Lithium Battery Testing Standards in China and Abroad
In recent years, China has made significant progress in the formulation and application of standards for power lithium-ion batteries. However, there is still a certain gap compared to foreign standards. In addition to testing standards, China’s standards system for lithium-ion batteries is gradually being improved in other aspects.
On November 9, 2016, the Chinese Ministry of Industry and Information Technology (MIIT) released the ‘Comprehensive Standardization Technical System for Lithium-ion Batteries.’ It pointed out that the future standard system will include five major parts: basic general standards, materials and components, design and manufacturing processes, manufacturing and testing equipment, and battery products.
Among these, safety standards play a significant role. As power battery products evolve and develop, testing standards also need to improve corresponding detection technologies to enhance the safety level of power batteries.
01 Foreign Standards for Power Lithium-ion Batteries
(1) International Standards
– The International Electrotechnical Commission (IEC) has published several standards for power lithium-ion batteries, including:
- IEC 62660-1:2010 ‘Lithium-ion traction battery packs for electric road vehicles – Part 1: Performance testing’
- IEC 62660-2:2010 ‘Lithium-ion traction battery packs for electric road vehicles – Part 2: Reliability and abuse testing.’
– The United Nations Economic Commission for Europe (UNECE) has issued UN 38.3, ‘Recommendations on the Transport of Dangerous Goods – Manual of Tests and Criteria.’ It outlines requirements for testing lithium batteries concerning their safety during transportation.
– ISO has developed standards for power lithium-ion batteries, including:
- ISO 12405-1:2011 ‘Electrically propelled road vehicles – Test specification for lithium-ion traction battery packs and systems – Part 1: High-power applications.’
- ISO 12405-2:2012 ‘Electrically propelled road vehicles – Test specification for lithium-ion traction battery packs and systems – Part 2: High-energy applications.’
- ISO 12405-3:2014 ‘Electrically propelled road vehicles – Test specification for lithium-ion traction battery packs and systems – Part 3: Safety requirements.’
These standards address high-power batteries, high-energy batteries, and safety requirements, aiming to provide vehicle manufacturers with a range of test items and test methods to choose from.
(2) American Standards
– UL 2580:2011 ‘Batteries for Use in Electric Vehicles’ primarily assesses the battery’s resistance to abuse and its ability to protect individuals when abuse leads to harm. This standard was revised in 2013.
– SAE, having a comprehensive standard system in the automotive field, issued several standards:
- SAE J2464:2009 ‘Electric and Hybrid Vehicle Rechargeable Energy Storage System (RESS) Safety and Abuse Testing’ is an early guide for automotive battery abuse tests, applied in North America and globally. It specifies the scope of each test item and the required data to collect, as well as provides recommendations for the number of samples needed.
- SAE J2929:2011 ‘Electric and Hybrid Vehicle Battery Systems Safety Standard’ is an SAE safety standard that summarizes various previously issued power battery standards. It includes two parts: routine scenario tests during electric vehicle operation and tests for abnormal scenarios.
- SAE J2380:2013 ‘Vibration Testing of Electric Vehicle Batteries’ is a classic standard for vibration testing of electric vehicle batteries. It uses data collected based on the vibration load spectrum during actual road driving, making the test method more aligned with real-world vehicle vibration conditions and offering valuable reference value.
(3) Standards from Other Organizations
– The U.S. Department of Energy (DOE) is primarily responsible for energy policy development, energy industry management, and energy-related technology research and development.
In 2002, the U.S. government initiated the ‘Freedom CAR’ project, which subsequently issued the ‘Freedom CAR Power Assist Hybrid Electric Vehicle Battery Test Manual’ and the ‘Abuse Testing of Energy Storage System for Electric and Hybrid Electric Vehicles’ manual.
– The German Association of the Automotive Industry (VDA) is an association established to unify various standards for the domestic automotive industry in Germany.
The VDA 2007 standard, ‘Testing of Battery Systems for Hybrid Electric Vehicles,’ primarily focuses on the performance and reliability testing of lithium-ion battery systems for hybrid electric vehicles.
– The Economic Commission for Europe (ECE) Regulation R100.2, titled ‘Uniform Provisions Concerning the Approval of Vehicles with Regard to Specific Requirements for Electric Vehicles,’ is a set of specific requirements set by the ECE for electric vehicles. It is divided into two parts:
- The first part provides regulations for the whole vehicle in terms of motor protection, rechargeable energy storage systems, functional safety, and hydrogen emissions.
- The second part introduces specific requirements for the safety and reliability of rechargeable energy storage systems.
02 Chinese Domestic Standards for Lithium-ion Power Batteries
-In 2001, the Automobile Standardization Committee issued the first guiding technical document for testing lithium-ion batteries for electric vehicles in China, GB/Z 18333.1:2011 ‘Lithium-ion Battery for Electric Road Vehicles.’
