Schematic Diagram

3 LED battery monitor circuit

This is the schema diagram of a 3 LED bar graph type battery monitor schema that is ideal for monitoring the voltage level of an automobile battery





When battery voltage is 11.5V or less transistor Q1 will be On and the LED D1 will be glowing.When battery voltage is between 11.5 and 13.5V, the transistor Q2 will be On and the LED D2 will be glowing.When battery voltage is above 13.5V the transistor Q3 will be On and the LED D3 will be glowing.




Notes.

* Assemble the schema on a general purpose PCB.
* The battery to be monitored can be connected between the terminals namely A and B.
* It is always better to use LEDs of different colour.