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The entire production and assembly process of lithium battery packs
2026-04-25
With the rapid development of the lithium battery industry, custom Battery Packs are widely applied in electric mobility, energy storage equipment, consumer electronics, industrial machinery and other fields. The standardization and refinement of lithium battery pack production and assembly directly determine product safety, stability and service life. Below is the complete production and assembly process of lithium battery packs from raw cells to finished products.
1. Cell Sorting
Professional testing equipment is used to inspect key parameters of lithium cells, including voltage, internal resistance and capacity. Cells are grouped and matched based on consistency standards. This avoids unbalanced charging and discharging, shortened service life and potential safety hazards caused by excessive performance differences between cells, and lays the foundation for overall battery pack consistency.
Formal assembly can only start after cell sorting and grouping are completed.
2. Cell arrangement and combination
Cell arrangement and combination refers to the precise arrangement of sorted 18650/21700 cells in a bracket according to the design drawings, ensuring that the positive and negative directions of the cells are consistent and the spacing is even, avoiding cell displacement and collision, forming a regular cell array, and laying a solid foundation for subsequent spot welding connections.
3. Spot Welding
Spot welding is a critical process for cell electrical connection, which directly affects connection reliability, internal resistance consistency, high-current discharge stability and long-term cycle life of battery packs.
By using a high-precision automatic spot welding machine, a large current is instantly released to melt and bond the nickel sheet with the positive and negative poles of the battery cell, forming a low resistance electrical connection and avoiding errors.
After welding, strict quality control is implemented with 100% visual inspection and sampling tests. Visual inspection checks for cold solder, over-welding and nickel strip damage. Sampling tests verify welding resistance and connection strength. Non-conforming products are isolated immediately for rework; irreparable units are scrapped to prevent defective products from flowing into subsequent processes.
4. BMS Welding
By using soldering or spot welding technology, the BMS protection board is connected to the battery pack, enabling the battery pack to have intelligent management functions such as overcharging, overdischarging, overcurrent, short circuit, and temperature protection.
If problems such as virtual soldering and polarity errors are found, immediately isolate and handle them to prevent unqualified products from flowing into the next process.
5. Semi-Finished Product Testing
Use a professional battery comprehensive tester to automatically detect the voltage and internal resistance of the battery pack, as well as the BMS protection function (overcharge, overdischarge, overcurrent trigger sensitivity), to ensure normal charging and discharging functions, reliable protection mechanisms, and to identify potential hazards such as virtual soldering and protection board failure in advance.
Qualified products: transferred to the next process
Unqualified products: fully recorded and returned to the maintenance department for inspection and rework
6. Insulation isolation
Insulation isolation is the use of insulation materials such as barley paper, red light paper, PVC film, etc., to physically wrap and cover the positive and negative end faces and exposed parts of the battery cell group, preventing external short circuits and improving structural stability. Accurately cut the insulation sheet according to the arrangement shape of the Battery Cells, and manually or automatically apply it to the designated area to ensure that the edges are not raised or displaced.
Any uneven, missing or damaged installation found during full inspection shall be immediately removed and replaced by a dedicated person. Components that cannot be repaired shall be scrapped to ensure the integrity and reliability of the insulation layer.
7. Aging Test
Aging testing is a key procedure to verify the long-term stability of finished battery packs.
Assembled semi-finished battery packs are placed in a constant-temperature aging cabinet and operated with professional charge-discharge equipment. Simulated real working conditions through cyclic charging and discharging stabilize battery capacity, internal resistance and BMS protection performance. Real-time monitoring of voltage, temperature and capacity data is conducted throughout the test.
Approved products: proceed to the next process
Non-conforming products: recorded and returned to the repair department for further analysis
8. Shell installation
Shell installation is the precise placement of the semi-finished battery pack that has undergone aging testing into a customized shell for fixation, ensuring a sturdy structure and reliable sealing, and conducting a full inspection after assembly. If non-conforming products with damaged or improperly installed shells are found, they should be immediately disassembled, reworked, or scrapped.
9. Final Pre-Shipment Testing
Finished product testing is a comprehensive evaluation of the performance, safety, and environmental adaptability of battery packs, with a focus on detecting overcharge, overdischarge, short circuit, overcurrent protection functions, as well as charge discharge cycle performance, high and low temperature adaptability, to ensure that the product meets industry standards and customer needs.
Passed: proceed to packaging
Failed: recorded and returned to the repair department for further analysis
10. Packaging
We use an anti-static and anti-collision packaging scheme, with cushioning foam attached internally and wear-resistant cardboard boxes used externally.
About Pyroxene
Pyroxene is a customized lithium battery pack supplier with over 15 years of experience, designed to meet specific needs for a wide range of applications from electric bicycles to medical devices, industrial equipment, and robots.
Our battery pack has reliability, performance, and safety:
Customized design: Tailored according to specific voltage, capacity, and energy requirements.
High quality batteries: from well-known manufacturers such as LG and Samsung.
Strict testing: Comprehensive security and performance testing to meet industry standards.
Scalable production: flexible manufacturing capabilities suitable for both small and large orders.