Electric Skateboard Brushless Motor not turning when applied weight

Other Hardware Motors, Mechanics, Power and CNC
1

I have an electric skateboard brushless motor connected to a 120A Flycolor ESC with Arduino UNO Servo library. The batteries are 2x 11.1V 3S 5000mAh Lipo in series.

Basically, the motor control turns perfectly well when the skateboard is flipped over, but will make a loud grinding sound and not move when the weight of the skateboard is on the wheels.

What could be the reason for this?

2

Can you provide good pictures of every component, the chain drive system (is it?), everything?

Also, provide the datasheet for all components, such as motor and ESC?

And a schematic (even hand drawn) of the electrical system.

Finally, just for good measure, please paste your Arduino code (even if working as intended) using code tags.

I can't think of what the issue might be apart from friction in the drive system under its own weight maybe (a guess), but providing the details I asked is your best bet to attract other forum members far better in the know than I.

3

Your batteries cannot supply enough current to run the motor with a load

4

I'm pretty sure your skateboard motor isn't a servo. A servo is an "angle motor" that rotates less than 360 degrees.

Is the battery voltage holding up when the motor is under load? Do you have a multimeter?

6

Also, how hot does this get under both conditions? Careful if you're not using a temp gauge, if you finger test it, be prepared for it to be hot - always be safe, right?

8

Sorry, thought this would be a simple power problem.

Wiring:

  • 2 batteries connected in series, then +/- end connections to the ESC thick red and black cables
  • 3-phase motor connection to the ESC
  • 3-pin 5V/GND/Signal connector to Arduino UNO's 5V, GND, and pin 9.

Arduino UNO Code:

#include <Servo.h>
#include <SPI.h>
Servo ESC;

void setup() {
  ESC.attach(9, 1000, 2000);
  ESC.write(180);
  delay(2000);
  ESC.write(-180);
  delay(1000);

}

void loop() {
  ESC.write(100);
  delay(1000);
  ESC.write(0);
  delay(1000);

}
9

Ok, so quick added details in your batteries:

50C @ 5000mAh 6S (higher voltage doesn't change C or capacity though) would be:
Available Amperage at 50C Rating: 250A
Charge/Discharge t (run-time):0.02 h
Charge/Discharge in minutes (run-time):1.20 min
source https://www.batteriesinaflash.com/c-rating-calculator

And for the motor, it says:

  • 【Powerful system】The Max Output Watt is 2450W, Max Current: 65 Amps,Max Volts: 12S .Recommend ESC is 3-12S 50A (eFSESC4.12 50A or FSESC 6.6 60A) 190KV

and the esc:
2-6S (you have 6S) 120A continuous current, 720A "Burst Current(10S)". It seems your ESC was designed for an RC boat and features two tubes along the length of it to allow water to pass through and cool it.

1st thought: (because of grinding noise you describe)

  • still something to do with drive system, although yours seems to be a belt driven system now that I've seen the motor, is everything moving properly with no batteries attached when it's on its wheels? Like moving things by hand?
    One of the reviews for your motor (unfortunately) has this to say:

Bearings are junk. Got it for small ebike. It went about 100 yards before bearings burned up.

2nd thought:

  • that ESC isn't going to cut it. Notwithstanding the grinding noise, but does that ESC go into shutdown mode if you ask more than it can give? I have similar ones for 1/10 scale RC monster trucks that do, such as the Velineon 3S ESC by Traxxas.
10

Have you read the reviews for that ESC?
Sounds like it's junk
I would buy one of the ESC recommended by the makers of the motor

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11

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