Output voltage on motor shield v3

Using Arduino Motors, Mechanics, Power and CNC
1

Hello

I need to use motor shield R3 with a Nikko car.
I use the original battery 7.2V

When my motors are not plugged to the output of the shield, I have a voltage about 7V.
When my motors are plugged to the output of the shield, I have a voltage less than 1V, not suffisant to turn the wheels.

I tested with an other motor shield (v1), I have the same problem.

Anyone got an idea ? Thanks

2

Please supply a drawing of how you have connected it and the code you are using to drive it.

The fact that you have tried other shields tend to suggest a connection or code fault. You have supplied neither.

Weedpharma

3

The arduino is powered with a small 9V battery.

The motor shield is powered with the big 7.2V original battery of the Nikko car, on the Vin and Gnd screws.

I have cut the "vin connect" jumper.

With the motor shield R3 the code is :

// Le moteur fait avancer puis reculer les roues
void setup() {
//Setup Moteur
pinMode(13, OUTPUT); //Sortie utilisée pour initialiser le moteur
pinMode(8, OUTPUT); //Sortie utilisée pour le frein du moteur
pinMode(11, OUTPUT); //Sortie utilisée pour la vitesse du moteur
}

void loop(){

//avance à pleine vitesse
digitalWrite(13, HIGH); //Direction "Avancer" pour le moteur
digitalWrite(8, LOW); //Désactive le frein du moteur
analogWrite(11, 255); //Fait tourner le moteur à pleine vitesse

delay(3000);

digitalWrite(8, HIGH); //Active le frein pour le moteur

delay(1000);

//recule à une vitesse moyenne
digitalWrite(13, LOW); //Direction "Reculer" pour le moteur
digitalWrite(8, LOW); //Désactive le frein du moteur
analogWrite(11, 160); //Fait tourner le moteur à moyenne vitesse

delay(3000);

digitalWrite(8, HIGH); //Active le frein pour le moteur

delay(1000);

}

The fact is when i don't plugg the motors i can mesure the good voltage on the screws (output of the shield), but if i plugg the motors into this screws, the voltage is really down.
I can't understand this.

Thanks for your help

4

Hi,
Does this voltage drop happen when you are running your code! or just when you test it static??
You say you have the 7.2v input on the Vin and ground on the shield, but then say you have CUT the Vin on the shield.

How is the 7.2v battery connected?? are shield and Arduino GNDs commoned together.?? What motors are you using, are they drawing a lot of current, this would drop the voltage too.

What about letting us see a schematic or drawinf of same, etc, motor details, etc.

Hope it helps, regards see my bots here: www.melsaunders.co.uk under Electronics.

Mel.