3 Electrical Connection & BMS

Electrical connections are made between the cells to form the required series and/or parallel configuration using busbars, achieving the target module voltage and capacity. This stage also includes integration of the Battery Management System (BMS), typically through the Cell Supervising Circuit (CSC) and sensing components. Voltage and temperature sensors are connected to the cells or busbars to enable monitoring. Laser or ultrasonic welding is commonly used for reliable, low-resistance joints. In some designs, resin dispensing or potting is added to protect critical electrical components and ensure long-term durability. 

Key sub-processes:

Cell Contacting: This involves precisely placing busbars or other current collectors onto the cell terminals and then creating permanent, low-resistance electrical joints, most commonly through laser, ultrasonic or resistance welding. This forms the main series/parallel connections between cells.

Welding of Cell Supervising Circuit (CSC): The sense wires from the Cell Supervising Circuit or Flexible Printed Circuits (FPCs) are connected to appropriate points on the cells or busbars to monitor individual cell voltages and temperatures. This often involves micro-welding or soldering techniques. This is usually performed as part of the sub-assembly rather than on the main module production line

Resin Dispensing: In some module designs, after all electrical connections are made, specific areas of the internal assembly are filled with an insulating and protective resin. This enhances mechanical stability, protects against vibration and moisture, and improves electrical insulation.