• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

Brushless motor stuttering on throttle up

#1
I tried digging through various forums trying to find an answer for this but I have yet to find anyone with the exact same set of symptoms as me.

The motor in question is a Turnigy Propdrive V2 2826 spinning a 9X6 prop.

What's happening is as follows:

Transmitter is turned on, plane electronics are powered up by plugging in the battery, and the motor makes its preflight beeps. If I start to throttle up on the Tx to quickly the motor will start to twitch about, flinging the propeller randomly left and right without ever making a full rotation. If throttle is applied very slowly then the prop will gradually spool up and then once everything is moving I'm able to make quick throttle adjustments without any problems. It's just the initial start from a standstill where the motor has to overcome the zero kinetic energy of the prop and get it spinning that causes it to start twitching.

The batteries I'm testing with are all charged and almost brand new so the ESC isn't in low voltage protection mode. I've also tried dorking with the End point adjustments in the TX to make sure it wasn't set to anything weird. And I've gone through and tested all the connections between the ESC and Motor, which are all good. Again, the motor behaves fine when already spinning. The issue is only with the initial torque required to spin the prop.

Any help would be appreciated. I've drawing a blank on what the problem could be. If I need to buy a new motor, so be it. I just want to know if anyone else has seen this.

Thanks
 

FastCrash45

Well-known member
#3
I tried digging through various forums trying to find an answer for this but I have yet to find anyone with the exact same set of symptoms as me.

The motor in question is a Turnigy Propdrive V2 2826 spinning a 9X6 prop.

What's happening is as follows:

Transmitter is turned on, plane electronics are powered up by plugging in the battery, and the motor makes its preflight beeps. If I start to throttle up on the Tx to quickly the motor will start to twitch about, flinging the propeller randomly left and right without ever making a full rotation. If throttle is applied very slowly then the prop will gradually spool up and then once everything is moving I'm able to make quick throttle adjustments without any problems. It's just the initial start from a standstill where the motor has to overcome the zero kinetic energy of the prop and get it spinning that causes it to start twitching.

The batteries I'm testing with are all charged and almost brand new so the ESC isn't in low voltage protection mode. I've also tried dorking with the End point adjustments in the TX to make sure it wasn't set to anything weird. And I've gone through and tested all the connections between the ESC and Motor, which are all good. Again, the motor behaves fine when already spinning. The issue is only with the initial torque required to spin the prop.

Any help would be appreciated. I've drawing a blank on what the problem could be. If I need to buy a new motor, so be it. I just want to know if anyone else has seen this.

Thanks
I just had something similar and it was the timing being set to high. I loaded the factory defaults and rechecked and the problem disappeared. I went through all the programming and rechecked each setting. Once I was in the timing area I was able to recreate the problem by setting the timing to high. That was the only setting the problem showed up at. It was fine at low and normal. Hope this helped.
 

quorneng

Well-known member
#4
Timing set too high. this would suppose you adjusted it is some way. I have yet to come across an ESC where it did not work as delivered.
As suggested the same symptoms can result from a poor connection. The initial short pulse given by the ESC to get the motor turning is in effect full power so there is a considerable torque shake. This can trigger a loose connection. At that point the ESC cannot 'read' when to send the next correct pulse so it does the start up pulse again.
The only way to be sure would be to try the ESC with another motor that is known to work.
This sort of testing by substitution is vital to trace odd faults and is why I always have a spare battery, ESC, motor and servo tester "on the bench".
 
#5
Thanks for the advice. I probably should have mentioned that I haven't made any changes to the ESC out of the box so its still at its default timing which I believe is set to low. ESC is a trunigy plush 30A for what thats worth. And this whole setup worked fine a few days ago. I'll check the continuity across all the wires down to the coil of the motor (previously I only check the connection across the bullet plugs between the ESC and Motor).

