Battery Display Red and Green Battery Style Digital Tube LED Battery Level Display Module for Arduino|module for arduino|module ledmodule battery - AliExpress
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
A Simple Arduino Battery Tester - Pi My Life Up
Displaying Battery Life on a Liquid Crystal Display (LCD) : 4 Steps (with Pictures) - Instructables