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Why would an esc burn up motors?

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Why would an esc burn up motors?

Old 08-03-2020, 09:52 AM
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Default Why would an esc burn up motors?

Hi everyone,

My son was playing with a sensored set up 10.5 t, 120 a, in a 2wd buggy. His friend had immobilized the buggy with his foot on the feels, and I hadn't informed my son about not applying throttle in such a situation so he had the throttle on for I think a relatively short period.

The slipper was set up correctly, as I have tested it at home and it would wheelie and slip when I held the rear wheels still. It still burnt out somehow, not sure why.

I thought it was the motor, as when I was checking it the motor would smoke a bit. So I took it home and switched the motor - immediately the new motor would start to get very warm without applying any throttle.

So I then thought the esc was the only thing gone, tried the questionable sensored motor in a different esc, runs, but much slowly, perhaps 50% but in a sensorless esc.

Two questions:

1) if the questionable motor still runs, but at 50%, is it because it is with a sensorless esc, or is the motor likely toast?
2) what is the mechanisms where just hooking up a new motor to the questionable esc, that it would start to get so so warm within in a maybe 10 seconds?

Thanks

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Old 08-03-2020, 10:10 AM
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Timing is an issue with brushless. With sensored you can set a mechanical timing by the position of the sensor plate and an electronic timing in the ESC. Together they make the total timing.

Taking out the sensor, let it run as sensorless is taking away that part of the timing. And using another ESC you should look at the configured timing.
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Old 08-03-2020, 12:23 PM
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Thanks, that makes sense. Once I get a new sensored esc I will try the motor again.

How about the question number two? I am certain the esc is toast since it heats up the motor so quickly, but I have no idea of the mrchanism.
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Old 08-03-2020, 12:37 PM
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My guess is a transistor breakdown or circuit short in the esc, feeding high current to one wind (or more?). The current can quickly go higher, full time on not intermittent like normal, lots of heat can be generated pretty fast.
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Old 08-03-2020, 12:46 PM
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If you had too much timing the current will go up and so the heat in the ESC and motor. (and battery

Another thing that can distroy the ESC when you had no capacitor on the battery power lines.
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Old 08-03-2020, 03:10 PM
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Originally Posted by Dave H View Post
My guess is a transistor breakdown or circuit short in the esc, feeding high current to one wind (or more?). The current can quickly go higher, full time on not intermittent like normal, lots of heat can be generated pretty fast.
Makes a lot of sense. Thanks
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Old 08-03-2020, 11:18 PM
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It sounds like the ESC is burned up and has half a phase with shorted MOSFETs. If you have a multi-meter with a continuity check you can touch one probe to the + wire and then check all 3 motor outputs with the second probe and then move the first probe to the - wire and check all 3 motor outputs again. None of the motor outputs should show as connected to either of the input wires.

The motor only spinning 50% may be because the radio has it's throttle channel backwards. I don't know how it is on other brands, but on Castle ESCs the default settings have 100% forward power and 50% reverse power. Some radios(normally Futaba) have their throttle channel reversed by default. This causes the ESC to apply forward power when you want reverse and reverse power when you want forward. If there are LEDs to indicate throttle position on the ESC, check to make sure it is correct. On Castle ESCs there is a red led for reverse/brake, a yellow LED for neutral, and green LED for forward.

Another reason it is only getting 50% throttle could be radio calibration. The ESC may be set to take a wider range of signals than your radio is putting out which is artificially limiting the top speed of the motor.
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Old 08-04-2020, 07:18 AM
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Originally Posted by [email protected] View Post
It sounds like the ESC is burned up and has half a phase with shorted MOSFETs. If you have a multi-meter with a continuity check you can touch one probe to the + wire and then check all 3 motor outputs with the second probe and then move the first probe to the - wire and check all 3 motor outputs again. None of the motor outputs should show as connected to either of the input wires.

The motor only spinning 50% may be because the radio has it's throttle channel backwards. I don't know how it is on other brands, but on Castle ESCs the default settings have 100% forward power and 50% reverse power. Some radios(normally Futaba) have their throttle channel reversed by default. This causes the ESC to apply forward power when you want reverse and reverse power when you want forward. If there are LEDs to indicate throttle position on the ESC, check to make sure it is correct. On Castle ESCs there is a red led for reverse/brake, a yellow LED for neutral, and green LED for forward.

Another reason it is only getting 50% throttle could be radio calibration. The ESC may be set to take a wider range of signals than your radio is putting out which is artificially limiting the top speed of the motor.
Thanks - out of curiosity I will check the continuity on the motor leads. I presume of course the esc does not have to be plugged into a power source for this?

