Lead Acid Battery Voltage Monitor using ATMEGA328

  • Rajkumar Sharma
  • 443
  • moderate
  • Tested

Monitoring the voltage level of a 12V Lead Acid Battery (SLA) is easy and simple with this project. The board is made using an ATMEGA328 micro-controller and 12 x 5mm LEDs. The ATMEGA328 microcontroller senses the analog voltage on A3 Analog pin and drives 12 LEDs connected to digital I/O pins of the chip. Input voltage from the battery is dropped using divider resistors. Different colors of LEDs used for easy visualization of battery voltage level. The operating supply of the circuit is 7-15V DC. The battery voltage measuring range is 9.75V to 14.5V. LED Vs voltage level can be changed by modifying the Arduino code.

Example Code is available, check on downloads below. This Code is written with the help of Arduino IDE, so new ATMEGA328 chip requires bootloader burning and code uploading, more info on programming the chip is available here:



  • Supply 7-15V (Advisable to use 9V PP3 Battery) @ 80mA
  • Measuring Range 9.75V to 14.5V
  • Blue LED = Fully Discharged or Faulty Battery
  • Green LEDs = Healthy Battery
  • Yellow/Red= Over Charged Battery


Parts List

Voltage Table


Gerber View




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