Motor not starting smoothly

[Graham Davies 3]

Hi,

 

I have a generic Chinese 100A ESC that I intend to use to control a 5065 320kv motor. Again, a generic Chinese product.

 

I can't get it to start the motor correctly. As the throttle is opened, the motor judders without rotating. This continues until about half throttle, then the motor starts, and throttles OK. All is fine unless the motor is allowed to stop, and then starting results in the same problem.

 

I have tried pretty much every parameter in the set up, and it makes very little, if any difference. 

 

I haven't checked if there's anything silly on the TX (a Radiomaster TX16S), but is there anything obvious I should check? Or is the ESC Donald Ducked?

 

Graham

[Alan Hilton]

Sounds like the esc is cream krackered try another one 

[Outrunner]

Have you checked the esc to motor connections? I've had a similar problem a couple of times and turned out to be duff joins in the esc/motor connectors being held together mainly with heat shrink.

[Andy Stephenson]

Bad or non-existent solder joints covered by heatshrink sleeve are fairly common on Chinese batteries.

[Graham Bowers]

Think I'd be paring it right back and beginning with the motor, esc, battery and servo tester.

 

Check all connections as others have said, then fault finding by substituting battery and esc.

Edited December 17, 2023 by Graham Bowers

[Graham Davies 3]

Thanks all.

 

Connections are fine; made them myself and double checked them.

 

Tried 2 other motors, same problem, more or less.

 

Tried the same motor with a different ESC, ran perfectly.

 

So looks like the ESC is either rogered, or set up incorrectly.

 

What parameters would you start with?

 

Graham

[Andy Stephenson]

It may be the timing or the frequency that are wrong for the motor, see what reprogramming the ESC can achieve.

[Graham Davies 3]

I had tried that Andy. It seemed the most likely cause to me. I'll have another go tomorrow.

[Graham Bowers]

20 minutes ago, Graham Davies 3 said:

Thanks all.

 

Connections are fine; made them myself and double checked them.

 

Tried 2 other motors, same problem, more or less.

 

Tried the same motor with a different ESC, ran perfectly.

 

So looks like the ESC is either rogered, or set up incorrectly.

 

What parameters would you start with?

 

Graham

Depending on what documentation you have, I'd take the "restore to factory settings" path. I'm not experienced enough on this subject to advise on specific parameters.

[Denis Watkins]

Timing

As suggested above

Alter the timing

[Engine Doctor]

Have you checked the motor to esc bullet connectors. I had a motor with same / similar problem and found that one of the bullet typ connectors was not conducting very well where the spring grips the male plug. 

[Cuban8]

Try a smaller prop? - had a setup that would sometimes stutter on start up, but when I clipped the prop on a duff landing and replaced it with a slightly smaller prop the issue went away. With a 100A ESC you must be running a fairly large prop I'd have thought, so it's worth a try before dumping the ESC. Does it run OK on no load? Can you open up the ESC and check the manufacturer's solder connections?

 

[PatMc]

Do the ESC instructions advise calibrating to the Tx ? Even if they don't there's nothing to lose by trying this anyway.

 

To check the ESC/motor connectors without removing the heatshrink - try running the motor for 10 - 20 secs then feel if any of the 3 connectors are hot. If so that will point to a high resistance/duff solder joint. 

[Graham Davies 3]

Thanks Gents,

 

It's not the prop! So far, none has been fitted. Safety first and all that...

 

99% certain the connections are good. I solder my own, and whilst I'm far from infallible, I do take care to check my work. It's not at the motor side, because the fault follows to a different motor.

 

I contacted the seller who also question calibrating to the TX. I re-did this, no change.

 

I have asked how to do a full factory reset, just in case something is corrupted and not responding to set up information...

 

We'll see what happens

 

Graham

[Simon Chaddock]

If the motor runs OK on another ESC you really have to consider that there is something wrong with the ESC. Do you know if the "other" ESC have any special parameters set?

Unless it did you would have to consider the 100A ESC faulty.

