I am running two 12v 12amp motors.
I recently tried to brake my motors with your library with the brake statement (md.setM1Brake(400) it works but the braking seems a bit weak even at 400 my robot is not stopping fast enough.
Is there another way to brake it more efficiently?
I have been putting the motor in reverse(-50pwm) to stop it, but Im scared I might damage the motors or the driver?
400 corresponds to 100% braking for that function. So, if that does not stop fast enough, you might try commanding the motor to run in reverse like you suggest, which is the only other straightforward method we know of to brake any faster. However, you are right, it will be harder on the driver and motor. How acceptable this increased load is depends on how much current your motor is drawing. What kind of mechanical load is on your motors? What is their stall current?