor. Doesn't happen at all on a 2-cell, even at full throttle.

It still happens with a prop mounted, but the added rotational inertia makes it not as obvious. I doubt it's good for the motor or ESC though.
May 02, 2021, 03:57 AM
Entropy is happening!
Jim.Thompson's Avatar
Did you program your VGood ESC with the program card?
There may be some parameter or other that is not set correctly.

I have a 40 Amp VGood ESC and I bought the card to program it. It takes a bit of working out how to use it, but once you get it, it does the job instantly and well.

Jim.
May 02, 2021, 10:39 AM
Space Coast USA
hoppy's Avatar
So it's losing sync above a certain rpm.
Many posts on quads losing sync.
For instance: https://www.miniquadtestbench.com/br...sc-basics.html

Don't know if that is the problem or not.

Search of RCG for sync problems:
https://www.rcgroups.com/forums/sear...sync%20problem

From this post: Kind of sounds like yours. https://www.rcgroups.com/forums/show...0#post45604513

sync loss, try changing the ESC timing angle to a smaller number.
Last edited by hoppy; May 02, 2021 at 10:46 AM.
May 02, 2021, 11:56 AM
Space Coast USA
hoppy's Avatar
Article on ESC timing
https://www.radiocontrolinfo.com/tim...otor-and-escs/
May 02, 2021, 04:07 PM
Entropy is happening!
Jim.Thompson's Avatar
Quote:
Originally Posted by hoppy
So it's losing sync above a certain rpm.
...................................]
That was my uninformed guess. That is why I suggested the programming card to go through all the parameters.
May 02, 2021, 06:05 PM
Space Coast USA
hoppy's Avatar
My uninformed guess too.

It's interesting that one guy said reduce the angle to fix the problem and another guy said increase the angle tpo fix the problem...typical web advice.
May 03, 2021, 09:58 AM
New to this whole thing...
Thread OP
According to most of what I've read online the usual cure for sync loss is to *increase* timing. (Especially for outrunner motors.)

As I mentioned in the original post I do have the programming card and I've gone from the default 18 degrees up to 24 and 30 degrees as well as "auto" timing. I've also played with PWM frequency, startup power, and brake strength. Everything else is stock.

I'll try dropping the timing on the off chance it fixes things, but if it does I'll be shocked.
May 03, 2021, 04:27 PM
flyin' fool
goldguy's Avatar
It's a common problem and a simple fix, one I encountered exactly as described just yesterday. The right prop did the fix. He had too big a prop for the motor's KV and too much voltage.

Check the stats of your motors. Install the right prop and use the recommended voltage for that prop. Your problem is in fact the timing ............ in that it's being screwed up by too big a prop for the voltage.

https://www.rcgroups.com/forums/show...7&postcount=10
Last edited by goldguy; May 03, 2021 at 04:36 PM.
May 03, 2021, 05:56 PM
New to this whole thing...
Thread OP
The problem is not the prop size or voltage.

If you take a look at the video at https://photos.app.goo.gl/M3qRGWgGp6xwMzWG7 you can hear the stuttering (or whatever it is) when there's no prop and using a 3-cell battery.

The same motor works flawlessly on other ESCs, and three other motors showed similar problems on this ESC (as well as the other VGood ones).
May 05, 2021, 12:25 AM
flyin' fool
goldguy's Avatar
Quote:
Originally Posted by cbf123
Doesn't happen at all on a 2-cell, even at full throttle.
Seems voltage is a problem. What connectors are your using? Any cold solder joints?
May 05, 2021, 01:32 AM
New to this whole thing...
Thread OP
Quote:
Originally Posted by goldguy
Seems voltage is a problem. What connectors are your using? Any cold solder joints?
On an 1850Kv motor I have to advance the throttle more to see the problem than on the 2400Kv motor, so it actually seems related to motor RPM rather than voltage.

I'm using xt30 to the battery and 2mm bullet connectors to the motor. I was pretty careful about the solder joints and it seems weird that all three ESCs would fail in the same way.
May 05, 2021, 02:51 AM
Entropy is happening!
Jim.Thompson's Avatar

Motor current draw?


Quote:
Originally Posted by cbf123
.............................
I'm using xt30 to the battery and 2mm bullet connectors to the motor. .......................
We still don't know what current this set up is drawing. (Unless of course, I missed it: I just scanned back through the page and could not see a mention of it).
The current (unknown) might be approaching the limits for those little connectors.
A Power meter is an excellent investment if you are going to fly electric.
See the many posts from Ron, Scirroco and Hoppy on the subject.................just for starters.................

Edit:
My question @ post #4 still has not been answered!

Jim.
May 05, 2021, 08:55 AM
Registered User
Fourdan's Avatar
Quote:
Originally Posted by cbf123
I recently bought three 20A VGood ESCs from Aliexpress. They look like this:

https://www.banggood.com/VGOOD-20A-2...p-1422422.html
https://www.getfpv.com/v-good-rc-32-...-airplane.html
https://www.aliexpress.com/item/33000549616.html

These are supposed to be the same as the Turnigy Plush-32 ESCs, they have good ratings on Banggood, and were recommended by another member of this forum.

They work fine on 2S, but on 3S at half throttle or so the motor starts to "stutter". (This is with a 2300kV motor, with an 1850kV motor the throttle needs to be higher.) I have the programming card and I played with motor timing, PWM frequency, enabling/disabling the brake, etc. and nothing seems to help.

Anyone have any ideas?

Here's a video: https://photos.app.goo.gl/M3qRGWgGp6xwMzWG7
Hi CBF
What is your signal generator (throttle)? Servo-tester ppm ? or Radio receiver ? or ??
Louis
Latest blog entry: Scorpion Calc


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