Reliability Test for Battery

With the continuous expansion and widespread use of batteries, the safety of batteries is becoming more and more important. After they are produced, battery manufacturers must conduct strict safety tests on them to ensure the safety of batteries and reduce potential safety hazards and accidents. But what exactly are them? LIB INDUSTRY will introduce the durability tests and related test standards for batteries.

Why do Batteries Need Reliability Test Before Leaving the Factory?

Batteries have been widely used in notebook computers, medical equipment, aerospace, communication mobile phones, electric hand tools, children's electric toys and other electronic products, and the power source for electric vehicles and hybrid vehicles is the key in the future. Therefore, safety has become an important issue in the development of batteries. Since the notebook computer lithium batteries made by SONY were recalled in large quantities due to explosions in 2006, there have been explosions in mobile phones and Apple iPhones. Therefore, in order to avoid such security incidents, battery testing has become a necessary item.

We consider this problem from 3 dimensions

1.The first dimension is battery companies. As an OEM (original equipment manufacturer) of power batteries, battery companies must pass a series of tests to obtain battery characteristics. In order to facilitate understanding, you can compare this type of test to: People often use IQ tests, personality tests, physical fitness tests and other evaluation items to understand their own characteristics and strengths, so as to make better decisions for personal development. Battery companies need to fully grasp the characteristics of their batteries, so as to provide the necessary decision-making basis for battery management algorithms.

2.The second dimension is vehicle manufacturers. As users of power batteries, vehicle manufacturers need to evaluate and test whether the selected batteries meet the performance requirements of the product's full life cycle.

3. The third dimension is the certification institutions. As market regulators, certification institutions need to use standards and regulations to eliminate some unsafe, unenvironmental, and uneconomical outdated products, and identify them through effective testing methods to prevent them from entering the market.

What are the Standards for Battery Reliability Test?

Commonly used foreign battery test standards:

Standard issuing institutions mainly include the International Electrotechnical Commission (IEC), the International Organization for Standardization (ISO), the Underwriters Laboratories (UL), the Society of Automotive Engineers (SAE) and relevant European Union agencies.

1 International standards

The power battery standards released by IEC mainly include IEC 62660-1:2010 and IEC 62660-2:2010

The standards formulated by ISO in terms of power batteries include ISO 12405-1: 2011 , ISO 12405-2: 2012 and ISO 12405-3:2014 aiming at high-power batteries, high-energy batteries and safety performance requirements, the purpose is to provide optional test items and test methods for OEMs.

2 American Standards

UL 2580: 2011 "Battery for Electric Vehicles" mainly evaluates the reliability of battery abuse and the ability to protect people when abuse causes harm. This standard was revised in 2013.

SAE has a large and complete standard system in the automotive field. SAE J2464: 2009 "Safety and Abuse Tests for Rechargeable Energy Storage Systems for Electric and Hybrid Electric Vehicles" promulgated in 2009 is an early batch of vehicle battery abuse test manuals used in North America and the world, clearly stating that the scope of application of each test item and the data to be collected also give suggestions on the number of samples required for the test item.

SAE J2929: 2011 "Safety Standards for Electric and Hybrid Battery Systems" promulgated in 2011 is a safety standard proposed by SAE on the basis of various power battery-related standards promulgated before, including two parts: Electric vehicles may appear during driving normal case test and abnormal case test.

SAE J2380: 2013 "Vibration Test of Electric Vehicle Batteries" is a more classic standard for vibration testing of electric vehicle batteries. Based on the statistical results of vibration load spectrum collection of actual vehicle road driving, the test method is more in line with the actual vehicle vibration conditions. It has important reference value.

3 Other organizational standards

The U.S. Department of Energy (DOE) is mainly responsible for energy policy formulation, energy industry management, and energy-related technology research and development. In 2002, the U.S. government established the "Freedom CAR" project, and successively issued the Freedom CAR power-assisted hybrid electric vehicle battery test manual and the abuse test manual for energy storage systems for electric and hybrid vehicles.

The German Automobile Industry Association (VDA) is an association formed by Germany to unify various standards of the domestic automobile industry. The standards promulgated include VDA 2007 "Battery System Test for Hybrid Vehicles", which is mainly aimed at battery systems for hybrid vehicles. performance and reliability testing.

Economic Commission for Europe (ECE) R100.2 "Unified Regulations on the Approval of Vehicles with Special Requirements for Electric Vehicles" is a specific requirement formulated by ECE for electric vehicles. The four aspects of rechargeable energy storage system, functional safety and hydrogen emission have been regulated. The second part is the newly added specific requirements for the safety and reliability of rechargeable energy storage system.

What Reliability Tests do Batteries Need to do?

1.Temperature shock and cycle test

This test primarily evaluates changes in battery integrity due to exposure to extreme and sudden temperature changes, such as expansion and contraction of battery components when a vehicle enters or exits a heated or refrigerated garage during transport. During temperature shock and cycling tests, the battery is subjected to two temperature limits, high and low, and held at each temperature limit for a specified time. The temperature shock and cycle tests described in standards and regulations have different maximum temperature limits. The lower temperature limit of all standards and regulations is -40°C (IEC62660-2 has a minimum temperature of -20°C in the case of live operation), although the upper temperature limit is different.

