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 Use | Adafruit LC709203F LiPoly / LiIon Fuel Gauge and Battery Monitor | Adafruit Learning System
Open-samrt Battery Style Digital Tube Led Battery Level Display Module 4-color 10-segment Led Bar For Arduino - Industrial Computer & Accessories - AliExpress
Monitoring voltage of individual batteries connected in series using arduino uno
Battery level indicator - Project Guidance - Arduino Forum