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Author Topic: Brushless Problem - Help please.  (Read 2175 times)

Bugsy

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Brushless Problem - Help please.
« on: January 17, 2011, 10:18:27 AM »

Had the first trials with my new boat yesterday and it went really well, at first.

Its a scratch-built semi-scale US Coastguard Patrol, one metre in length and running two outrunner motors

http://www.giantcod.co.uk/keda-thumrun-2837-outrunner-brushless-motor-p-403681.html

On my second run the left-hand motor  started to make a strange noise and closer inspection revealed that when power was supplied it was struggling to run. All screws tight and no tightness on the shaft but just a horrible noise, a bit of smoke (eventually) and generally bu**ered.

Any ideas welcome, have I just got a bad one, or should I try a replacement or bite the bullet and fit a couple of brushed Graupners.

Thanks.
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nick_75au

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Re: Brushless Problem - Help please.
« Reply #1 on: January 17, 2011, 10:46:19 AM »

A screeching noise indicates that either the timing set in the ESC is too low or there is excessive load on the motor, do you have sufficient play in the shaft? is the shaft in anyway tight. Are there loose magnets in the bell?

It sounds like the motor may be toast, to check measure the resistance between the 3 leads, a toast motor will probably have a difference between 2 of the 3 wires.

What size props are you using?

Nick
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Martin [Admin]

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Re: Brushless Problem - Help please.
« Reply #2 on: January 17, 2011, 10:56:46 AM »

Also, was it the motor that 'released the magic black smoke' or the speed controller?
If it was the motor, have you tried the speed controller on the other motor, just to check it?
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Bugsy

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Re: Brushless Problem - Help please.
« Reply #3 on: January 17, 2011, 11:07:33 AM »

Thanks for a quick response guys.

I,m running both motors through one 60amp speed controller and the right engine runs fine, the left one doesn't.

The shaft is free-turning and both shafts have the same amount of play.

The slight wisp of smoke came from the left motor only when testing it on-shore.

I'm running 40mm left & right brass props.

The motor is 'toast' as there is burning on one of the windings. The magnets are all in place but there is some variation in their spacing.

.
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Martin [Admin]

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Re: Brushless Problem - Help please.
« Reply #4 on: January 17, 2011, 11:21:43 AM »

As far as i know, you should only run one brushless motor through each speed control.....
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Bugsy

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Re: Brushless Problem - Help please.
« Reply #5 on: January 17, 2011, 11:46:57 AM »

Thanks Martin, as this is my first venture into brushless I had no idea on that. A quick 'google' has revealed that its pretty much a no-no.

The decision now is whether to buy another motor and an additional esc, or simply two brushed motors and a new esc. Either way, its going to cost. :-)
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nick_75au

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Re: Brushless Problem - Help please.
« Reply #6 on: January 17, 2011, 11:52:04 AM »

+1 for what Martin has said,
You can't run 2 brush-less motors off one ESC, they measure current from the un-powered winding to drive the next winding (part of the timing), the motors are never perfectly in sync so that is why the motor toasted.

Those motors should have no problem with a 40 mm prop up to around 18 volts, so the load is OK.

NicK
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Bugsy

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Re: Brushless Problem - Help please.
« Reply #7 on: January 17, 2011, 12:38:49 PM »

Thanks Nick, Life is a constant learning curve I guess.  ;)

I've just put the faulty motor back together and tried it connected to the esc with the good motor disconnected. Revs like hell then stutters and starts to smoke, its destined only for that place in the sky where all dead motors go.

Connecting the good motor to the esc and it runs perfectly, so I'm guessing that the esc itself, is OK.

I'm seriously thinking about getting two brushed motors now.
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Bugsy

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Re: Brushless Problem - Help please.
« Reply #8 on: January 20, 2011, 06:34:35 PM »

Well, I've decided to stay with brushless on this project so i've ordered two of these

http://www.giantcod.co.uk/xyh3542-1100kv-brushless-outrunner-p-403782.html

a bit more powerful than the first ones I bought and a second Hobbywing 60a speed controller.

Time will tell.  :-)
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