As a type of lithium-ion battery product, battery modules are gradually gaining attention. Today we will learn about the things to pay attention to when purchasing and customizing battery modules through application, cost, structure and information collection. Do you want to save energy and cost to buy battery modules that suits your needs? Then come and take a look at this complete guide to buying battery modules!
Standard Battery Module and Custom Battery Module
Standard Battery Module
Standard battery modules generally refer to battery modules that have been developed and designed according to industry standards, mass-produced and applied on a large scale.
Standard battery modules are usually developed to match corresponding projects. For example, electric vehicle battery modules used in electric vehicles, or energy storage battery modules used in large energy storage projects. Relative to different applications, their development and design are also different. For more information, please refer to: EV battery module vs. ESS battery module.
The advantage of standard battery modules is that the products have been developed and produced. They have been verified by the market, and no additional development costs are required when purchasing. At the same time, its disadvantages are also obvious.
The location of the battery module installation point generally needs to be determined according to the layout of the entire battery pack, and the reliability of the battery module under vibration conditions needs to be comprehensively considered. For standard battery modules, these have been determined. In addition, there are also the interface positions of the heat dissipation components and the battery information collection interface are also designed.
Therefore, when purchasing standard battery modules, you must pay attention to whether the battery module you choose can match your product. Whether it is the application, size, installation and interface of the battery module, it needs to be confirmed before purchasing.
Custom Battery Module
Compared with standard battery modules, customized battery modules have higher flexibility. You can customize a more suitable battery module according to the actual situation of the project. The main considerations for customizing battery modules are generally the following: battery cells, size, and application.
1.Battery Cells
Customized battery modules can select appropriate battery cells according to the required voltage, capacity and grouping method. High-quality battery cells that have been verified by the market and can be continuously supplied in large quantities are the best choice. This not only ensures the production of battery modules after design and development, but also allows replacement battery cells to be found during after-sales maintenance. The development and production of battery modules will not be interrupted due to the discontinuation of battery cell production.
2.Size
The size of the battery module is usually determined by the space in which it is placed. If the space is ample, the size of the battery module can be selected more widely. If the space is tight, the placement and arrangement of the battery module is very important. Reasonable layout and arrangement can allow the battery module to meet the power supply requirements while taking into account good heat dissipation, safety and structural support.
3.Application
Battery modules are mainly used in power and energy storage projects.
Power applications generally refer to electric vehicles, drones, tricycles, golf carts, yachts, etc. These projects generally have high requirements for the size, discharge rate, and seismic resistance of battery modules. Some also require real-time battery data collection. These are all things to consider when purchasing.
Energy storage applications generally refer to large, medium, and small energy storage projects, home energy storage, commercial energy storage, UPS, etc. These projects generally have high requirements for the cycle life and storage capacity of battery modules. Communication and battery data collection are also essential.
Although customized battery modules are more flexible, they may require some development costs and a longer cycle. When there are fewer customized battery modules, their production costs may be higher than those of mass production.
Battery Module Information Collection Solution
During the operation of the battery module, accurate collection of data such as voltage and temperature is particularly important for the battery management system. Battery data can directly reflect the state of the battery cell and provide a key basis for the precise control of the battery management system. If there is a deviation in data collection, the battery management system may issue wrong instructions, resulting in a shortened battery life, and in serious cases, it may also bring safety hazards.
At present, the common battery module information collection solutions on the market are generally FPC solution and wiring harness solution.
Wiring Harness Solution
The wiring harness solution refers to the connection of the wiring harness to the battery pole through the terminal to build a stable electrical path and accurately transmit power and signals. It is usually made of multiple strands of copper or aluminum wires twisted together, and the outside is wrapped with insulating materials to ensure the stable transmission of current and the safe isolation of the circuit. Equipped with NTC chips or plug-in thermistors, the battery temperature can be collected.
The wiring harness solution occupies a place in the market with its mature technology and reliable performance. Especially in some application scenarios with strict cost control and relatively slow technology updates, such as some low-speed electric vehicles and small energy storage equipment, the wiring harness solution has become the first choice of many manufacturers with its low cost and simple installation and maintenance process.