As for the 50% - I did calibrate the esc again, and double checked the fwd / rev settings. The known good ESC I used with the questionable motor is sensorless, at the sensored questionable motor had timing set to mid range - as someone else mentioned that might account for the difference in speed? BUT - a replacement known good motor same size, sensorless, same KV, was much faster. Still a bit confused but assuming the questionable motor is burnt up I guess.
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Old 08-05-2020, 11:44 AM
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The worst thing a brushless ESC can do is send DC directly into a three phase motor and then it will burn out.



If the esc inadvertently glitched and went brushed on a brushless motor this is a bad thing.

A motor winding phase doesn’t partially work, it is either working or not and if that phase is out the motor will not spin. So the ESC will derate the highest phase if the motor still spin in either clockwise or counter clockwise.

Brand of esc?

Reverse is typically 50% of throttle max forward.

Does your ESC have a factory reset?

Does this questionable ESC work with other motors?

Testing continuity only tests the wire not the insulation, need a megger for that and it has to be fully removed from the circuit.
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Old 08-05-2020, 12:06 PM
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Also make sure there are no solder bridges or wires touching each other at the Motor ABC connections or the ABC + - the ESC, this can also result in the the motor getting really hot or burning up.

Great suggestion above too to check that no settings have been changed accidentally (eg. brushed mode but with a brushless motor).

Another thing that will quickly heat and smoke a motor is if the timing on the can is set to negative, make sure the timing adjustment on the motor hasn't moved or accidentally been set to zero.

Has the ESC ever been hooked up with reverse connection to the battery? Even if only for a moment, this can destroy the ESC and let out the smoke from ESC & motors. An ESC can keep ruining motors once it has been connected this way.
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Old 08-05-2020, 05:10 PM
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Originally Posted by Juglenaut View Post
The worst thing a brushless ESC can do is send DC directly into a three phase motor and then it will burn out.



If the esc inadvertently glitched and went brushed on a brushless motor this is a bad thing.

A motor winding phase doesn’t partially work, it is either working or not and if that phase is out the motor will not spin. So the ESC will derate the highest phase if the motor still spin in either clockwise or counter clockwise.

Brand of esc?

Reverse is typically 50% of throttle max forward.

Does your ESC have a factory reset?

Does this questionable ESC work with other motors?

Testing continuity only tests the wire not the insulation, need a megger for that and it has to be fully removed from the circuit.
I checked the manual. It is a hobbystar 120amp turbo model, and there is no option for brushed mode, so that's not it. I recall that immediately on powering up the esc there is a quick sound like a surge, or cogging even without any throttle, then the motor starts heating.

I will try a factory reset as I just got the pc link for it.
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Old 08-05-2020, 05:11 PM
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Originally Posted by mushroomed View Post
Also make sure there are no solder bridges or wires touching each other at the Motor ABC connections or the ABC + - the ESC, this can also result in the the motor getting really hot or burning up.

Great suggestion above too to check that no settings have been changed accidentally (eg. brushed mode but with a brushless motor).

Another thing that will quickly heat and smoke a motor is if the timing on the can is set to negative, make sure the timing adjustment on the motor hasn't moved or accidentally been set to zero.

Has the ESC ever been hooked up with reverse connection to the battery? Even if only for a moment, this can destroy the ESC and let out the smoke from ESC & motors. An ESC can keep ruining motors once it has been connected this way.
Timing wasn't changes, and battery never hooked up backwards. Solder connections good.
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Old 08-06-2020, 09:35 PM
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if the rotor was locked and load applied it could overheat in seconds. wrap a loose wire around all 3 phases and ground. rotate the motor and see if it the resistance feels even for a complete rotation. you should also feel 6 heavy lumps if its a 2 pole motor that should resist about the same amount for each lump. if you rotor wasnt locked and a winding wasnt damaged then you could have demagnetized the rotor a little or allot from chronic heat rather than acute heat.
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Old 08-10-2020, 07:20 AM
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Originally Posted by [email protected] View Post
It sounds like the ESC is burned up and has half a phase with shorted MOSFETs. If you have a multi-meter with a continuity check you can touch one probe to the + wire and then check all 3 motor outputs with the second probe and then move the first probe to the - wire and check all 3 motor outputs again. None of the motor outputs should show as connected to either of the input wires.
This was it! One of the motor leads had continuity with the negative lead. I guess this means the esc is garbage?
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Old 08-10-2020, 07:38 AM
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Originally Posted by Bry195 View Post
if the rotor was locked and load applied it could overheat in seconds. wrap a loose wire around all 3 phases and ground. rotate the motor and see if it the resistance feels even for a complete rotation. you should also feel 6 heavy lumps if its a 2 pole motor that should resist about the same amount for each lump. if you rotor wasnt locked and a winding wasnt damaged then you could have demagnetized the rotor a little or allot from chronic heat rather than acute heat.
Turning the shaft, I can feel 6 solid, equal lumps. In fact, it feels stronger than the replacement motor, same kv, which is faster though. If the resistance is strong and equal - should the motor still be fine?
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