Battery Pack Assembly Process Series 5 - Finished Pack Assembly

• Power battery monomer (battery cell): like a combat unit soldier (basic combat mission: store and release electrical energy), responsible for storing and releasing electrical energy, is the cornerstone of the army.
• Battery management system (BMS): like a headquarters, responsible for receiving instructions, collecting information, calculating decisions, issuing orders and protection.
• Thermal management system: like a logistics support system, responsible for heating or cooling, maintaining the best combat state of the battery.
• Box cover: like a trench, protecting soldiers from the enemy (dust, liquid, etc.).
• Sensor: like a scout, responsible for collecting information.
• Wire harness and connector: like a communication and transportation system, responsible for information transmission and power transmission.
• Other components: like various materials, although not the main function, but has a significant impact on system performance.

Finished pack assembly is to form a complete "army" of various departments, materials, communications and transportation systems.

• Cleaning the box: Before assembling the box, use an industrial vacuum cleaner to thoroughly clean the inside of the box to ensure that there is no dust or debris, and focus on cleaning metal debris such as aluminum chips.
• Glue sealing: Paste a sealing strip (mostly foamed silicone) on the flange surface of the box. The flange surfaces of the box and the box cover should ensure a certain flatness to ensure the sealing between the box and the upper cover.
• Install the upper cover: Align the upper cover with the box. Generally, two workers start from the opposite corner of the battery pack and tighten it in a clockwise or counterclockwise direction with bolts to ensure that the sealant is evenly distributed.

• Bolt installation: Install the bolts to the connection position of the box and the module according to the design requirements.
• Torque control: Use a torque wrench or automated equipment to tighten the bolts to ensure that the torque of each bolt meets the design requirements.
• Marking: Mark the bolts and connection positions for subsequent inspection and maintenance.

The protection level (IP level) consists of two numbers, the first number indicates the dustproof ability, and the second number indicates the waterproof ability.

There are three main methods for testing the protection level:

• Inflation: Inflate the workpiece to be tested with the test pressure. The time of the inflation stage is adjusted by the test volume and the test pressure.
• Balance: The pressure and temperature in the test component reach equilibrium. The time required for the balance stage is related to the test volume, test pressure, and thermal properties of the workpiece.
• Detection: Measure the leakage rate of the test gas in the test volume within a certain period of time.
• Exhaust: During the exhaust stage, provide atmospheric exhaust for the test component.

Leakage rate: Pressure drop per unit time, for example 0.02 Pa/s. The leakage rate can also be defined as a flow unit, such as 4cm/min. In addition to specifying the air volume parameters (such as standard cm/min) allowed to leak under standard use conditions, a complete testing specification should also specify the pressure when the air leaks.

Leakage calculation formula:

(3) Factors affecting air tightness

• The impact of battery pack structure on air tightness:

• Problems affecting air tightness during battery pack use:

• Influence during the manufacturing process: