Definition
The lithium-ion battery pack, also known as the battery module, is a manufacturing process for lithium-ion batteries. It involves packaging, encapsulating, and assembling multiple lithium-ion cells by connecting them in series and parallel. The process also considers factors such as mechanical strength, thermal management, and Battery Management System (BMS) compatibility.

Key technologies in the pack process include overall structural design, welding and processing control, protection levels, and active thermal management systems. When two or more cells are connected in series or parallel to form a specific shape as per customer requirements, it is referred to as a pack.

Components of a Battery Pack
The battery pack mainly consists of single battery modules, electrical systems, thermal management systems, boxes and BMS, etc.

Prismatic Battery Pack Structure Diagram

• Battery Modules: If we compare the battery pack to the human body, the modules are the "heart," responsible for storing and releasing electrical energy.
• Electrical System: The electrical system consists of connecting copper busbars, high-voltage harnesses, low-voltage harnesses, and other electrical protection devices. The high-voltage harness acts as the "artery," continuously delivering electrical energy to the end loads, while the low-voltage harness serves as the "nervous system," transmitting detection and control signals in real-time.

Energy storage high-voltage wiring harness

• Thermal Management System: The thermal management system includes air-cooling and liquid-cooling methods, with liquid cooling further divided into cold plate liquid cooling and immersion liquid cooling. The thermal management system functions like an air conditioner for the battery pack. Since the battery generates heat during discharge, the system ensures the battery operates within a reasonable temperature range to extend its cycle life. A system temperature difference of ≤5°C is generally required.
• Battery Pack Case: It is mainly composed of the case body, cover plate, metal brackets, panels, and fixing screws, functioning as the "skeleton" of the battery pack. It provides support, mechanical impact resistance, vibration resistance, and environmental protection.

Battery pack case body

• BMS (Battery Management System): The BMS can be seen as the "brain" of the battery. It measures parameters such as voltage, current, and temperature and includes balancing functions. The BMS can also transmit data to the Manufacturing Execution System (MES).

Characteristics of Battery Pack

• The lithium battery pack requires high consistency in capacity, internal resistance, voltage, discharge curve, and lifespan among the cells.
• The cycle life of a battery pack is lower than that of a single battery cell.
• The pack must be used under specified conditions, including charging/discharging currents, charging methods, and temperature.
• After forming the pack, the voltage and capacity of the battery increase significantly, necessitating protection for charge balancing, temperature, voltage, and overcurrent monitoring.
• The battery pack must meet the designed voltage and capacity requirements.

How to ensure that the battery has a high degree of consistency?

This requires the use of specialized battery charge discharge test equipment to sort the battery capacity and screen its performance. By performing charge and discharge tests on each lithium battery, the computer records the data of each test point, and thus obtains the capacity and internal resistance of each battery, and determines the quality grade of the lithium battery. The battery can quickly and accurately evaluate the capacity and performance of the battery through efficient cycle charge and discharge tests.

Methods of Pack Formation

▶Series and Parallel Configuration:

The battery module is formed by connecting individual cells in series and parallel. Parallel connections increase capacity while keeping the voltage constant, while series connections increase voltage while keeping the capacity constant.

• For example, if the cell voltage is 3.2V, connecting 15 cells in series results in a 48V output, known as series boosting.
• For example, if the cell capacity is 50Ah, connecting two cells in parallel results in a 100Ah output, known as parallel expansion.

▶Cell Requirements:

Based on design requirements, select the corresponding cells. The batteries used in parallel or series must be of the same type, model, and have similar capacities, internal resistance, and voltage, with differences not exceeding 2%. Regardless of whether soft-pack batteries or cylindrical batteries are used, multiple cells need to be combined in series.

▶Pack Process:

The pack process can be achieved through two main methods:

• Laser welding, ultrasonic welding, or pulse welding. This is the common method due to its reliability, although it makes cell replacement difficult.

Handheld/Automatic Fiber Laser Welding Machine

• Contact with elastic metal sheets. This method does not require welding, making cell replacement easier but may lead to poor contact.

Considering production yield, efficiency, and the internal resistance of connection points, laser welding has become the preferred choice for many battery manufacturers.

Acey New Energy is specialized in researching and manufacturing of high-end equipment for lithium-ion battery cell production and pack assembly. They can not only provide cheap and best automatic laser welding machine for lithium ion batteries, but also provide one-stop solutions for lithium battery pack assembly. In addition, they also have a professional engineering team that can provide free online technical support and guidance.

Understanding Battery Pack Technical Parameters

▶Combination Mode: 1P24S

"S" stands for series-connected cells, and "P" stands for parallel-connected cells. 1P24S indicates 24 cells in series and 1 cell in parallel, resulting in a rated voltage of 3.2V * 24 = 76.8V.

The rated capacity of a battery is the amount of energy it can store and discharge under specified working conditions over time. It is the product of discharge current (A) and discharge time (h). Therefore, 280Ah indicates that the battery can continuously discharge at a maximum rate of 0.5C for 2 hours.

Rated energy (Wh) = nominal capacity (Ah) * nominal voltage (V), so the total energy that a battery can release is related to both capacity and voltage.

The above is a detailed analysis of the energy storage lithium battery Pack. If you are new in lithium ion battery industry, and want to build your own lithium ion battery production line or lithium ion battery pack assembly line, then ACEY, which adheres to strict quality control and thoughtful customer service, will be your best helper on the road to success!