Summary: This circuit shows the charging status, the red light is flashing, the green light is almost full, and the green light is fully charged. As long as you have 12V power supply, do not install the battery after the circuit is connected, adjust the adjustable resistor in the lower right corner to make the battery output terminal 4.2V, and then adjust the adjustable resistor in the lower left corner to make the LM358 third pin 0.16V. It can be, the charging current is 380mA, super fast, three parallel diodes are step-down, to prevent LM317 overheating, and the LM317 must be equipped with a heat sink. The triode in the figure can be any type. The 12V grounding is black triangle, the battery grounding is the horizontal bar, and the two grounds cannot be connected together! This circuit is a senior electronic engineer of the company specially helped me to do it. It is unique. When I connect it, the measured maximum current is 480mA. I am afraid that the LM317 can't stand it, and the 2w3Ω resistance will be changed to 2w3.9Ω. At this time, the maximum current is 375mA. In fact, when the charging current is less than 80mA, the green light will be on. He said that when the charging current of the lithium battery is less than 80mA, the capacity is over 97%, so it is not too limited, otherwise it is not good. The limited current can be set by adjusting the adjustable resistance of the left lower leg. The circuit is really excellent. My 2000mA/h lithium battery is fully charged in four hours. I don't need to charge it, but the LM317 is slightly hot. He said nothing, as long as the battery ends are not short-circuited for a long time. Arrowhead Mount Cable Tie for Round Hole Arrowhead Mount Cable Tie For Round Hole,Round Hole Zip Tie,Push Mount Fixing Tie,Arrowhead Fixing Tie Wenzhou Langrun Electric Co.,Ltd , https://www.langrunele.com