In small photovoltaic energy storage power stations in remote areas, traditional wiring harness solution can operate stably in complex and changing environments, continuously delivering electricity to local residents, and showing extremely high reliability.
However, the wiring harness solution also has obvious shortcomings. This solution has a large number of wiring harnesses connected to each other, which is complex to wire and takes up a lot of space. Once a fault occurs, it is difficult to troubleshoot.
The wiring harness solution is also divided into two types: screw fixing and laser welding due to different connection methods.
1.Screw Fixation
Advantages: Low cost. Various specifications of OT terminals are available. Convenient manual operation.
Disadvantages: Workers are prone to errors in assembly. It cannot be automated and has low production efficiency.
2.Laser Welding
Advantages: Stable signal transmission, strong current capacity. Strong and beautiful connection, high degree of automation.
Disadvantages: Slightly higher cost than screw fixing solution.
FPC Solution
Flexible Printed Circuit (FPC), also known as soft circuit board or flexible circuit board, is a highly reliable and excellent flexible printed circuit board made of polyimide or polyester film as the substrate. It is characterized by high wiring density, light weight, thin thickness and good bending.
The FPC solution integrates component assembly and wire connection, can fit closely to the surface of the battery cell, accurately and quickly collect voltage and temperature signals, and transmit them to BMS in real time, greatly improving the accuracy and efficiency of battery management. At the same time, it saves valuable space and improves the rationality of the overall layout.
However, the minimum order quantity of FPC is high, the flexibility is poor, and it is difficult to change and repair. Once made, changes must start from the base map or the compiled photolithography program. Before repairing, remove the protective film covering the surface and restore it after repairing. Its size is limited by the size of the production equipment and cannot be made very long and wide. It is easy to be damaged during assembly, and improper operation can easily cause damage to the flexible circuit. It requires trained personnel to operate.
The production process is complex and has strict requirements on raw materials, manufacturing equipment and technical personnel, which makes the cost of FPC solution high. In addition, the performance stability of FPC is easily affected in extreme environments such as high temperature and high humidity, and further optimization of materials and processes is required to cope with complex working conditions.
Wiring Harness Solution vs. FPC Solution
In summary, FPC solutions are often used in high-end electric vehicles, commercial vehicles and other projects that are not sensitive to price and are mass-produced. Screw-fixed wiring harness solutions are often used in projects that have extremely high cost requirements and require flexible disassembly. Most customers often choose the most cost-effective laser welding wiring harness solution.
Battery Module Accessories
Insulation components
When assembling battery modules, battery cell partition materials are often used. These materials are mainly used to dissipate heat, isolate heat conduction between battery cells, and have a certain degree of insulation. The following are several common insulation materials:
1.Highland Barley Paper
Advantages: Extremely low cost, easy to cut and install, reliable insulation.
Disadvantages: Extremely poor thermal conductivity, unable to assist in heat dissipation. Limited temperature resistance, easy to carbonize and fail at high temperatures. Strong hygroscopicity, insulation performance decreases in humid environments.
2.Epoxy Resin Board
Advantages: Low cost. High rigidity, can also serve as a structural support. Resistant to chemical corrosion and electrolyte penetration.
Disadvantages: Poor thermal conductivity, easy to form local hot spots. High brittleness, easy to crack under vibration environment. High temperature resin decomposes and releases harmful gases.
3.Foam
Advantages: Low cost, good flexibility, easy to install.
Disadvantages: Strong hygroscopicity, reduced insulation performance in humid environments. The thickness must reach a certain specification to achieve effective insulation, and it takes up space.
4.Aluminum Plate
Advantages: Light weight, good thermal conductivity. Aluminum plates with holes have higher heat dissipation efficiency.
Disadvantages: High cost. An additional insulating layer needs to be applied. Burrs are easily generated on the edge of the hole and pierce the diaphragm, so strict quality control is required.
5.Structural Adhesive
Advantages: Integrated design, fixes the battery cells while transferring heat and dissipating heat. Combined with aluminum plate, it can improve thermal conductivity.
Disadvantages: High cost. Difficult to disassemble after curing. High temperature may carbonize and lose viscosity.
