news test 04

What is a PACK battery pack?

First of all, we must understand the general distinction between lithium battery cells, lithium battery modules and lithium battery packs:

Battery cell: the most basic element that makes up the battery pack and battery pack, generally can provide a voltage between 3V-4V;

Battery pack: consists of a collection of multiple cells to form a single physical module, providing higher voltage and capacity;

Battery pack (pack): It is generally composed of multiple battery packs, and at the same time, a battery management system (BMS) is added, which is the last product provided to the user by the battery factory.

As the core component of PACK, battery cells are currently divided into three categories according to the shape of cells: square shell, cylindrical, and soft package (polymer battery). The positive and negative electrode pieces are packaged into the corresponding housings in different ways.

Battery module

By assembling a single cell, the cells are connected in different series and parallel through the bus bar, which can be screw locking, resistance welding, ultrasonic welding, ultrasonic aluminum wire welding and laser welding. Considering the production yield, efficiency and internal resistance of the connection point, laser welding has been the first choice for many battery manufacturers.

The composition of the PACK battery pack;                               It mainly includes battery module, mechanism system, electrical system, thermal management system and BMS parts.

Battery module                                             

If the battery pack is compared to a human body, then the module is the "heart", responsible for storing and releasing energy to power the car.                                          Mechanism system is mainly composed of battery PACK cover, tray, various metal brackets, end plates and bolts, which can be regarded as the "bone" of battery PACK, which plays the role of support, mechanical shock, mechanical vibration and environmental protection (waterproof and dustproof).                        The electrical system is mainly composed of high-voltage jumpers or high-voltage wiring harnesses, low-voltage wiring harnesses and relays. The high-voltage wiring harness can be regarded as the "large arterial blood vessel" of the battery PACK, which continuously transmits the power of the heart of the power battery system to the required components, and the low-voltage wiring harness can be regarded as the "neural network" of the battery PACK, transmitting detection signals and control signals in real time.                                                      Thermal management system There are four main types of thermal management systems: air-cooled, water-cooled, liquid-cooled, and phase change materials. Taking the water cooling system as an example, the thermal management system is mainly composed of a cooling plate, a cooling water pipe, a heat insulation pad and a heat conductive pad. The thermal management system is equivalent to installing an air conditioner on the battery pack.                                                                              

Battery management system Battery management system can be regarded as the "brain" of the battery. It is mainly composed of CMU and BMU.

CMU: Cell monitor Unit, responsible for measuring parameters such as voltage, current and temperature of the battery, as well as functions such as equalization. When the CMU measures this data, it transmits the data to the BMU through the battery "neural network" mentioned earlier.

BMU: Battery management unit.

It is responsible for evaluating the data transmitted by the CMU, and if the data is abnormal, it protects the battery, issues a request to reduce the current, or cuts off the charge and discharge path to prevent the battery from exceeding the permitted conditions of use, and also manages the battery power and temperature. According to the previously designed control strategy, the parameters and states that need to be warned are determined, and the warning is sent to the vehicle controller and finally communicated to the driver.

Process flow Battery PACK is the core energy source of new energy vehicles, providing driving power for the whole vehicle. As the core component of new energy vehicles, its quality directly determines the performance of the whole vehicle. Lithium battery manufacturing equipment is generally three kinds of front-end equipment, middle-end equipment, and back-end equipment, and its equipment accuracy and automation level will directly affect the production efficiency and consistency of products. Although the types of cells and modules are different, the composition and process flow of PACK are generally the same (not all manufacturers' process flow is the same) 

It is mainly divided into assembly process, air tightness testing process, software writing process, electrical performance testing process, etc.

Production line introduction; There are many flexible lines and press-fitting tightening in the PACK assembly process, the difficulty of automation is high and the input-output ratio is not high, so the degree of automation of the rear equipment will be lower than that of the front and middle sections, but it is compatible with cylindrical, square shell, and soft package three kinds of PACK battery packaging.

Stations that may be required for automation:

-The lower housing is automatically online

-The module is automatically put online into the housing

-Module fixing tightening

-Attach and tighten the lid

- Automatic application of A/B thermal adhesive (depending on the process)

- Automatic application of sealant (depending on process)

-Finished products rolled off the production line

In addition, some will propose that bronze plate installation and screw tightening, air tightness test, EOL test also need automatic methods, which are relatively rare and stability is difficult to guarantee.

There are two main types of operation of the rear PACK line mass production equipment: 1. AGV+ assembly trolley In the past, it was mainly used in car factories, and now battery factories are slowly pushing this model. 2. Conveyor line + pallet mode roller line/roller table friction line/multiple chain conveyor line

The above is the basic knowledge of lithium battery pack PACK.

Teabouf Eastbascienolich Ben Litt Hume Batry Parker.