Cells Contact System (CCS)

Reliable Connectivity for Lithium Battery Packs

Lithium battery packs are the core power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs). Within these packs, the Cell Contact System (CCS) serves as a critical electrical connection module, seamlessly linking individual battery cells and the Battery Management System (BMS).

At Astrolkwx, we understand the vital role of a robust and efficient CCS in ensuring the performance, safety, and longevity of EV and HEV battery systems.

Functions of a Battery Cell Contact System

The Cell Contact System, also referred to as a cell contacting system, is meticulously designed to accommodate the specific series and parallel configurations of lithium-ion battery cells. By replacing extensive wiring harnesses, the CCS significantly optimizes space within the battery pack. Typically employing thermal lamination or blister tray riveting for secure assembly, it offers a streamlined and dependable connection solution.

Structures of a Battery Cell Contact System

A battery cell contact system typically comprises:

• Signal Collection PCBA: This Printed Circuit Board Assembly can be based on various flexible or rigid substrates such as FPC (Flexible Printed Circuit), RF4 PCB, FDC (Flexible Dielectric Circuit), FFC (Flexible Flat Cable), or traditional wiring cables, tailored to the application requirements.
• Insulation Films: One or two layers of insulation film, typically made of black or yellow PET (polyester), are strategically placed on the top and/or bottom of the assembly. These films provide essential electrical insulation between the battery cells and the battery pack’s metallic enclosure, preventing short circuits. In dual-film configurations, the PCBA is often sandwiched and thermally laminated. Single-film designs typically involve thermal riveting of the flexible PCBA with the insulation film using blister trays.
• Copper Busbars: Multiple copper busbars are integrated into the CCS module, their quantity and layout determined by the specific arrangement of the battery cells. While copper is the standard material, aluminum or nickel-plated copper may be used depending on the electrode material of the battery cells. These busbars facilitate the serial and parallel connection of the battery cells, enabling efficient power transfer. Notably, holes are incorporated into the copper busbars to facilitate subsequent laser soldering by the battery pack system manufacturer to the battery cell electrodes. A connection between a copper busbar and a nickel sheet on the CCS module enables accurate temperature monitoring of the battery cells.

Key Components

• PCBA (Printed Circuit Board Assembly): Utilizing either FR4 PCB or, more commonly, flexible PCB (FPC), the PCBA serves as the foundation for mounting various surface mount devices (SMDs).
• NTC Thermistors: These negative temperature coefficient resistors are crucial temperature sensors. Surface-mounted on the PCBA, often within специально designed hollow areas of the nickel sheets, they exhibit a decrease in resistance with increasing temperature. This characteristic allows the BMS to accurately monitor temperature fluctuations within the battery cells. The BMS sends a current through the NTC; changes in temperature cause variations in this current, which the BMS analyzes to assess the thermal state of the battery pack.
• Nickel Sheets: Custom-engineered for the CCS, these sheets feature a hollow end for surface mounting and adhesive fixation on the FPC during the flexible PCB assembly process. The opposite end is later connected to the busbar via laser soldering or screw riveting, facilitating both electrical connection and temperature sensing.
• Connectors: Located at the ends of the FPC, these surface-mounted components provide a reliable interface for communication and signal transfer between the CCS and the BMS.
• FPC (Flexible Printed Circuit): Leveraging mature technology and decreasing manufacturing costs, FPC-based CCS solutions are increasingly prevalent. Typically constructed from polyimide (PI) with adhesive and rolled annealed copper, the FPC used in CCS applications is generally single-layer due to the static nature of its application. The manufacturing process often employs the toll-to-toll copper foil method, preferred for its higher yield rate, consistent dimensional tolerance, and stable performance.

Cells Contact System (CCS) Characteristics

Battery Power Transmission: Efficiently conducts electrical current between battery cells.
Signal Collection: Enables precise voltage and temperature monitoring of individual cells.
Cell Protection: Contributes to the overall safety of the battery pack.
Lightweight: Minimizes added weight to the battery system.
Compact: Optimizes space utilization within the battery pack.
Automated: Facilitates efficient and scalable manufacturing processes.

Astrolkwx is committed to providing high-quality, reliable CCS solutions tailored to the specific needs of your EV and HEV battery pack designs. Contact us to discuss your requirements and explore how our expertise can contribute to your success.