General description This 5 Hole 21700 Li-Ion Battery Case Box is designed for assembling and repairing battery packs, specifically compatible with Zhipu Hongsong Jingmi 18V Lithium Batteries. Please note that this product is a shell only and does not include batteries. It is intended for users who are knowledgeable about battery performance and have practical experience in battery assembly. Technical specifications Holds 5 pieces of 21700 Li-Ion batteries PCB features built-in IC for cell voltage detection Protection features: Overheat protection, overvoltage protection, undervoltage protection, overcurrent protection, overcharge protection Color options for PCB: Blue, Green, Red, etc. (random color) Material: Plastic Measurement allowed error: +/- 1-3 cm Installation For new cores: Ensure that a group of 21700 power lithium battery cores is equipped with resistance and capacitance to equalize their voltage. For old batteries: Test the voltage at both ends of each cell and charge them