This product is component without battery core. It is used to repair and batteries pack, people who are familiar with battery performance and have practical experience in battery assembly. Built-in IC detects cell voltage and current. and the number of uses! Detection and protection battery: Overheat protection, overvoltage protection, undervoltage protection, overcurrent protection, overcharge protection. PCB design may change due to changes with the supply chain and processing technology. be kindly : If you have any objection to the following two items, do not order ! 1. PCB color may be any color according to , 2.PCB design may change with the same function and performance. Preparation assembly: 1. If a new core is used, note: a. 18650 Power lithium battery core must be , b. A group of 10/20 cores must be equipped with resistance and capacitance to make their voltage the same. 2. If the old battery is repaired, test the voltage at both ends of each cell. If the voltage is different, charge each cell to the same voltage value. important: that the voltage of each cell is the same welding PCB. Different production batches, the appearance of the product may be different from the picture. Colour: random colors, 't accept the specified color Material: PCB Size: PCB board size: 90x65mm Package Contents: 1 * PCB - Battery Charging Protection Circuit Board Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.