12V Battery Low Voltage Alarm Circuit

Battery is very important in many electronic systems.

However battery voltage drops with time, if voltage becomes too low then battery can get damaged.

So low voltage indication is needed.

Therefore, this 12V Battery Low Voltage Alarm Circuit helps to protect battery.

It gives visual and sound alert and is simple and is with low cost.

Also it uses easily available components.

In this circuit the LM339 comparator IC is used which compares battery voltage with reference voltage.

When battery voltage goes low the LED and buzzer turn ON.

Circuit Working:

Parts List:

This circuit works on 12V DC battery and LM339 is quad comparator IC with only one comparator is used here.

First, battery is connected to input clips.

Then battery voltage is divided by resistor network and this divided voltage is given to comparator input.

Meanwhile Zener diode ZD1 provides fixed 6V reference and this reference is applied to another comparator input.

VR1 helps to fine tune reference level.

Now comparator compares both voltages and when battery voltage is higher than set level then output remains OFF.

So LED and buzzer stay OFF.

However, when battery voltage falls below preset value then comparator changes output state.

Then LED glows immediately and at the same time buzzer starts sounding.

Thus user gets clear warning and so battery can be recharged in time.

How to Build:

To build a 12V Battery Low Voltage Alarm Circuit follow the below connection steps:

• First start gathering all the parts as shown in circuit diagram.
• Pin 2 of IC is the output pin and is connected to Buzzer ,R2 and LED.
• Pin 3 of IC is the Vcc pin and is connected to positive supply.
• Pin 4 of IC is the -input1 pin and is connected to positive supply through resistor R1.
• Pin 5 of IC is the +input1 pin and is connected to center pin of VR1 pot.
• Pin 12 of IC is the GND pin and is connected to negative supply of battery.
• Zener diode cathode is connected from pin 4 of IC and anode is connected to negative of battery.
• Two probes are connected to 12V battery source.
• Capacitor C1 is connected from positive supply to GND

Conclusion:

This 12V Battery Low Voltage Alarm Circuit is very useful.

It prevents deep discharge of battery and also it gives timely warning.

Circuit is simple and reliable which anyone can build it easily.

Therefore, this circuit is best for battery protection projects.

References:

Datasheet IC LM339