Yet another voltage monitor for car’s battery
A couple of years ago I built a digital voltage monitor system for my 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. I used Microchip’s PIC16F1827 microcontroller and it’s built-in Fixed Reference Voltage (FVR) module to achieve better A/D conversion accuracy while measuring the battery voltage. Here’s an instructable on building a similar device but using ATtiny13 microcontroller. Instead of displaying real battery voltage, however, this project uses three LEDs as visual indication of battery condition.
Car’s battery voltage monitor