Lithium battery constant current and constant voltage charging circuit diagram

As shown in the figure, it is a constant current and constant voltage lithium battery charging control board. In the figure, Q1, R1, W1, and TL431 form a precision adjustable voltage stabilizing circuit. Q2, W2 and R2 form an adjustable constant current circuit. Q3, R3, R4, R5, and LED are charging indication circuits. As the voltage of the charged lithium battery gradually rises, the charging current will gradually decrease. After the battery is fully charged, the voltage drop on R4 will continue to decrease, eventually causing Q3 to cut off and the LED to turn off. In order to ensure that the battery is sufficient, please wait until the indicator light turns off. Continue charging for 1 to 2 hours. When using, you need to install heat sinks of appropriate size on Q2 and Q3.