Go Down

Topic: Motor Shield does not deliver enough power..please help (Read 1 time) previous topic - next topic

mujahed1987

Feb 20, 2013, 12:06 pm Last Edit: Feb 20, 2013, 12:21 pm by mujahed1987 Reason: 1
Hello everybody
I am using motor shield in hacking an R/C car. my power source is Ni-MH 1800 mAh 7.2V battery which comes with the car. By default this battery is enough to drive the car but when using the motor shield the DC motor is not rotating at all(only low whistling sound) using multimeter the current delivered to the motor is about 1A but the motor need at lest 1.5A please tell me what is the best solution. should I use another battery with larger mAh or can I use a general amplifier to amplify the current ??

Erdin

Which Arduino board are you using ?
Which motor shield ? and which library for the motor shield ?

JimboZA

If the shield uses a chip like the 298 (and we don't know because you didn't tell us what shield you have... hint hint  8) ), it will lose you 2-3 volts which will take you down to the 4-5 volt realm at the motor.
Johannesburg hams call me: ZS6JMB on Highveld rep 145.7875 (-600 & 88.5 tone)
Dr Perry Cox: "Help me to help you, help me to help you...."
Your answer may already be here: https://forum.arduino.cc/index.php?topic=384198.0

mujahed1987

Hi
I am using arduino motor shield this one. arduino.cc/en/Main/ArduinoMotorShieldR3
With arduino uno there is no any library.
The output voltage at the motor channel is same as the battery voltage which is 7.2V.. The problem is with the output current which goes to the motor and i want to know how to increase the current. Is it by increasing the power source current only or I can use power amplifier?

JimboZA

Well that does use the 298, and according to the 298 datasheet it drops between 1.8 and 3.2 volts
Johannesburg hams call me: ZS6JMB on Highveld rep 145.7875 (-600 & 88.5 tone)
Dr Perry Cox: "Help me to help you, help me to help you...."
Your answer may already be here: https://forum.arduino.cc/index.php?topic=384198.0

Erdin

I understand you want more current, but something else is going on.

The motorshield is able to deliver 2A. So the current should be no problem.
If you measure an output voltage of 7.2V while the motor is on, that seems not right.
The output of the L298 is about 1 or 1.5V less then the maximum. So the output of the H-bridge is about 2 to 3 Volts lower than 7.2V. That might be too low to get the motors running.

Perhaps you could write a very small sketch, just to turn the motor on. If you upload the sketch we can take a look at it.
You could use a motor driver with mosfets. They don't have that voltage drop of 2 to 3 Volts.

The sound could be a low voltage, but it could also be the sound of the Arduino PWM. That is about 450Hz. Perhaps you use a PWM output, which is too low for the motor.

Go Up