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
IoT Lithium Battery Monitoring system using ESP8266 & Arduino IoT Cloud
Battery Voltage Indicator using Arduino and LED Bar Graph
12V Electric Quantity 4 Power Indicator Battery Detection Module for Arduino TOP: Amazon.com: Industrial & Scientific
Displaying Battery Life on a Liquid Crystal Display (LCD) : 4 Steps (with Pictures) - Instructables
Monitoring a LiPo battery while powering the Arduino UNO with it - Project Guidance - Arduino Forum
Arduino battery control charge and discharge Battery Level Indicator - YouTube