Arduino+potentiometer+ brushless motor= burned motor

hello guys,

I was testing my motor with the arduino signal using a potentiometer. The circuit was very simple, I used Servo>knob code and used the output in the 9 pin to send the signal to the ESC's and then make the motor work. Well, here it is the problem, on my first try, the motor worked but his speed had some variation, until there no serious problem. On my second try, the motor made a beep (one single) and run start until an high speed and suddenly he burned,the result was a lot of white smoke and very heat on the motor.
What could be the cause of this?

One photo the motor is working and the other is burned.

It sounds like you fried the motor coils from over current.

The cause of this can vary greatly.

Did you calibrate/program the ESC to match your output? Because ESC are designed to work with R/C remotes and all remotes have different ranges you must calibrate it for your current output (arduino).

I assume you connected the ESC ground to the arduino ground, although voltage doesn't directly play a part in speed control, having a floating voltage on the signal would in theory cause some data corruption.

The voltage of the ESC must be equal or lower then the voltage rating of the motor. Based on what you said I wouldn't be surprised if you where over volting the motor. Never mind the inability to control the speed, if it was the correct voltage there shouldn't be any damage to the motor even if its being driven hard.

Maybe it was just the motors time to go. Motors that have had long or hard lives will wear out the coil windings, that one last hard drive just pushed it over the edge. When one coil fails it usually takes others with it.

Run a motor without a prop and it has no forced air cooling, so you have to be very
careful not to overload them. Having said that they should not pull that much
current with no load.

If one of the windings comes disconnected/intermittent the current imbalance will
lead to much higher currents flowing and rapid failure.

Monitor the current into the ESC if you want to avoid future disasters.

Your next project may be rewinding a motor!

Coil windings cannot "wear out" if they are fixed in place with electrical varnish,
as they cannot vibrate and rub each other. Typically windings in larger motors
are just dipped in hot varnish as part of manufacturing to ensure a long life

By wear out I clearly mean heat fatigue on the copper and its insulation. The insulation is thermally resistant not thermal proof, every time it gets exposed to heat it gets a little bit of cooking time. In combination with the expansion and retraction caused by the heat, eventually the insulation will just fail. Given the nature of hobby motors and lower quality then found in other professional industries, I would think a few years puts it into the grandpa age range.

Not excluding the wear of the bearings in the motor, if they start to jam, the motor will go into stall and that can easily cause the coils to fail.