Chip on motor shield get really hot in seconds

Other Hardware Motors, Mechanics, Power and CNC
1

I build an obstacle avoiding robot using tank treads and a tamiya twin motor gear box. The chip gets super hot right away this is my first project. if any one can help that would be great i am using a 2s lipo for power

#include <AFMotor.h> //import your motor shield library
#define trigPin 12 // define the pins of your sensor
#define echoPin 13
AF_DCMotor motor1(1,MOTOR12_8KHZ); // set up motors.
AF_DCMotor motor2(2, MOTOR12_8KHZ);

void setup() {
Serial.begin(9600); // begin serial communitication
Serial.println("Motor test!");
pinMode(trigPin, OUTPUT);// set the trig pin to output (Send sound waves)
pinMode(echoPin, INPUT);// set the echo pin to input (recieve sound waves)
motor1.setSpeed(105); //set the speed of the motors, between 0-255
motor2.setSpeed (105);
}

void loop() {

long duration, distance; // start the scan
digitalWrite(trigPin, LOW);
delayMicroseconds(2); // delays are required for a succesful sensor operation.
digitalWrite(trigPin, HIGH);

delayMicroseconds(10); //this delay is required as well!
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
distance = (duration/2) / 29.1;// convert the distance to centimeters.
if (distance < 25)/*if there's an obstacle 25 centimers, ahead, do the following: */ {
Serial.println ("Close Obstacle detected!" );
Serial.println ("Obstacle Details:");
Serial.print ("Distance From Robot is " );
Serial.print ( distance);
Serial.print ( " CM!");// print out the distance in centimeters.

Serial.println (" The obstacle is declared a threat due to close distance. ");
Serial.println (" Turning !");
motor1.run(FORWARD); // Turn as long as there's an obstacle ahead.
motor2.run (BACKWARD);

}
else {
Serial.println ("No obstacle detected. going forward");
delay (15);
motor1.run(FORWARD); //if there's no obstacle ahead, Go Forward!
motor2.run(FORWARD);
}

}

2

The motor shield probably cannot handle the current required by the motors.

If the shield has one of the ancient L293 or L298 chips, use a modern motor driver like these.

3

if i lower the gear ratio would that have the same effect? also did you see the part in the code about one motor being 64khz and the other was 8khz, what was that all about?

4

I am not sure how to do that PWM thick. I am not that in depth with my programming skills. But thank you for your time and consideration

5

is the part about the khz on the 2 motors correct?
thanks for your time and consideration

6

What is the stall current of the motor? What motor? Some details please.

7

when i set the motor speed below 90 or so it hums or buzzes but does not move. The motors came with the Tamiya twin motor gear box.
the operating range is 1.5 to 3V
current .66 with a load
2.20 is the stall current
1.5v in the nominal value.
Thank you for your help. I appreciate it.
Joe

8

What kind of motor driver circuit are you using?

9

I am using the Adafruit motor shield copy by DK
thanks

10

Do I have this straight:

You are using a 1.5V motor with a 7.4V LiPo pack and are surprized that things get hot?

11

Easy now. He/she is a beginner. We all have to start somewhere. At least the OP is smart enough to know to ask for help.

12

I'm just saying what appears to be the case, clearly, in case I've got the wrong end of the stick. I am
happy to be contradicted :slight_smile:

13

Thank you for all your advise. I did not realize the motor shield did not change the voltage to the motor. So I will try again with less power. Can I use the 7.2V lipo to power the Arduino itself? or am i asking for trouble?
Thanks
Joe

14

omcjoe:
Can I use the 7.2V lipo to power the Arduino itself? or am i asking for trouble?
Thanks
Joe

The specs reckons 7 to 12 V. But check this.... Arduino Playground - HomePage