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Author Topic: Brushless motor running rough above half throttle  (Read 2804 times)

Ultrarep

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Brushless motor running rough above half throttle
« on: May 01, 2016, 02:38:38 AM »

hello all
Following on from some sage advice from member here I now have all my hardware together and am up at this ugodly hour as I have a probless that I cant bottom out.


I have two new 2826-1000kv motors and HK50A ESC running on a 4S 2800 lipo.


All works ok but the motors both run rough over half throttle and seem to be holding back and not revving freely.


Anyone have any ideas on this? I have not soldered the other ESC yet so will try that tomorrow or today.
I have tried all the timing and other settings in the ESC and they make no dif on this issue.


Someone please help on this if you can.
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derekwarner

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Re: Brushless motor running rough above half throttle
« Reply #1 on: May 01, 2016, 03:57:54 AM »

ultra..............just looking, the WEB has an informative specification page for the motors, [& props] but lots of scary comments <*< for the ESC's, nor have you explained how you are controlling two ESC to the two motors via your transmitter/receiver

So a few simple thoughts

1. do you have access to a 3S battery to have a reduced voltage trial?
2. are both motors securely mounted in the hull?
3. are your tests loaded? ie., in the bath full of water?
4. you mention 1/2 throttle?......does this relate to ~~1/2 voltage or ~~1/2 speed?
5. you mention soldering connections >>:-(.......the specification talks about Bullet connectors...are these all OK?

I am sure a member competent in these BLACK arts will offer sound comment............ Derek
_______________________________________________________________________________
Specs:
Model: NTM Prop Drive Series 2826 1000kv
Kv: 1000rpm/v
Poles: 3
Motor Wind: 19T
Max current: 15A
Max Power: 176W @ 11.1V (3S) / 235W @ 15V (4S)
Shaft: 3mm
Weight: 54g
ESC: 20~30A
Cell count: 3s~4s Lipoly
Bolt holes: 16mm & 19mm
Bolt thread: M3
Connection: 3.5mm Bullet-connector

Prop Test Data:
9x4.7 - 11.1V / 113W / 10.2A / 0.632kg thrust
9x6   - 14.8V / 220W / 14.9A / 0.937kg thrust
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imsinking

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Re: Brushless motor running rough above half throttle
« Reply #2 on: May 01, 2016, 09:20:27 AM »

I'm new to Brushless myself ,but try running ONE motor on the ESC & not two, see if that makes any difference , a brushless ESC is totally different to a DC ESC actually alternates the current (+ to -) many times a second as well as controlling the voltage , can it be being confused by two motors ?. . .
I also dont know if you can run two ESC's thru one radio feed , would you need to be in tank ?
If we don't ask daft question's we wont find the right answers !  :embarrassed:
Bill
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TomHugill

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Re: Brushless motor running rough above half throttle
« Reply #3 on: May 01, 2016, 09:27:12 AM »

I have been told you need to run one esc per motor with brushless, I would try again with both exc soldered up and see what happens
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inertia

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Re: Brushless motor running rough above half throttle
« Reply #4 on: May 01, 2016, 09:50:16 AM »

You do need one ESC for each motor but you can get away with just one battery for the pair. It possibly won't run for very long.
You can run both ESCs from the same receiver output using a Y-lead BUT you need to disable the BEC from one of them by removing the red wire from the 3-pin plug (I wish I had a quid for every time I've written that...).
15000 RPM for a model boat prop strikes me as being very fast indeed.
DM
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TomHugill

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Re: Brushless motor running rough above half throttle
« Reply #5 on: May 01, 2016, 10:47:04 AM »

You do need one ESC for each motor but you can get away with just one battery for the pair. It possibly won't run for very long.
You can run both ESCs from the same receiver output using a Y-lead BUT you need to disable the BEC from one of them by removing the red wire from the 3-pin plug (I wish I had a quid for every time I've written that...).
15000 RPM for a model boat prop strikes me as being very fast indeed.
DM

Surface drives are closer to 25-30k I belive. My jet units are 15-20k
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inertia

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Re: Brushless motor running rough above half throttle
« Reply #6 on: May 01, 2016, 01:02:34 PM »

Surface drives are closer to 25-30k I belive. My jet units are 15-20k

Quite so, but from his earlier posts I understand that Ultrarep has a 36" Riva Aquarama. I run my 28mm 750kv motors on 3S but have changed to 2S for the 1000kv version - so that's somewhere between 7400-8300RPM. Both are turning PropShop 1315 3-blade scale props and give plenty of power and duration with no cooling except the air around them. The only thing which might contribute to this is that the boats are very lightly built.
DM
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red181

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Re: Brushless motor running rough above half throttle
« Reply #7 on: May 01, 2016, 06:29:03 PM »

DM is on the money, with brushless set ups, its one motor to one esc. I'm surprised you even got them to run at all, and as DM says, you can connect both esc's to one power source via "y" lead but with one signal (red) wire disconnected.

