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Power Lithium‑Ion Battery Pack Factory Testing: The Quality Code Behind Rigorous, Multi‑Layered Inspections
time：2026-07-23
A power lithium battery PACK goes offline from production line to vehicle loading, and there are strict test levels in the middle. These tests are not only the bottom line requirements for regulatory compliance, but also the lifeline of enterprise quality reputation. This article will uncover the five core test links that battery pack must go through before leaving the factory, and see how a qualified battery pack "passes the pass".
I. Electrical performance test: accurate measurement of energy boundary
electrical performance is the basic skill of battery pack, and a full-dimensional physical examination must be conducted before leaving the factory ".
Capacity and energy testing it is the primary project. At the standard temperature (25℃ ± 2℃), battery pack needs to undergo a complete charge and discharge cycle, and the measured capacity shall not be less than 95% of the nominal value. This test directly determines whether the mileage that users are most concerned about is "genuine".
DC internal resistance (DCR) test the same key. The internal resistance of battery pack under different SOC States is measured by high current pulse method, and its power output capability and heating characteristics are evaluated. Abnormal internal resistance often indicates poor linking or cell aging, which is an early signal of potential failure.
self-discharge rate test the standby capability of battery pack is tested. Leave the full power battery pack for 28 days, and the capacity attenuation must be controlled within 5%. Excessive self-discharge means that there is a slight short circuit or leakage risk, which must be intercepted before leaving the factory.
II. Safety performance test: hold the last line of defense before the cinema line
the safety test is the "red line" of the factory battery pack. If any item is not up to standard, the whole batch of products cannot be released.
Overcharge/overdischarge test simulate extreme abuse scenarios. Charge the battery pack to 120% of the rated voltage or discharge it to 0V, and observe whether there are drum bag, leakage, fire and other abnormalities. Although BMS theoretically cuts off the circuit, the test verifies the hardware redundancy protection capability.
Short circuit test there are two types: internal short circuit and external short circuit. The external short circuit test requires that battery pack do not catch fire or explode within 10 minutes after the positive and negative poles are shorted. The internal short circuit test is triggered by acupuncture or extrusion to verify the safety design of the electric the rate of pillow inner.
thermal runaway diffusion test it is a key project newly added by laws and regulations in recent years. The heat of a single cell is out of control by heating or acupuncture. It requires no fire or explosion within 5 minutes to gain valuable time for passengers to escape. This test directly promoted the upgrade of PACK structure design such as heat barrier material and pressure relief channel.
III. Environmental adaptability test: Crossing the test of four seasons and mountains and rivers
the power battery pack needs to work normally in Mohe at-30℃ and Turpan at 45℃, so environmental adaptability test is indispensable.
High and low temperature charge and discharge test cover the full temperature range from-20℃ to 55℃. At low temperature, the charging acceptance ability and discharge power retention rate are mainly examined, while at high temperature, the capacity attenuation and thermal management efficiency are concerned. Generally, the discharge capacity at-20℃ is not less than 70% of the nominal value.
Temperature cycle and damp heat test simulate long-term climate erosion. Battery pack need to be circulated between-40℃ to 85℃ for dozens of times, and stand in a high humidity environment of 85℃/85% RH for 48 hours to verify the sealing performance and weather resistance of the material. Any lotion entering the box may lead to insulation failure or corrosion.
mechanical vibration and impact test reproduce the driving conditions of the whole vehicle. Battery pack need to experience random vibration and semi-sinusoidal impact for several hours on the vibrating table to simulate the mechanical load of potholes and emergency braking. After the test, it needs to be disassembled and checked to confirm that there is no displacement in cell, no cracking in solder joints, and no deformation in structure.
4. BMS function verification: software-defined security precision battle
the battery management system (BMS) is battery pack "brain", and its function verification runs through the whole factory test process.
SOC estimation accuracy verification it is required that the SOC display error of BMS should not exceed 5% under different temperatures, different ratios and different aging states. This is directly related to the user's endurance anxiety and experience.
Balance function test verify the governance capability of BMS for cell inconsistency. Verify whether passive equilibrium or active equilibrium can pull the differential pressure back to the safety range within the specified time by artificially manufacturing a differential pressure of more than 20mV between cell.
Fault DiagnosisAnd protection testing then, simulate various abnormal working conditions-temperature sensor open circuit, CAN communication interruption, relay adhesion, etc., verify whether the BMS CAN internal trigger the protection action in milliseconds, and accurately report the fault code.
V. Air tightness and insulation test: invisible sealing and insulation, visible safety
air tightness test it is a required question before leaving the factory battery pack ". Helium mass spectrometer leak detection or pressure drop method is adopted to fill battery pack with gas at a certain pressure to monitor the leakage rate. IP67 level requires soaking in a certain water depth for 30 minutes without water inflow, and air tightness test is the pre-guarantee of this indicator.
Insulation Resistance Test high pressure safety. Under 500V DC voltage, the insulation resistance of battery pack positive and negative poles to the box should be greater than 500 Ω/V. Any insulation failure may cause electric shock risk in rainy days or wading. The test should cover multiple nodes such as normal, hot and humid, and vibration to ensure the safety of the whole life cycle.
One power lithium battery PACK the way to leave the factory is a quality network woven by hundreds of tests and thousands of data points. From electrical performance to safety redundancy, from environmental adaptation to intelligent management, every link is the practice of the concept of "zero defect. Today, when the new energy automobile industry is maturing, the depth and breadth of testing capability, is becoming an important ruler of the core competitiveness of enterprises.
Contact us
Dongguan Juneng New Energy Technology Co., Ltd.
137 5142 6524（Miss Gao）
susiegao@power-ing.com
Xinghuiyuan High tech Industrial Park, Dalang Town, Dongguan City, Guangdong Province
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