I connected 2 12v drill motors to my arduino uno with motor shield. I hooked up an external power supply of 12 volts but the motors won't move. I tested the code and controller with smaller motors after I tried the big motors and it worked perfectly. I don't know what's wrong.
Maybe the huge current the motors draw burned out your motor shield.
I tested the code and controller with smaller motors after I tried the big motors and it worked perfectly. I don't know what's wrong.
Most likely the motor controller can't pass enough current to operate the larger motors. You probably need a controller that can handle more current.
Drill motors are way way beyond the ability of a lowly L298 or L293 motor shield, they are
seriously high current motors (30A or something of that order).
Try with a high current shield, like bts7960 or higher ones, they sell on ebay capacity like 50-100 amps
Drill motors are not designed to run continuously, note, they may overheat if expected
to do continuous duty.
What are you trying to do?