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Thursday, November 24, 2022

on video Simple 3.7 volt battery charger with auto cut off


 3.7v battery charger circuit with auto cut off

3.7v battery charger circuit diagram

3.7 volt battery charger automatic

Automatic 3.7 volt battery charger circuit

18650 battery charger with auto cutoff

3.7v battery full charge indicator

3.7v battery protection circuit


In this video i'm showing how to make 3.7 volt battery charger circuit with auto cut off on Full Charge.

For that i used TL431 Shunt Regulator, it's actually a adjustable zener.

I used mosfet which remains on by supplying small positive voltage using 1k resistor.

And cut off voltage is set at reference pin1 of TL431 by using resistors from both positive & negative.

When voltage in circuit reaches to threshold point TL431 connects negative voltage from pin2 to pin3 so positive voltage at mosfet gate pin becomes zero and Mosfet turns off.

Irfz44n Mosfet

TL431 Shunt Regulator

2x  4.7k Resistors

1k Resistor

15k Resistor

5.6k Resistor

220 ohms Resistor

Red & Green Led (5mm)

Crocodile clip wires

Battery Holder



 3.7v battery charger circuit with auto cut off

3.7v battery charger circuit diagram

3.7 volt battery charger automatic

Automatic 3.7 volt battery charger circuit

18650 battery charger with auto cutoff

3.7v battery full charge indicator

3.7v battery protection circuit


In this video i'm showing how to make 3.7 volt battery charger circuit with auto cut off on Full Charge.

For that i used TL431 Shunt Regulator, it's actually a adjustable zener.

I used mosfet which remains on by supplying small positive voltage using 1k resistor.

And cut off voltage is set at reference pin1 of TL431 by using resistors from both positive & negative.

When voltage in circuit reaches to threshold point TL431 connects negative voltage from pin2 to pin3 so positive voltage at mosfet gate pin becomes zero and Mosfet turns off.

Irfz44n Mosfet

TL431 Shunt Regulator

2x  4.7k Resistors

1k Resistor

15k Resistor

5.6k Resistor

220 ohms Resistor

Red & Green Led (5mm)

Crocodile clip wires

Battery Holder


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