This standard was developed with reference to IEC 61960-2:2000 ‘Portable Lithium-ion Cells and Batteries – Part 2: Lithium-ion Batteries,’ which is intended for lithium-ion batteries and battery packs used in portable devices. The testing covers both performance and safety but is only applicable to batteries with voltages of 21.6V and 14.4V.
– In 2006, the Ministry of Industry and Information Technology issued QC/T 743 ‘Lithium-ion Power Battery for Electric Vehicles,’ which has been widely used in the industry and was revised in 2012.
Both GB/Z 18333.1:2001 and QC/T 743:2006 are standards applicable at the individual and module levels.
However, their scope is relatively limited, and the testing criteria are no longer in line with the evolving needs of the rapidly growing electric vehicle industry.
– In 2015, the National Standardization Management Committee issued a series of standards:
- GB/T 31484-2015 ‘Requirements and Test Methods for Cycle Life of Power Batteries for Electric Vehicles.’
- GB/T 31485-2015 ‘Safety Requirements and Test Methods for Power Batteries for Electric Vehicles.’
- GB/T 31486-2015 ‘Electrical Performance Requirements and Test Methods for Power Batteries for Electric Vehicles.’
- GB/T 31467.1-2015 ‘Test Procedures for High-Power Applications of Lithium-ion Power Battery Packs and Systems for Electric Vehicles.’
- GB/T 31467.2-2015 ‘Test Procedures for High-Energy Applications of Lithium-ion Power Battery Packs and Systems for Electric Vehicles.’
- GB/T 31467.3 ‘Test Procedures for Safety Requirements and Test Methods of Lithium-ion Power Battery Systems for Electric Vehicles.
GB/T 31485-2015 and GB/T 31486-2015 are specific standards for the safety and electrical performance testing of individual modules.
The GB/T 31467-2015 series is based on the ISO 12405 series and is applicable to testing battery packs or battery systems.
While GB/T 31484-2015 is a dedicated standard for cycle life testing, where standard cycle life is applied to individual modules, and operational cycle life is used for battery packs and systems.
– In 2016, the Ministry of Industry and Information Technology (MIIT) released the ‘Safety Technical Specifications for Electric Buses.’ These specifications comprehensively address aspects such as electric shock protection, water and dust protection, fire protection, charging safety, collision safety, remote monitoring, and more.
They draw upon existing traditional bus and electric vehicle standards, as well as local standards in places like Shanghai and Beijing. The specifications impose higher technical requirements for power batteries and introduce two new testing items: thermal runaway and thermal runaway propagation. They were officially implemented on January 1, 2017.
03 Analysis of Domestic and International Standards for Power Lithium-Ion Batteries
Most international standards were published around 2010, with frequent revisions and the introduction of new standards over time. GB/Z 18333.1: 2001 was issued in 2001, indicating that China’s lithium-ion battery standards for electric vehicles didn’t start later than in the rest of the world. However, their development has been relatively slow.
After the release of the QC/T 743 standard in 2006, China went through a long period without any standard updates. Additionally, there were no standards for battery packs or systems until the new national standards were introduced in 2015.
The Chinese and international standards mentioned above differ in terms of their scope of application, the content of test items, the rigor of testing procedures, and the criteria for evaluation.
Scope of Application
The IEC 62660 series, QC/T 743, GB/T 31486, and GB/T 31485 are designed for testing at the individual cell and module levels. While UL2580, SAE J2929, ISO12405, and GB/T 31467 series are applicable to battery pack and battery system testing.
With the exception of IEC 62660, most foreign standards primarily involve testing at the battery pack or system level, and SAE J2929 and ECE R100.2 even mention vehicle-level testing.
This indicates that foreign standards take more consideration of the battery’s application within the whole vehicle, making them better aligned with real-world requirements.
Test Categories
All test categories can be broadly divided into two main categories: electrical performance and safety reliability.
Safety reliability can be further categorized into mechanical reliability, environmental reliability, abuse reliability, and electrical reliability.
- Mechanical Reliability
It simulates the mechanical stresses experienced by the vehicle during operation, such as vibrations that replicate the vehicle’s movement on the road.
- Environmental Reliability
It simulates the vehicle’s resistance to different climates, such as temperature cycling that represents the vehicle’s performance in areas with significant day-night temperature variations or during travel in both cold and hot regions.
- Abuse Reliability
This category tests how the battery performs in cases of improper use, such as fire testing, to evaluate the battery’s safety under adverse conditions. Electrical reliability includes protective tests, primarily examining whether the Battery Management System (BMS) functions effectively during critical situations.
- Battery Cell-Level Testing
In this aspect, IEC 62660 is divided into two independent standards, IEC 62660-1 and IEC 62660-2, which correspond to performance and reliability testing.
GB/T 31485 and GB/T 31486 evolved from QC/T 743, and GB/T 31486 categorizes vibration resistance as a performance test since this test assesses the impact of vibration on battery performance.