I've only got the one motor for now (just getting into the hobby) so I don't have a way to cross check anything for troubleshooting otherwise i would have done that before I even thought about posting on here.
 

quorneng

Well-known member
#6
If it worked fine earlier then obviously something has changed. If it is a connection fault that only appears as the motor starts it will not be at all easy to find. It could even be inside the motor itself.

All you can do is to really wiggle the motor and ESC wires about as you open the throttle (with the prop off) to see if it makes any difference.

If you can't identify a connection fault you may have to consider buying a replacement but which, ESC or motor?
Without the right test gear you can only guess and hope!
 
#7
I have a park 370 that I overheated. After I let it cool down, giving throttle would produce a twitch. I was never able to get it to spin, still have to dissect it 😋
 
#9
Figured out what the problem was if anyone wants closure. I ended up redoing the connections between the ESC and the motor and discovered that one of the solder joints was only holding onto the insulator of the wire and was only making contact if it was bent in a specific way. Apparently when I was testing the connection it was making contact. But in order to fit everything in the plane the wires had to make a few bends around the firewall and that caused the connection to break. Rather than reinstall the bullet connectors I re tinned the wires and used a few heat shrink crimp on butt end connectors to fuse the motor and ESC together. Now she runs like a champ.

Thanks for the help everyone. Turns out I just need to reevaluate my soldering abilities.
 

Mad_Mechanic

Well-known member
#11
As @Bricks suggested, you might also want to calibrate/re-calibrate the throttle channel on that ESC.

I was just setting up one of those exact ESCs over the weekend and I had a pretty big deadband from 0-20% on the throttle stick. Figured out I needed to calibrate the throttle on the ESC. I know this isn't the symptom you originally posted, but it's worth checking if you haven't already done the the ESC throttle calibration.

Glad to hear you found the issue, I was going to suggest motor wiring issues if you hadn't found the problem.
 
#13
I'll try and grab a programming card on my next order from hobby king. Until then I set the end points for the throttle in my transmitter under my specific model profile. So now the motor is right on the edge of spinning at zero stick input. I also tuned the top end so the ESC doesn't cut out at half throttle position anymore.

Is there a benefit to tuning within the ESC Vs the Tx? or is it just preference?
 

Mad_Mechanic

Well-known member
#14
I'll try and grab a programming card on my next order from hobby king. Until then I set the end points for the throttle in my transmitter under my specific model profile. So now the motor is right on the edge of spinning at zero stick input. I also tuned the top end so the ESC doesn't cut out at half throttle position anymore.

Is there a benefit to tuning within the ESC Vs the Tx? or is it just preference?
I guess you could say it's a preference but I also like that I don't have to mess with end points or sub-trims in the radio right at the start.

It's a really simple process to calibrate the ESC to match your Tx, particularly for the Plush 30A. All you have to do are the following steps:

1 - Connect the motor to the esc but DO NOT mount a prop! Basically, the motor is there to be a tone generator/speaker. Connect the ESC to the throttle channel of an Rx that is bound to your Transmitter. DO NOT connect the battery yet.

2 - Turn on your transmitter and with throttle end points/trims/sub-trims set to default, put your throttle stick all the way up (max)

3 - Plug your battery into the ESC and wait about 2 seconds, you should hear 2 short beeps/tones.

4 - Bring your throttle stick all the way done to 'zero', the esc should now give you normal start-up tones (cell count beeps, etc.)

That's it!

I do recommend the Turnigy programming card for any other settings you need to change, but calibrating the throttle is the only thing that cannot be done with the programming card. It can only be done with the above described process.

Once I did those steps (which are buried in the 'instruction manual' for the ESC), I had maybe a 3% deadband for the throttle and I was getting full range of throttle.
 

L Edge

Well-known member
#15
Had similiar problem, did you check the 3 wires and connections from ESC going to the motor? Way to check that is (remove prop for safety before connecting battery), move the throttle up slightly,and wiggle the three wire connections and if that is the problem, you will know right away. One time, found (after a crash) one of the wires soldered at motor ripped off.