LED dot display based Battery charge level indicator circuit diagram

At many situations we need to display the amount of battery charge through some kind of indication methods like LED dot display or LED bar display. Here CG comes with a battery charge indicator circuit using LED dot display. This battery power level indicator circuit is build around LM3914 IC. It is able to sense voltage levels and is capable to drive a display of 10 LEDs in dot mode or bar mode.
We have already posted a temperature level sensor using this same IC (LM3914). This can also be used as a low battery voltage indicator circuit as it displays low voltage if you calibrate it to do so. Our circuit is most suitable for 12 volt battery status indication because we are calibrating it for 12V battery. You can alter this DIY battery level indicator circuit for monitoring and displaying other voltages also.

Circuit diagram of 12 volt battery status indicator

Components required

IC LM3914
LED x 10
Resistors (56kΩ, 18kΩ, 4.7kΩ)
Potentiometer (10kΩ)

Working of the circuit

Here LM3914 display driver IC is used to convert the battery voltage to indicate LEDs.

It is basically a milli volt measuring IC which is able to convert a varying milli volt input into a corresponding LED indication like a linear analog display.

The IC LM3914 can operate with a wide range of supply voltage (3V to 25V DC). We can control the brightness of LED by programming via an external resistor. The outputs pins of LM3914 are compatible for both TTL and CMOS.

Block diagram of LM3914

The 4.7kΩ resistor connected between pins 6,7 and ground is used for controlling the brightness of LEDs.

56kΩ resistors and 10kΩ potentiometer forms a voltage divider network, in which potentiometer is meant for the calibration of our display circuit.

Our circuit is designed to monitor battery levels between 10.5V to 15V DC.

Calibration of battery level indicator circuit:

Set up the circuit and connect a 12V DC supply to the input.

Then adjust the 10KΩ potentiometer to see the 10th LED glow (in dot mode) or LEDs up to 10 glow (in bar mode).

Now decrease the voltage in step by step up to 10.5 volts, then only LED1 will glow.

To select dot mode or bar graph mode a switch is given at the 9th pin. When switch is closed, pin 9 of the IC gets connected to the positive supply, then bar graph mode is enabled.

Open the switch to enable dot display mode.

Other usages of this circuit

With slight alteration, the circuit can be used to monitor other voltage ranges.

For this just eliminate the resistor R3 and connect the high voltage (less than 25V) to the input and adjust the potentiometer until the 10th LED glows (in dot mode).

Now connect a low voltage at the input after removing high voltage. Then connect a high value potentiometer at the 4th pin, adjust it until LED1 glows alone.

Disconnect the potentiometer, measure the resistance of the pot using a multimeter. Then connect a resistor in place of potentiometer.

That’s all; now your new voltage monitor is ready…!

Pinout

LM3914
LED

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