I have built a battery level indicator and have tested with a 12V battery Would it harm my arduino board if I connect a 48V battery? - Arduino Stack Exchange
Arduino 12v Power Supply With Cover Switch Dc Battery Box Aa * 8 12v Battery Holder - Parts & Accs - AliExpress
Trying to connect 12V DC irrigation pump using Relay and power supply - Motors, Mechanics, Power and CNC - Arduino Forum