My 2010 Equinox has got every feature that a modern automobile should have. However, one thing that I personally find missing is the real-time monitoring of voltage across the car’s battery terminals. This may not seem to be that important but one of the most common reasons for a car battery failure is the faulty charging system. If the charging system is not working properly, the battery will not get the proper charging voltage (about 13.8 V for 12V battery) across its terminals and it could go flat. This project is about making a simple electronic voltage monitor system for car’s battery and its charging system. It plugs into the car’s cigarette lighter receptacle and displays the instantaneous output voltage across the battery terminals on a 4-digit seven segment LED display. This helps you to get early warnings for possible battery and its charging system problems. Microchip’s PIC16F1827 is the main controller in this project, which uses the built-in Fixed Reference Voltage (FVR) module to achieve a very precise and accurate A/D conversion of the battery voltage.
Car's battery and charging system voltage monitoring device