Introduction to Connection System (CCS)

Cell Connection System (CCS), Its main function is to enable series and parallel connections of cells, as well as voltage and temperature sampling within the battery module.

The CCS is primarily composed of electrical trays, acquisition lines, fuses, busbars, and other related components. It is a modular system that highly integrates four key functions—signal acquisition, temperature monitoring, structural support, and electrical connection—making it an indispensable component of the battery pack.

CCS Components and Classification

1. Electrical Tray

Types: Thermoformed, Injection-molded, Hot-pressed
Example: Thermoformed Tray

• Material: Commonly PC

• Process: Sheet extrusion + thermoforming + die cutting

• Structure: Typical wall thickness 0.5 mm

• Function: Secures busbars and acquisition lines, provides insulation and protection

2. Acquisition Line

Types: FPC, Wiring Harness, PCB
Example: FPC

• Material: Insulation film (commonly PET or PI), reinforcement board FR4

• Key Process: Etching

• Structure: 25 μm PI substrate + 35 μm copper foil + coverlay; total thickness 0.12–0.18 mm

• Function: Voltage acquisition, temperature detection, and signal transmission

• Note: In addition to FPC, the market is continuously introducing new low-cost technologies such as FDC and FCC

3. Busbar

Types: Aluminum busbar, Composite busbar
Example: Aluminum Busbar

• Material: Al1060 (O state and H24 temper)

• Process: Stamping

• Structure: Thickness ≥1 mm, flatness ≤0.2 mm

• Function: Connects battery cells in series and parallel, transmits current within the power battery

Forms of CCS Interconnections

1. Wiring Harness

• This was one of the earliest forms of interconnection.

• Advantages: Established technology.

• Disadvantages: Occupies a large space, requires additional fixation, and has low production efficiency.

2. PCB Form

• Uses conventional rigid PCBs for connections.

• Advantages: High reliability, simple and efficient.

• Disadvantages: Limited advantage in weight reduction.

3. FFC Form (Flexible Flat Cable)

• Flexible Flat Cables (FFC) are flat cables composed of multiple copper strands twisted and pressed together, wrapped in insulating material.

• Advantages: Highly flexible, can be freely folded or bent, thin profile, compact size, simple to connect and remove, and effective EMI shielding.

4. FPC Form (Mainstream Form, High Market Share)

• Flexible Printed Circuits (FPC) are high-reliability printed circuits made from polyimide (PI) or polyester films as the substrate.

• Advantages: High wiring density, lightweight, thin, excellent bendability.

• Note: FPC is currently the mainstream solution and dominates the market due to its compact size and flexibility.