2.Thermal Stability Test

This test mainly evaluates the stability of the battery at high temperature to identify the battery thermal runaway start temperature or the stability at high temperature. During the test, the temperature of the battery is sequentially increased at a step of 5°C/min, raised to the specified temperature and maintained for 30 minutes, or until major damage to the battery occurs.

The standard SAEJ2464:2009 is more stringent, not only requiring a heating rate of 5°C/min, but also maintaining a temperature of 30 minutes at each temperature step, and requiring a maximum temperature of 300°C (higher than the maximum operating temperature of the battery) until the temperature reaches 300°C or Self-heating occurs (greater than 1.0°C/min). It is used to evaluate the thermal runaway start time and thermal stability of the battery.

Other standards evaluate the performance of the battery at high temperatures, and the goal is not to reach a thermal runaway condition, but to evaluate the thermal stability of the battery at that temperature. The battery is sequentially increased from room temperature at a step of 5°C/min to 130°C, and placed at this temperature for 30 minutes.

3.aging test

The performance of batteries after high-temperature aging is more stable. Most battery manufacturers adopt high-temperature aging operation methods in the production process. The temperature is 45-50 degrees Celsius for 1-3 days, and then shelved at room temperature.

Potential adverse phenomena of batteries will be exposed after high-temperature aging: such as voltage changes, thickness changes, and internal resistance changes are all direct tests of the comprehensive indicators of safety and electrochemical performance of these batteries.

Battery Reliability Test Methods and Cases

Short circuit test:

1) At 25°C, put a single battery in the environmental test chamber and let it stand for 30 minutes to ensure that the overall temperature of the single battery is consistent with the temperature in the environmental test chamber;

2) Perform short-circuit excitation to the single battery in step 1), the short-circuit resistance is10min;

3) Record the voltage, short-circuit current and temperature changes of the short-circuit battery, and test the state and weight of the single battery before and after the experiment.

Overcharge test:

1) At 25°C, put a single battery in the environmental test chamber and let it stand for 30 minutes to ensure that the overall temperature of the single battery is consistent with the temperature in the environmental test chamber;

2) Excite the single battery in step 1) by overcharging, the overcharging current is 1C, and the overcharging time is 90 minutes;

3) Record the voltage and temperature changes of the overcharged battery, and the state and weight of the single battery before and after the test.

Heating test:

1) At 25°C, put a single battery in the environmental test chamber and let it stand for 30 minutes to ensure that the overall temperature of the single battery is consistent with the temperature in the environmental chamber;

2) Heating the single battery in step 1), the heating temperature is 130°C, and the heating time is 60 minutes;

3) Record the voltage and temperature changes of the heating battery, and test the state and weight of the single battery before and after the experiment.

The needed equipment:temperature and humidity test chamber, Thermal shock test chamber, Drying oven.

Requirements: Test for no leakage, no venting, no open circuit, no rupture, no explosion and no fire.

Thermal cycling Purpose: This test evaluates the sealing integrity of cells and batteries and their internal electrical connections, and tests the temperature of use cycle test.

Test procedure: Store cells or batteries at a temperature of 72°C for at least 6 hours, then store them at -40°C for at least 6 hours, and the switching time between the two temperatures should not exceed 30 minutes. Each cell or battery should be tested for 10 hours. Cycle, and then stored at room temperature for 24 h. For large batteries and cells, the storage time at the test temperature should not be less than 12h.

Requirements: No leakage, no exhaust, no open circuit, no rupture, no explosion and no fire during the test IEC 62660-2 Reliability and Abuse Test of Lithium Batteries for Electric Vehicles High Temperature Endurance: Batteries are heated in a natural convection or forced convection oven , the temperature of the oven is raised to 130°C at a speed of 5±2/min, and the battery is operated at this temperature for 30 minutes.

Temperature Cycling. This test is designed to characterize the thermal durability of a battery by alternating exposure to low and high temperature environments to induce expansion and contraction

Put the battery into the test chamber for 5 cycles, and observe for 1 hour after the end. The U11642 lithium battery standard heating test sample is heated in a natural convection or forced convection oven. The temperature of the oven is raised to 130°C at a rate of 5±2°C/min and maintained for 10 minutes.

Summary and Our Service

Batteries have become an essential part of everyday life. Batteries are widely used in various industries, so battery pack, battery module and cell testing is critical to user safety. With the popularization of electric vehicles, the demand for the safety of electric vehicle batteries will also increase. Performing full life cycle and capacity testing is a critical step in verifying battery safety and durability.

When you choose LIB INDUSTRY, you will work with our professional team with comprehensive knowledge in battery performance testing and other advantages:

● Our experts lead the way in battery testing and continue to support you along the entire value chain from component to final product, keeping you ahead of the competition.

● During the R&D process, our testing services will support you in making technical decisions that best serve your design goals, while also having a long-term impact on battery performance.

● Our equipment opens up the possibility of quality improvement and reduces the risk of recalls and warranty claims after the product has been placed on the market.

● Our testing solutions are effective, reducing your product development time and getting products to market faster.

● Ensure the performance of your batteries with our battery reliability testing services, and our tests can make the difference between your commercial and practical success.