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Old 04-06-2010, 11:31 AM   #1
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Default Bad Brushless motor ?

How do know or check to see if a brushless motor has or is going bad? Thanks
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Old 04-06-2010, 12:19 PM   #2
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I think the only way would be to hook it up to a brushless esc and see if it works. It's not like a brushed motor where you could just apply voltage to get it to spin.

Why do you think it is bad?
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Old 04-06-2010, 12:44 PM   #3
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You can check continuity across the motor leads, any probs with windings would show up there. If it won't run when iots hooked up, check batt voltage and then check voltage at esc motor leads - they should be real close. If the voltage is diff, may be teh esc, if voltage is almost the same, its prob motor.

If its a prob with the rotor, short of one coming apart and not wanting to turn, don't know any way to check that. If motor has seen enough high temps, it can demagnetize and just stops working.
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Old 04-06-2010, 01:46 PM   #4
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It got a high temp 1 time over 220 deg. Ever since then a 5 to 8 min. run it will just about burn you to touch it, esc and motor. Shuts down. I've played with different gear ratios, no change. I've tried 2 different esc's also, no change. The only thing that I haven't changed is the motor. I'll try that next. Thanks
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Old 04-08-2010, 06:49 AM   #5
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Default Another way to test your BL motor

I'm not sure how much you know about these little beasties....but they are built in theory similar to a motorcycle alternator....in fact.....nearly exactly. If you're running cars....you are probably using an in-runner type. Most of the aircraft guys use out-runners....where the moving piece of the motor is a bunch of strong magnets glued to the inside of a bell housing surrounding the field. The whole system is a lot like a three-phase alternator. Without pulses from the ESC in the correct sequence....the motor won't run. I haven't had a motor go defective yet....but I have had an ESC lose a phase. The motor just sits there & gets hot....grunts....but doesn't turn.
Now the test.... Remove your motor and chuck the shaft in a drill....or better....a drill press. Secure the non-moving part of the motor so that it won't turn. Spin it up to make sure all is secure....you certainly don't want to see your motor go flying across your shop. With the motor shaft spinning at as high a speed you can muster from your drill...get out your volt meter....set it to AC vots and measure the voltage between all leads. They should all be about the same. If not..... one of your windings has shorted or maybe open. If your motor gets warm during this test.....it's defective.
Flash
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Old 04-08-2010, 12:38 PM   #6
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Hey thanks for the quick test of the motor. I'll try it in a bit. Thanks
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