Hello everyone. I purchased a robot chassis recently and was checking if it was working. I connected 4 motors of the chassis to motor shield connected to arduino and connected a 9v battery to the motor shield. I tried a simple program to run the chassis forward for 10 seconds and backward for 10 seconds. When i connect arduino to pc via usb the chassis is running well but while using 9v battery to the arduino the chassis is not moving and only a noise is produced. I even tried connecting two 9v batteries in series but it didnt work. The chassis is running only when connected to pc via usb.
Can anybody plz tell what went wrong? :(