1 What is the battery Pack?

Lithium-ion battery PACK, also known as battery module, is a lithium-ion battery production process, referring to multiple lithium-ion monomer cell groups connected in parallel and series, and consider the mechanical strength of the system, thermal management, BMS matching and other issues.

Its an important technology is reflected in the overall structural design, welding and processing process control, protection level, active thermal management system. If two batteries are connected in series or parallel and formed into a specific shape according to customer requirements, it is called PACK.

2 Components of battery PACK

The important components of Yuli battery PACK include five parts: single battery cell module, electrical system, thermal management system, Boxes, and BMS.

▷ Battery Module: If you compare a battery pack to a human body, the module is the "heart", responsible for storing and releasing electrical energy.

Yuli lithium battery module

▷ Electrical Systems: It is mainly composed of connecting copper plate, high-voltage wiring harness, low-voltage wiring harness and electrical guarantee devices. The high-voltage harness can be regarded as the "artery and blood vessel" of the battery PACK, which continuously delivers battery power to the end load, while the low-voltage harness can be regarded as the "neural network" of the battery PACK, which transmits real-time detection signals and control signals. 

Energy storage high voltage harnesses

▷ Thermal Management System: Thermal management system mainly has two ways: air cooling and liquid cooling, while liquid cooling can be divided into cold plate liquid cooling and immersion liquid cooling. Thermal management system is equivalent to installing an air conditioner to the battery PACK. The battery will generate heat in the discharge mode, and to ensure that the battery works in a reasonable ambient temperature and enhance the battery cycle life, the system temperature difference is generally required to be ≤5℃

Air-cooled systems exist in a variety of assembly type core components are mainly compressors, fans, heat exchanger and so on.

▷ Boxes: It mainly consists of box, box cover, metal bracket, panel and fixing screws, which can be regarded as the "skeleton" of the battery PACK, playing the role of support, resistance to mechanical impact, mechanical vibration and environmental protection.

Yuli battery Pack housing

▷ BMS：Short for "battery management system", the battery management system can be compared to the "brain" of the battery. Yuli BMS mainly responsible for measuring the battery's voltage, current, temperature and other parameters, as well as equalization and other functions. The data can be transmitted to MES.


Yuli BMS board

3 Characteristics of battery PACK

▷ PACK lithium battery packs require batteries with a high degree of consistency (capacity, internal resistance, voltage, discharge curve, life);

▷ The cycle life of a battery pack PACK is lower than that of a single cell;

▷ Use under limited conditions (including charging and discharging current, charging method, temperature, etc.);

▷ The battery voltage and capacity ‍ are greatly increased after the lithium battery pack PACK is molded, and it must be protected and monitored for charge equalization, temperature, voltage, and overcurrent;

▷ The battery PACK must meet the voltage and capacity requirements needed for the design.

3 Characteristics of battery PACK

▷ PACK lithium battery packs require batteries with a high degree of consistency (capacity, internal resistance, voltage, discharge curve, life);

▷ The cycle life of a battery pack PACK is lower than that of a single cell;

▷ Use under limited conditions (including charging and discharging current, charging method, temperature, etc.);

▷ The battery voltage and capacity ‍ are greatly increased after the lithium battery pack PACK is molded, and it must be protected and monitored for charge equalization, temperature, voltage, and overcurrent;

▷ The battery PACK must meet the voltage and capacity requirements needed for the design.

4 PACK methodology

▷ Series-Parallel Composition: Battery module consists of single cells connected in series by parallel. Parallel connection increases the capacity and the voltage remains unchanged, while series connection multiplies the voltage and the capacity remains unchanged.

For example, if the voltage is 3.2V, and 15 of them are connected in series to have 48V, it is series boosting;

And the capacity of 50Ah core, two parallel connection up to have 100Ah, is parallel expansion.

▷ Requirements Of Battery Cell: Select the corresponding battery cell according to your design requirements, the parallel and series connection of the battery requires the same type, the same model, capacity, internal resistance, voltage value difference is not more than 2%. Regardless of whether it is a soft-packed battery or a cylindrical battery, it needs to be combined in multiple strings.

▷PACK Process: The PACK of the battery is realized in two ways, one is through laser welding or ultrasonic welding or pulse welding, which is the commonly used welding method, the advantage is that the reliability is better, but it is not easy to replace. The second is through the elastic metal sheet contact, the advantage is no welding, battery replacement is easy, the disadvantage is that it may lead to poor contact.

Taking into account the production yield, efficiency and internal resistance of the connection point, laser welding is now the first choice of many battery manufacturers.

5 What does a completed pack line looks like

Lithium-ion battery pack production line refers to a series of systematic collection of equipment and processes required for the production of Li-ion battery packs.

Yuli battery PACK includes 6 core links, including cell manufacturing, cell testing, cell grading, cell assembly, packaging and quality inspection. Among these links, cell manufacturing and cell assembly are the most central, and they directly affect the performance and quality of lithium battery pack.

▷ Cell Manufacturing: It is the first part of the production line, which can be further divided into preparation of positive and negative electrode materials, cell molding, core liquid injection and cell maturation.

Cell molding is the most critical step, and there are methods such as coil molding, laminated molding and press molding, which determines the shape and size of the cell and directly affects the performance and life of the cell.

Different molding methods are suitable for different lithium battery products, depending on the situation.

▷ Cell Testing: This process is mainly to screen out the cells with unqualified quality to ensure the smooth running of the subsequent production process. It mainly includes battery cell capacity test, battery cell internal resistance test and battery cell temperature test, etc. These tests can help manufacturers understand the performance of battery cells. These tests can help manufacturers understand the performance of the batteries, identify problems in time and make adjustments and optimizations.

6 Exploring the future prospects of lithium battery packs

As the market for energy storage batteries continues to expand, Yuli PACK production lines are being refined and improved to enhance the performance and quality of battery packs. When automation becomes widespread, Yuli shift from a labor force to a technical level, working on parameter matching as well as battery pack design, and leaving the rest to the machines with our full automatic production lines.

In the future, the technical direction of Yuli lithium battery pack production line mainly includes the following aspects:

▷Intellectualize: Through the introduction of artificial intelligence, Internet of Things and other technologies, the automation, intelligence and informationization of the production line are realized to improve production efficiency and product quality.

▷Greening: through the use of environmentally friendly materials, energy saving and emission reduction and other measures to achieve the green and sustainable development of the production process.

▷Personalized：According to the needs and requirements of different customers, realize the personalized customization and service of the production line, and improve customer satisfaction and loyalty.

▷Securitize: through strengthening safety management and risk control, guarantee the safety and stability of the production process.

7 How to read battery PACK technical parameters


Parameters example

▷ Combination: 1P24S

S stands for series cell, P stands for parallel cell, 1P24S means: 24 series and 1 parallel. The voltage is multiplied after series connection, and the rated voltage is 3.2*24=76.8V.

▷ Rated Capacity：280Ah

The rated capacity of a battery is the capacity of a battery that can continue to work for a long time under rated operating conditions. The rated capacity of the battery, C, unit ampere-hour (Ah), which is the product of the discharge current ampere (A) and discharge time hours (h). So 280Ah means that the battery can be discharged for 2h at a maximum multiplication rate of 0.5C.

▷ Energy Rating：21.504KWh

Rated Energy (Wh) = Nominal Capacity (Ah) * Nominal Voltage (V), which also means that the total energy put out by a battery is related to both capacity and voltage.

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