Problem powering 2wd obstacle avoidance robot

Hi Guys,

I am very new to Arduino. Need you guys help on this one. I have started to build my first Arduino project which is a 2wd obstacle avoidance robot with instructions from the net. Basically the robot runs on 2x 1:48 DC gearmotors, a 9G servo motor which is used to rotate the ultrasonic sensor.

I am using the L293D motor shield. When I load the code into the Arduino it all works fine. But when I remove the usb, the wheels start to turn incorrectly. I am using a 9v battery to power both the arduino and motor shield.

From my findings, it is advised not to use the 9V battery and keep the power supply for the motor shield separate from the Arduino.

My question is if the power supply is to be separate, is there any jumpers that I need to connect or remove? Or cut any legs from the motor shield? And how much power supply (batteries) should I use to power up the motor shield?

PS. Any way to prevent the robot to start powering up via the usb when loading the code?

rajendran:
Hi Guys,

I am very new to Arduino. Need you guys help on this one. I have started to build my first Arduino project which is a 2wd obstacle avoidance robot with instructions from the net. Basically the robot runs on 2x 1:48 DC gearmotors, a 9G servo motor which is used to rotate the ultrasonic sensor.

I am using the L293D motor shield. When I load the code into the Arduino it all works fine. But when I remove the usb, the wheels start to turn incorrectly. I am using a 9v battery to power both the arduino and motor shield.

From my findings, it is advised not to use the 9V battery and keep the power supply for the motor shield separate from the Arduino.

My question is if the power supply is to be separate, is there any jumpers that I need to connect or remove? Or cut any legs from the motor shield?

That is going to be hard since we don't know what shield you are using. A link to it would help.

And how much power supply (batteries) should I use to power up the motor shield?

Again, have no idea what the recommended supply is. But as long as you are not using a PP3 9V battery, you're doing good. I am going to guess that at least AA batteries would be needed for the ~3A that will be needed.

PS. Any way to prevent the robot to start powering up via the usb when loading the code?

You can disconnected everything from the arduino while uploading.

Hi,

Thanks for the reply. I am using a Adafruit L293D motor shield.
Overview | Adafruit Motor Shield | Adafruit Learning System.

How many volts or AA batteries needed?

Regards

It says it on the first page you linked to. AA batteries are ~1.5V each.