6.Aerogel
Advantages: Ultra-low thermal conductivity, lightweight, high temperature resistance.
Disadvantages: High cost. Low mechanical strength, easy to break, need to be used with support structure. Difficult to install.
In summary, the above battery module insulation and heat dissipation accessories each have their own advantages and disadvantages. Sometimes they are used in combination according to the project situation. The insulation and heat dissipation solution of the battery module needs to balance between thermal management (longitudinal heat conduction) and thermal safety (lateral partition), and take into account the cost.
Fixed components
1.Side and End Plate
Early battery modules were mostly used in electric vehicles, so aluminum alloy end plates and side plates were often used to fix the battery cells. A battery module has two end plates and two side plates. The end plates are located at the head and tail of the battery module, and the side plates are located on both sides of the battery module, which are fixed by laser welding. They provide mechanical support and protection for the battery module, ensuring the alignment and structural integrity of the battery cells in the module. At the same time, the excellent thermal conductivity of aluminum is used to help dissipate heat.
The side plate plus end plate solution has good anti-vibration effect, and the protection and support are also very good. The disadvantages are high cost and poor flexibility.
With the development of the industry, some battery modules have cancelled the traditional side plate design. The cancellation of the side plate results in no connection between the side plate and the end plate to resist the expansion force brought by each battery cell. Therefore, in order to resist the expansion force of the battery cell, a binding strap is usually used in combination with the end plate to apply a pre-tightening force when assembling the battery module to solve this problem.
Although the binding strap plus end plate solution is not as strong as the side plate plus end plate solution, it reduces costs and improves flexibility, and has become the choice of many customers.
2.Steel Strap and PET Plastic Steel Strap
In the previous section, we talked about the use of strapping to reinforce battery modules. In this section, we will take a closer look at the advantages, disadvantages and costs of strapping made of different materials.
At present, the most commonly used strapping materials on the market are steel strap and PET plastic steel strap. Sometimes they are used in combination according to the situation. The number of strapping used will also be adjusted according to the project requirements.
The advantages of steel straps are high mechanical strength and significant tensile strength compared to PET steel straps. Good dimensional stability and high thickness accuracy. Its disadvantages are higher cost than PET steel straps, heavy weight, complex and bulky operation, and high labor costs. Relying on steel strapping buckles for locking, it is easy to form protrusions and pose safety hazards.
The advantages of PET steel straps are lower cost and lighter weight than steel straps. Safe and convenient operation, suitable for automated production lines. Excellent flame retardancy and insulation, no steel buckle design without protrusion hazards. The disadvantage is that the mechanical strength is weaker than steel straps, and it may break under extreme impact. Long-term exposure to high temperature may affect the tension.
In addition to the above two methods, when facing small energy storage projects, some customers will choose a simpler bundling method: just use bundling tape to fix it. This method is very cost-saving, but it is usually only suitable for small battery modules, with few battery cells, simple series and parallel connection, and no requirements for vibration, with additional protection or support. Coupled with the assembly method of screw fixing, it is more flexible and easy to replace and maintain.
Heating Components
Earlier we learned about the heat dissipation and insulation components of the battery module. Now let’s talk about its heating components.
We all know that lithium ion batteries have a certain operating temperature range, and low temperature environments often affect the performance of lithium ion batteries. Battery preheating technology is an important part of battery thermal management. It is a technology that allows the battery temperature to quickly rise to the optimal operating temperature when the temperature is low.
The natural heating of the battery can use the heat generated by the battery itself when it is working, discharging or charging to increase the temperature of the battery. However, this method of heating is slow and not ideal. At this time, the heating film becomes a better choice.
The heating film has a good heating effect, fast speed, and is close to the surface of the battery module. However, adding a heating film not only increases the cost of the battery module, but also requires reconsidering the design of thermal management. Therefore, customers usually consider adding a heating film when using the battery module in a specific cold environment. No additional addition is required for general use environments.
Summary
The above is the full content of this article. We analyze and compare the battery module structure, components, applications and costs, hoping to provide some help when you buy battery modules. If you have other questions, or need to customize or purchase a battery module, you are welcome to contact us at any time. Our professional technical team will definitely help you and provide you with ideal battery module solutions!
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