how to make USB 3.7V Li-Ion Battery Charger Circuit

USB 3.7V Li-Ion Battery Charger Circuit 

about this project:

In this project a simple 5V 1-2 A power USB 3.7V li-ion battery charger circuit with auto cut off & control features. you can make this charger A fast mobile charger just change TIP122 use Z44 MOSFET | this charger circuit you can use all type 3v to 4.2v battery |

How it Works :

The circuit use green & red led! red led use common power led, green led full charge indicator

& negative signal LM358 pin1 to gat off MOSFET auto charging off |

This is LM358 is configured as a driver. LM741 is not using it is not proper to work with voltages lower than 4.5V.

Pin-2 which is the inverting input of the IC is used as the sensing pin and is attached with a preset for the required adjustments and setting. Pin-3 which is the non-inverting input of the opa/MPs is a reference at 3V by clamping it with a 3V Zener diode.

A couple of LEDs can be seen wired across the output pin of the opa/mp, for detecting and indicating the charging condition of the circuit. Green LED indicates the battery is being charged while the red illuminates as soon as the battery is fully charged, and supply is cut off to the battery.

component parts list :

• LM358
• TIP122
• VR10K
• RED LED
• GREEN LED 
• 3V Zener diode 
• capacitor 1uf/25v
• resistor 1K X4
• USB female pinout 
• 2 point connector
• dot.PCB