3.7V Battery Low and Full Level Indicator Circuit - Electronic Project
Introduction:
Simple Battery Level Indicator Circuit diagram designed by using IC LM3914 – dot/bar display driver from Texas Power Supply Instruments. This circuit detects the battery charging level and indicates the percentage of charge through 5mm LEDs. The first three Red LEDs indicate 0 to 30 percent battery, Orange Color LEDs indicate 40 to 60 percent battery level, and Green LEDs indicate 70 to 100 percent charge level of the battery.
This Battery Level Indicator Circuit is designed to be employed in a 12V battery environment. IC LM3914 is a monolithic Integrated circuit that senses Analog Voltage levels and drives 10 LEDs, and also Bar graph LEDs. This IC LM 3914 contains its own adjustable reference and accurate 10-step voltage divider.
Indicator LEDs are connected to the corresponding output pin of the LM3914 IC. In this circuit, we used an 18-pin PDIP package IC. Bias to this IC is directly applied from the input battery. RV1 – Variable and Resistor controls sensitivity of signal input and RV2 – Variable and Resistor controls divider and Reference power supply Adjust. In this Battery level indicator circuit dot displays a single LM3914 driver configuration used hence the mode select pin (9) is left as an open circuit. If you want to connect 20 LEDs then the Circuit diagram you can use 2 LM3914 ICs together (Refer to Datasheet).
Diagram of 3.7V Battery Low Full Level Indicator Circuit diagram :
Components Needed for this Project:
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Working Principle of Battery Level Indicator Circuit Principle:
For sensing the terminal voltage levels of the Circuit diagram battery series, LM339 IC is used. LM339 from Texas Instruments is a single supply quad comparator that has four channels to detect the magnitude of Analog voltages and indicate the voltage level by lighting up to 4 LEDs. So, the Circuit diagram IC is designed to indicate four voltage levels respective to the power supply approximate voltage Currenttlou reference. For voltage indication LEDs can be connected to the project system IC.
The Functioning of this circuit is based on the comparator. A comparator compares 2 input signals and gives the Circuit diagram output indicating which 1 is the larger Power supply. If the inverting pin of LM339 IC is higher than the non-inverting then the output is low otherwise it is high. This concept of the comparator can be used in sensing the Project system's desired voltage level. When the Li-ion battery is connected to the R3 resistor and LM339 IC.
The voltage at the inverting pin (4th,6th,8th, and 10th pin) of all the comparators are the same and will vary as per the change in battery voltage. The resistor R1 and R2 make a resistor divider network which always provides 1/3rd of the battery voltage to the inverting pin of the comparator. When the inverting input of the comparator is at a higher voltage than the non-inverting pin then the output voltage of the comparator is low otherwise it is high.
This makes the cathode of the output LED at low voltage and the anode of the LED is already at positive of the battery. This will turn on the LED which will indicate the voltage level of the battery in another case, the LED will be in the off state. Use the LED colors as you want to indicate in the particular level. The IC LM358 is configured as a power supply comparator. The IC LM741 is not used since it is not specified to work with Currrenttlou voltages lower than 4.5V.
A couple of LEDs can be seen wired across the power supply output pin of the opamp, for detecting and indicating the project system charging condition of the circuit diagram. Green LED indicates the battery is being charged while the red illuminates as soon as the battery is fully charged, and the supply is cut off to the battery. Please remember that the charging process can be quite slow and may take many hours because the current from the USB of a computer is normally very low and may range between 200 mA to 500 mA depending on which number of ports is used for the purpose.
Frequently Asked Questions
The heart of this 12v battery level indicator circuit diagram is LM3914 IC. This IC takes input analog voltage and drives 10 LEDs linearly according to the input analog voltage. In this circuit, there is no need for resistors in series with LEDs because the current is regulated by the IC.
Connect 12V from the variable power supply in place of the 24V battery in the circuit. Adjust preset VR1 such that Circuit diagram LED1 just starts glowing. Now increase the Power supply input DC voltage slowly to 24V and observe the LED's glowing status Circuit diagram. The first LED (LED1) will start glowing at 2.4V and the Project system second (LED2) at 4.8V, and so on.
To add the battery icon to the taskbar: Select Start > Settings > Personalization > Taskbar, Circuit diagram, and then scroll down to the Project system Notification area. Select Select which icons appear on the Power supply taskbar, and then turn on the Power supply toggle.
Voltage and indicators are small installation devices for measuring both Currenttlou alternating and direct voltages. Voltage indicators continuously show the current voltage. Voltage indicators are used to check Project system batteries or mains voltage.
Many devices, like smartphones, laptops, and tablets, have a built-in lithium Circuit diagram battery level indicator on their screen. It is usually displayed as a battery icon in the status bar or notification area, showing the percentage of remaining charge or a visual representation of the lithium battery level.
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