As the core component of an energy storage system, the performance, safety, and reliability of an energy storage PACK directly affect the overall operational effectiveness of the system. With the rapid development of the new energy industry, the demand for energy storage PACKs is increasing, and the industry has put forward higher requirements for the design and manufacturing of PACKs. In order to ensure high-quality design and manufacturing of energy storage PACKs, the industry has developed a series of universal standards covering multiple aspects such as electrical, structural, and testing. This article will provide a detailed analysis of these standards and, combined with practical cases, help you fully understand the design and manufacturing points of energy storage PACKs.
1 Electrical standards: Ensure efficiency and safety
Electrical design is the core of energy storage PACK, directly related to the energy conversion efficiency and safety of the system. The following are key standards in electrical design:
1. Installation specifications for wire harness terminals
Installation with exposed copper wire facing upwards: The exposed copper wire of the wire harness terminal should be installed facing upwards to prevent dust, moisture and other pollutants from entering the contact surface, ensuring the reliability of the electrical connection. If the exposed copper wire is facing downwards, pollutants are prone to accumulate, leading to poor contact and even causing short circuits-
Terminal crimping requirements: The crimping between the terminal and the wire must be firm, with no cracks or looseness at the crimping point. Poor crimping can lead to an increase in contact resistance, causing local overheating, and in severe cases, may cause a fire. After crimping, a tensile test is required to ensure that the crimping strength meets the standard.
2. Installation method of spring pad and flat pad
Combination use of spring pad and flat pad: The spring pad is used to prevent bolt loosening, while the flat pad is used to distribute pressure and protect the connection surface. The installation sequence is: bolt → spring washer → flat washer → connecting piece
Torque requirement: The tightening torque of bolts must comply with the design specifications. Tightness may cause deformation of the connecting components, while looseness may lead to looseness, affecting the stability of electrical connections. Use a torque wrench for installation to ensure accurate torque values.
3. Electrical safety protection
Insulation resistance test: The insulation resistance of the energy storage PACK needs to reach the specified value (usually ≥ 100M Ω) to ensure electrical safety. Low insulation resistance may cause leakage or short circuit, leading to safety accidents.
Short circuit protection: PACK should be equipped with a short circuit protection device to prevent fires or explosions caused by short circuits. Common short-circuit protection measures include fuses, circuit breakers, etc.
2 Structural standard: Stable and durable
Structural design is the physical foundation of energy storage PACK, directly related to the mechanical strength and durability of the system. The following are key standards in structural design:
1. Box design
Mechanical strength: The box body needs to have sufficient mechanical strength to withstand external forces such as vibration, impact, etc. during transportation, installation, and operation. The box material is usually made of high-strength aluminum alloy or steel, and its strength is verified by finite element analysis (FEA).
Protection level: The protection level of the enclosure usually needs to reach IP54 or higher to prevent dust and water from entering. IP54 indicates that the box can prevent solid foreign objects with a diameter greater than 1mm from entering and can withstand water spray in any direction.
2. Thermal management system
Air cooling and liquid cooling design: Air cooling systems dissipate heat through fans and cooling fins, while liquid cooling systems manage heat through cold plates or submerged coolant. The temperature difference of the system needs to be controlled within ≤ 5 ℃ to extend the battery life. Excessive temperature difference can lead to uneven lifespan of battery modules and affect overall performance.
Temperature monitoring: PACK needs to be equipped with a temperature sensor to monitor the battery temperature in real time and prevent safety accidents caused by overheating. Common temperature sensors include NTC thermistors and thermocouples.
3. Module fixation
Bolt connection: High strength bolts should be used to fix the battery module to the box, and tightened according to the specified torque to ensure that the module does not loosen in a vibrating environment.
Seismic design: Add shock-absorbing pads between the module and the box to reduce the impact of mechanical vibration on the battery. Shockproof pad materials are usually made of silicone or rubber, which have good elasticity and durability.
3 Test standard: Verify performance and reliability
Testing is a crucial step in verifying the performance and safety of energy storage PACKs. The following are the key criteria in the testing:
1. Performance testing
Energy density and power density testing: Evaluate the energy density and power density of the PACK through charge and discharge testing to ensure that it meets design requirements. The higher the energy density, the stronger the energy storage capacity of the PACK; The higher the power density, the stronger the discharge capability of the PACK.
Cycle life testing: Simulate actual usage conditions, test the number of charge and discharge cycles of the PACK, and evaluate its service life. It is usually required that the cycle life of PACK reach 5000 times or more.
2. Security testing
Overcharge/Overdischarge Protection Test: Test the protection function of the PACK under overcharge or overdischarge conditions to ensure that it can timely cut off the circuit and prevent battery damage.
Voltage withstand test: Conduct a high-voltage test on the PACK to verify whether its insulation performance meets the standards. The withstand voltage test usually requires the PACK to maintain a non breakdown state for 1 minute at 1.5 times the rated voltage.
3. Environmental adaptability testing
High and low temperature testing: Place the PACK in high temperature (such as 60 ℃) and low temperature (such as -20 ℃) environments to test its performance stability. High and low temperature testing can verify the reliability of PACK in extreme environments.
Salt spray test: Simulate coastal or industrial environments to test the corrosion resistance of PACK. Salt spray testing typically requires PACK to be exposed to a salt spray environment for at least 48 hours without significant corrosion.