In this project learn how to make an LED battery level indicator using an LM3914 and some LEDs. The device will also feature a buzzer to alert you when your battery's voltage is too low and needs charging.

Each LED represents 10% and when the battery voltage falls below 40% the buzzer will sound alerting you to charge the battery.

To set the 100% voltage adjust the 10k potentiometer connected to pin 5 so that the 100% LED turns on at the voltage at which the battery will be 100% charged. I would suggest connecting a adjustable power supply to the circuit to set these values. For example you want to use the circuit with a 12V battery set your power supply to 12V

Once the 100% voltage has been set the power supply to 10% of the voltage you set in the first step and adjust the 200k potentiometer until the 10% LED lights up. Once this is done you have successfully set up the device and can now connect your battery.

You can adjust the brightness of the LEDs by turning the 10k potentiometer connected to pin 6 and 7 until the LEDs are at a suitable brightness.

Schematic

If you would like you could build the circuit on a PCB. I have designed a PCB for you so that the circuit is easy to build and easy to connect to the battery using the screw terminals. I have attached the Gerber files for you to use.

PCB

Website

Check out more of my other projects on my website.