100A ESC's are serious bits of kit. I would suggest contacting the seller for a refund/replacement.       

[Graham Davies 3]

Simon,

 

Yes, the spotlight is on the ESC. However, I want to rule out a parameter issue before I call foul. I have asked the supplier how to perform a factory reset (they replied saying "yes, do a factory reset and let us know what happens"...). If I do that, and changes of timing or throttle parameter yield no benefit, then it will indeed go back.

 

It's difficult to draw conclusions from a like for like test as I can't 'read' the parameters in the known-good ESC. If I could do this, I could match them on the duff one, and I'd know for sure.

 

Graham

[PatMc]

Graham, the fact that the motor will start at about half throttle suggests to me that at normal low start throttle setting not enough torque is being produced to move the rotor because the ESC isn't holding the power pulse long for the voltage to build up across the active motor coil winding.

You could try a normal start but spin the motor by hand whilst at a low throttle setting, the motor will probably run OK at this throttle setting (Do this either without a prop fitted or use a chicken stick) 

IMO, if it now runs at low speed it confirms that the ESC timings are fundamentally at fault.  

 

BTW the intended motor is very low KV which means it's windings will be relatively high inductance, are the other motors you've tried also low KV & what voltage batteries are you using ?

Edited December 19, 2023 by PatMc

[Graham Davies 3]

Hi All,

 

Thanks again for everyone's input. It really is greatly appreciated and helps form order out of confusion!

 

So, a little tooing and froing with the supplier has yielded absolutely nothing. Their suggestion as to how to conduct a factory reset (disconnect the power and leave for 5 minutes before re-entering program mode) is nothing short of ridiculous. In my attempts to find a reset instruction, I found the Skywing website, and it's very clear the ESC I have is nothing to do with Skywing! No real surprise, but they can have it back...

 

Graham

[Cuban8]

You've covered the usual causes of problems and have given quite a bit of time and effort to resolve the problem to no avail. Hopefully, the supplier will not mess you about regarding the return and go through the dance that many do to simply avoid having to take the loss on their balance sheet of a faulty item. They're not going to spend too much time with it and if they've imported it directly from China the chances of them getting any redress from the manufacturer is almost certainly zilch. BTW, have you had the item very long?

 

Edited December 20, 2023 by Cuban8

[Graham Davies 3]

Cuban8, yes, I've given the supplier plenty of opportunity to resolve the issue. We'll see where we get.

 

This is the issue with trying to save money; it can be expensive! I work in FE supply, and sell my products on the promise of removing the risk of poor quality to my customers. Sadly, this is the reality of buying direct from China; everything is great until it isn't. If you are prepared to lose the odd transaction, fill your boots. In this case, I am (although I expect I'll get some if not all of my money back), but if you pay peanuts, you generally get snoopy...

 

This ESC is only a month or so old. It was purchased for my current build and sat waiting the correct point in the build. I started testing a week or so before it was due to be fitted. It's now holding me up a bit, but there is no chance my 1/6 scale spitfire is going to be entrusted to a dubious ESC!

 

Graham

[Engine Doctor]

Hi Graham . On a decent model like the Spitfire your building I would definitely fit a separate power supply for radio and servos and use a Opto ESC with no BEC 

If your esc goes down you still have control of surfaces and retracts etc

[GaryW]

2 minutes ago, Engine Doctor said:

Hi Graham . On a decent model like the Spitfire your building I would definitely fit a separate power supply for radio and servos and use a Opto ESC with no BEC 

If your esc goes down you still have control of surfaces and retracts etc

 

I concur with Phil here,,, a run seperate rx battery in all my electric models as I have had an esc in the past take a total dump which caused the model to pile itself straight into the ground

[Graham Davies 3]

Thanks chaps.

 

I had already wired in a UBEC separate to the ESC anyway. I might however use an independent Radio and/ or retract battery as you suggest in order to stop jammed retracts from soaking up precious power. 

 

Supplier has agreed a refund, so no harm done here...

 

Graham