18 volts are near the maximum limits and nowhere near the recommended voltage (7-12V). For further info, visit the hardware pages: http://arduino.cc/en/Main/Hardware
There you find the input voltages for every kind of Arduino
18 volts are near the maximum limits and nowhere near the recommended voltage (7-12V). For further info, visit the hardware pages: http://arduino.cc/en/Main/Hardware
There you find the input voltages for every kind of Arduino