Personally, I disconnect both, and power the receiver with a separate battery, such as  4 x 1.5 aa's, or 5 x 1.2v rechargeable aa's. Then you just need to ensure the receiver powers up BEFORE the esc's.

You may have damaged the esc, hopefully not. I use NTM motors in a variety of models, mostly planes, they are very good for the money!

Sorry if stating the obvious here, but disregard the prop test data, that's for planes :-))
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Ultrarep

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Re: Brushless motor running rough above half throttle
« Reply #8 on: May 01, 2016, 09:12:28 PM »

Hi all


Just to clear up apparent missconceptions as I may not have been overly clear at two this morning.


I have two full systems for the twin set up in the Riva
I had only as of last night soldered all the connections to one ESC.


I tried each motor on that ESC (one at a time) to see if they both ran rough and they did.


I was running just the motors. Ot props yet as just checking it all works ok and found this rough running and hild back issue .


I only have the 4s packs so cant try it on 3S


I have run all four channels on th tx (one at a time) to check each through the esc and motor and all channels give the same rough running.


Could this be caused by the motor being un loaded?


Every possible setting on the esc has been tried to no avail.


I will get the second ESC setup this week to see if it may be the one ESC that I have tried.


Hope this answere some of the comments and clears the way for any other ideas.


Oh and thanks to all so far
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inertia

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Re: Brushless motor running rough above half throttle
« Reply #9 on: May 01, 2016, 11:10:19 PM »

There are a limited number of possibilities here:
1. The speed controller is set up incorrectly (number of motor turns and timing are particularly relevant)
2. The motors are faulty
3. The radio is faulty
4. The running gear is faulty.
5. The battery is faulty.

You say you have set up the ESC correctly. Despite this I would return it to the default settings and leave it there for the testing phase.
If both motors exhibit the same tendency then it's unlikely that you have been sold two faulty motors.
You have tried the ESC on all four channels and the problem persists. Before you can eliminate that entirely I would suggest trying another radio. There may be compatibility issues.
If the motors are connected to the prop shafts etc then disconnect them for testing.
Make sure the battery is fully charged. Try the tests with both batteries in turn.

I would try the other speed controller next, as you say. I reckon the problem is most likely to be in the ESC you've already used.

DM
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davidm1945

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Re: Brushless motor running rough above half throttle
« Reply #10 on: May 01, 2016, 11:19:35 PM »

Sorry - posted question then answered it myself - ignore.... :embarrassed:


Dave.
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derekwarner

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Re: Brushless motor running rough above half throttle
« Reply #11 on: May 02, 2016, 12:35:13 AM »

ultra................with my limited understanding of the BLACK arts, one of the scary issues is the cost of being able to electronically test & understand the root cause of performance scenarios

Your originally used the term 'run rough over 1/2 throttle' & 'not revving freely'

'run rough'..if the motor setup was running smoothly as opposed to roughly, you could easily determine at what RPM range this roughness was introduced....is it an electrical audible roughness, or a audible mechanical roughness or a  vibration roughness?....when the roughness occurs, does the motor RPM decrease?

'not revving freely'..I find also difficult to relate to an electronic sense for an electric motor

If the motor is left running in a smooth condition [at a lower voltage] for a given time period [say 5 minutes], have you measured the motor temperature?..... and then increase the voltage & introduce the roughness for the same given period and check the motor temperature again? 

One each of those $20.00 digital laser tachometers [2.5 to 99K RPM with an accuracy of +/- 0.05%] and a $20.00 digital laser pyrometer [-50 to +350 degree C] are pretty cheap diagnostic tools which may help you understand your issue

It would never be money wasted, as if you get sick of fast electrics, they are invaluable in model steam engine applications {-)...

As red181 notes, the motor data [current draw] is with the [aeroplane] propeller loadings, so can these motors with the 4S electrical supply and without the propeller blade over speed beyond the 'Kv: 1000rpm/v'?

Derek
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Ultrarep

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Re: Brushless motor running rough above half throttle
« Reply #12 on: May 02, 2016, 08:18:18 AM »

Update and thanks to you all


After reading all your ideas I spent some more time playing with it all last night.


I found that with some methodical testing ingot to one ofmthe available timing settings that minimised th rough running at only the very last milimetre of stick travel and then taking that channels end point adjustment down to 96% eliminated the issue completely atbthis timing seting.


I dont think that last 4% ofnthrottlemis going to be of great importance to tme so I will live with that


So I now have a smooth running motor system to fit to "Grace" yes it has a name!


Thanks to you all for the advice.
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steamboat66

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Re: Brushless motor running rough above half throttle
« Reply #13 on: August 07, 2016, 09:16:58 PM »

unloaded brushless motors can, in some setups, run rough at high RPM. it is not recommended to run them unloaded.
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