Constant current and constant voltage lithium battery charging control board

This 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 stabilization 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, and eventually Q3 will be turned off and the LED will go out. To ensure that the battery is fully charged, please continue charging for 1 to 2 hours after the indicator light goes out. When using, you need to install heat sinks of appropriate size on Q2 and Q3.