Hello,
I am having an issue powering my arduino uno with my motor shield. I have it plugged in just as it is to be, but the arduino will not work unless connected to a usb or barrel connector. Is there any way to power the arduino using the motor shield? The motor shield is connected to 4 AA batteries to supply voltage.
any shield plugged into arduino gets its power from the arduino 5 volt which is needed to control the low voltage logic and decision making aspect i.e the brains of it all. In the case of a motor or relay shield a separate power is usually connected to drive higher voltage/current devices like motors but is fed in a different path isolated from the arduino which has limited output current. If you simply tried to feed power back into the arduino via the 5 volt output header pins you would burn out its voltage regulator. The Arduino USB pin is used if your connecting to a computer or a 5 volt dc charger only not 9 or 12 volts. For voltages higher than 5 you must use the barrel jack which is fed through a 5 v regulator to supply the Arduino. Best solution use a 9v battery into barrel and separate 6,12,24 volts on the motor side some applications will require all supply grounds to be connected together others like a solid state relay driving a 240 volt ac device the grounds would not be connected. Any other magicians ways can result in a damaged Arduino board. So my answer No!