Compared to IEC 62660-2, GB/T 31485 has more stringent test items, such as adding needle penetration and saltwater immersion.
- Regarding Battery Pack and System Testing
In both electrical performance and reliability, American standards cover the most testing items. In terms of performance testing, DOE/ID-11069 includes additional test items compared to other standards, such as Hybrid Pulse Power Characterization (HPPC), operating set point stability, calendar life, reference performance, impedance spectroscopy, module control inspection tests, thermal management loads, and system-level testing combined with life verification.
The standards’ appendices provide detailed analysis methods for electrical performance test results. Among them, HPPC testing can be used to assess the peak power of the traction battery, and the derived direct current internal resistance (DCIR) testing method has been widely used for battery internal resistance characteristic research.
- Reliability Aspects
– UL 2580 includes additional test items compared to other standards, such as unbalanced battery pack charging, withstand voltage, insulation, continuity testing, and cooling/heating stability system failure tests.
It also includes basic safety testing for battery pack components on the production line and strengthens safety review requirements for BMS, cooling systems, and protection circuit design.
– SAE J2929 requires fault analysis of various parts of the battery system and the preservation of related documentation, including improvement measures for easily identifiable faults.
– The ISO 12405 series standards encompass both battery performance and safety aspects. ISO 12405-1 is the battery performance test standard for high-power applications, while ISO 12405-2 is the battery performance test standard for high-energy applications. The former includes cold start and hot start as additional contents.
– The GB/T 31467 series combines the current state of development of power batteries in China and is modified based on the content of the ISO 12405 series standards.
What sets it apart from other standards is that both SAE J 2929 and ECE R100. 2 involve requirements for high-voltage protection, falling within the realm of electric vehicle safety.
The relevant testing items in China are outlined in GB/T 18384, with GB/T 31467. 3 stipulating that battery packs and battery systems must meet the requirements of GB/T 18384. 1 and GB/T 18384. 3 before undergoing safety testing.
Stringency
For the same test items, different standards specify different testing methods and criteria for judgment. For example, regarding the state of charge (SOC) of test samples:
- GB/T 31467. 3 requires the samples to be fully charged.
- ISO 12405 requires a SOC of 50% for power-type batteries.
- For energy-type batteries, a SOC of 100% is required.
- ECE R100. 2 mandates that the SOC of the battery should be above 50%.
- 3 has varying requirements for different test items, and some tests may require cycled batteries.
Furthermore, it requires that highly simulated tests, thermal tests, vibration, impact, and external short-circuit tests must be conducted using the same sample, which is relatively stricter. For vibration testing, ISO 12405 requires samples to be vibrated at different environmental temperatures, with recommended high and low temperatures of 75°C and -40°C, a requirement not found in other standards.
Regarding the burn test, the experimental methods and parameters in GB/T 31467. 3 are quite similar to ISO 12405. 3, where both involve preheating, direct flame ignition, and indirect flame ignition. However, GB/T 31467. 3 stipulates that if a flame is present, it must be extinguished within 2 minutes, while ISO 12405 does not specify a flame extinction time.
SAE J2929 differs in its burn test from the previous two. It requires the sample to be placed in a radiant heat container, rapidly heated to 890°C within 90 seconds, and maintained for 10 minutes, with no components or materials allowed to pass through the metal mesh screen placed outside the test sample.
Shortcomings of Existing China Domestic Standards
Although the development and publication of relevant national standards have filled the gap in China’s lithium-ion battery pack systems and are widely adopted, there are still shortcomings.
- Testing Object
All standards only specify testing for new batteries, with no regulations or requirements for used batteries.
Just because a battery is trouble-free when it leaves the factory doesn’t mean it remains safe after some period of use.
Therefore, it is necessary to subject batteries used for different periods to the same tests, similar to regular check-ups.
- Result Assessment
Current criteria for assessment are broad and single, only specifying no leakage, no casing rupture, no ignition, and no explosion. A quantifiable evaluation system is lacking. The European Council for Automotive R&D (EUCAR) classifies the severity of battery hazards into eight levels, providing valuable insights.
- Regarding Testing Aspects
GB/T 31467.3 lacks testing content for thermal management and thermal runaway of battery packs and battery systems, while thermal safety performance is crucial for batteries. Controlling thermal runaway in individual cells and preventing its spread is of significant importance.
The mandatory implementation of the ‘Safety Technical Conditions for Electric Buses’ also underscores this point.
Furthermore, from the perspective of whole-vehicle applications, it is necessary to add electrical performance testing after non-destructive reliability testing, such as environmental reliability, to simulate the impact on performance after the vehicle experiences environmental changes.
- Regarding Testing Methods
The cycle life testing for battery packs and battery systems is time-consuming, affecting product development cycles, and it is difficult to execute well. Developing a reasonable accelerated cycle life testing method is a challenging task.