What’s Inside an Energy Storage Battery PACK? A Complete Guide

Lithium-ion battery PACK, also known as a battery module, is a core manufacturing process for lithium-ion batteries. It refers to integrating multiple lithium-ion single cells through series and parallel connections, while comprehensively solving system issues such as mechanical strength, thermal management, BMS matching, and structural protection.

The core technologies are reflected in: overall structural design, welding and processing technology control, protection level, and active thermal management system. Simply put, combining battery cells into a battery pack with specific voltage, capacity, and shape according to customer needs is called PACK.

1. Battery Module: The "energy heart" of the PACK, composed of single cells connected in series and parallel, responsible for energy storage and release, and is the core energy storage unit.
2. Electrical System: The "blood vessels and neural network" of the PACK, consisting of connecting copper bars, high-voltage wiring harnesses, low-voltage wiring harnesses, and protective devices (fuses, relays, etc.); high-voltage wiring harnesses transmit large currents, while low-voltage wiring harnesses transmit detection and control signals.
3. Thermal Management System: The "temperature control air conditioner" of the PACK, mainly including air cooling and liquid cooling (cold plate/immersion liquid cooling), which controls the working temperature difference of the battery to ≤5℃ to ensure service life and safety.
4. Case: The "protective skeleton" of the PACK, composed of the case body, cover plate, bracket, and fasteners, undertaking the functions of support, impact resistance, vibration prevention, and sealed environmental protection.
5. BMS (Battery Management System): The "control brain" of the PACK, which real-time monitors voltage, current, and temperature, and realizes cell balancing, data upload, and safety protection.

• Extremely high requirements for cell consistency (minimal differences in capacity, internal resistance, voltage, discharge curve, and service life).
• The cycle life of the battery pack is lower than that of single cells.
• Must be used under limited conditions (charging/discharging current, charging method, temperature range).
• After assembly, the voltage and capacity are greatly improved, and overcharge, over-discharge, over-current, and over-temperature protection and balancing functions must be configured.
• Must accurately meet the designed rated voltage and rated capacity indicators.

1. Series-Parallel Rules
   • Series Connection: Voltage superposition, capacity remains unchanged; example: 15 pieces of 3.2V cells in series = 48V.
   • Parallel Connection: Capacity superposition, voltage remains unchanged; example: 2 pieces of 50Ah cells in parallel = 100Ah.
2. Cell Matching Requirements: Same model, same specification, same batch, with capacity/internal resistance/voltage difference ≤2% to ensure consistency.
3. Connection Technology
   • Welding Technology: Laser welding, ultrasonic welding, pulse welding, with reliable connection and low internal resistance; laser welding is the industry's mainstream choice.
   • Elastic Contact: Welding-free and easy to replace, but prone to poor contact and high internal resistance, with low reliability.

1. Cell Manufacturing: Including positive and negative electrode preparation, cell formation (winding/lamination/stamping), electrolyte injection, and formation; cell formation determines performance and service life.
2. Cell Testing: Full-item testing such as capacity, internal resistance, and temperature to screen out defective products.
3. Cell Grading: Grouping by parameter consistency to ensure assembly quality.
4. Cell Assembly: Series-parallel connection, module integration, electrical connection, thermal management and case assembly.
5. Quality Inspection: Full inspection of electrical performance, safety, insulation, temperature control, and BMS functions.
6. Packaging and Shipping: Encapsulation, labeling, and warehousing of qualified products.

1. Intelligence: AI + Internet of Things to realize automated, information-based, and flexible production, improving efficiency and yield.
2. Greenization: Environmentally friendly materials, energy conservation and emission reduction, low-carbon manufacturing, in line with the dual carbon goals.
3. Personalization: Customize voltage, capacity, structure, and interface according to scenarios/customer needs to improve adaptability.
4. Safety: Strengthen thermal runaway protection, multi-level safety interlock, and full-process risk control to ensure safe use.

1. Combination Method: For example, "1P24S" = 1 parallel and 24 series; S = series, P = parallel; rated voltage = single cell voltage × number of series (3.2V × 24 = 76.8V).

2. Rated Capacity: Unit is Ah, representing the continuous discharge capacity under standard working conditions; example: 280Ah ≈ 0.5C discharge can last for 2 hours.

3. Rated Energy: Unit is Wh/kWh, calculation formula: Rated Energy = Rated Voltage × Rated Capacity; example: 76.8V × 280Ah = 21504Wh = 21.504kWh.

Trumony aluminum limited is a leading global supplier specializing in high-performance liquid cooling solutions for energy storage and new energy applications. With over a decade of expertise in thermal management systems, we design and manufacture custom liquid cold plates, cooling manifolds, and integrated thermal solutions that are critical to the safety, efficiency, and longevity of battery PACK systems.

Our core offerings include high-precision aluminum liquid cold plates, engineered to meet the most demanding requirements of energy storage, EV, and industrial battery systems. We support clients worldwide with end-to-end services: from initial thermal simulation and design optimization, through CNC machining, friction stir welding, and laser welding, to full performance and leak testing.

If you are looking for high-quality liquid cold plates or custom thermal solutions for your battery PACK projects, please feel free to reach out to us anytime.

Sherry