3.7 Volts Battery Low and Full Level Indicator Ciruit

In this project 3.7 volts battery low full indicator, we are going to make a very simple battery level indicator. This indicator circuit is for 3.7 volts indicator. We have designed this circuit with few components at home with easy available components. These components can either be collected from an old circuit or can be purchased from an electronics shop easily.

Cricut Diagram

3.7v Battery low full indicator

Components required 

  • Transistor – BC547 x1
  • Resistor – 1K x2
  • Resistor – 220 ohm x3
  • PN-Junction Diode – 1N4007 x1
  • LED – 3V x2 (Red for Low charge indication and Green for Full charge indication)
  • Battery – 3.7V and 3V

Step 1.

First of all, connect 1K resistor to Base and emitter pin of the transistor as shown in the picture given below.

3.7 volts battery indicator

Step 2.

In second stop solder 220-ohm resistor to the collector pin of the transistor as shown in the picture.

3.7v battery level inidicator

Step 3.

In this step Connect 1 kilo-ohm resistor with the second point of the 220-ohm resistor.

3.7 v battery low full indicator

Step 4.

In step 4 connect  Diode IN4007 with the base point of Transistor as we have connected in the picture given below. Connect the cathode point of diode with the base point of the transistor.

3.7 V battery full low indicator

Step 5.

connect – point of green led with Diode – point and +ve point of led green led with 1k resistor as shown below.

3.7v battery level indicator

Step 6.

solder – point of red LED to -ve point of the diode and + point of red led with collector point of the transistor as we have shown in the diagram given below.

3.7V battery level indicator


Our circuit has been completed Now we check it by connecting battery. Connect +ve of 3.7 Volts battery to +ve point of green LED and – point of 3.7V battery to emitter point of the transistor as we have connected in the circuit given below.

3.7V battery Charge Indicator

When you will connect 3.V battery then Red LED will glow completely if the battery will be low. Green Led will glow when the battery will be charged above 3.2V.

Its tested Circuit its complete construction points can be seen in the video given below.

Thank you

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