Importance of EV Battery Testing

At the heart of many of these advancements lies the lithium-ion battery, a powerhouse of stored energy that has revolutionized virtually every sector.

Of course, innovation starts with rigorous testing to ensure safety, reliability, and performance. This is where lithium-ion battery testing methods come into play.

The Importance of Lithium-Ion Battery Testing

While lithium-ion batteries are beneficial, they are not without their challenges. Issues such as thermal runaway, capacity degradation, and safety risks can arise if batteries are not properly designed and tested. This is where comprehensive battery testing becomes essential.

Battery testing serves multiple purposes, including:

• Safety Assurance: Ensuring that batteries are safe to use and do not pose any risk of fire or explosion, especially in high-stress environments such as automotive and aerospace applications.
• Performance Optimization: Evaluating the performance of batteries at normal and extreme temperatures, to optimize their efficiency and longevity.
• Reliability Testing: Subjecting batteries to accelerated aging tests to simulate real-world usage scenarios and predict their lifespan and performance over time.
• Quality Control: Identifying any manufacturing defects or inconsistencies in battery production processes to maintain high standards of quality and reliability.

Battery testing is essential for determining the durability and safety of batteries before they end up in the vehicles, devices, and energy storage systems consumers depend on daily. Ultimately, battery testing ensures products perform as expected. But they are also used to conduct research, develop advanced technologies, and condition batteries so they’re prepared for optimal performance. Plus, every commercial industry must conduct some form of testing to make sure all products are safe for consumers and end users, as well.

Battery testing is particularly important for electric vehicles (EVs). Batteries comprise the most critical component of a vehicle's powertrain, storing and supplying energy to the electric motor. Thus, battery testing impacts the vehicle's range, acceleration, and overall performance. It’s also crucial for the driver's and passengers' safety, as well as that of other road users.

Then there’s the expansion of the EV market to include SUVs, trucks, buses, and more as well as an array of climates. Consider for a moment the diverse range of environments an EV can encounter in a single day, driving between the dry heat of a desert, saline coastal air, or over frigid cold mountain passes, all while bearing the weight of passengers and the shocks of uneven roads. Companies must account for this in addition to city or highway driving.

Battery testing for EVs involves evaluating the battery's performance under different driving conditions, such as extreme temperatures, humidity, and load. This testing helps identify potential issues impacting the battery's performance, including degradation, overheating, and failure to charge or discharge correctly.

Testing also assures the battery can withstand the harsh conditions—vibrations, shock, and mechanical stress to name three—that will occur during the vehicle's operation, reducing the risk of failure and improving the vehicle's overall safety.

Lastly, battery testing is pivotal in developing new and improved EV battery technology Researchers and scientists use various testing methods to evaluate the performance of different materials and designs to build more efficient, longer-lasting, and cost-effective batteries .

Types of Battery Testing

Several different types of battery testing methods are used to evaluate the performance, safety, and reliability of batteries. Here are some of the most common types labs use.

Performance Testing

Performance testing involves evaluating the battery's electrical performance under different conditions, such as temperature, load, and charge and discharge cycles, and helps to determine the battery's capacity, efficiency, and overall performance.

Performance testing also helps engineers identify potential issues that could impact batteries’ reliability and safety.

Performance testing can entail the following:

• Capacity testing assesses the battery's ability to store and deliver electrical energy (in amperes or watts), discharging the battery to a specific level and measuring the amount of energy it provides over a given time period.
• Efficiency testing identifies how effectively the battery converts stored energy into electrical energy, measuring the battery's output voltage and current and calculating its efficiency. It’s like an overall health exam for the battery.
• Cycling testing ascertains the battery's ability to charge and discharge repeatedly by subjecting it to a series of charge and discharge cycles under different conditions, such as temperature and load. This tells you how long a battery can be used over its lifetime.
• Temperature testing determines the battery's performance under various conditions by exposing it to different heat ranges and measuring its output voltage and current.
• Aging testing judges the battery's performance over time by subjecting it to a series of charge and discharge cycles over an extended period and measuring its capacity and efficiency.
• Cell formation testing is the process of conditioning new batteries to ensure they perform at their best before being put into service. During cell formation testing, batteries are subjected to a series of charge and discharge cycles to activate and stabilize the electrodes and electrolytes within the battery. This enables them to reach full capacity and provide consistent performance throughout their lifetime.

Durability Testing

By exposing a battery to harsh conditions, such as vibration, shock, and mechanical stress, durability testing further assesses the hardiness and reliability of a battery. This testing helps to identify potential weaknesses or design flaws that could cause the battery to fail or become a safety hazard.

While performance testing focuses on the battery's electrical performance under different conditions, durability testing typically includes the following:

• Mechanical stress testing subjects the battery to force, such as tremors or oscillation, to identify its ability to withstand physical burdens and maintain its performance.
• Environmental testing uses test chambers to evaluate the battery's performance and reliability under different environmental conditions, such as humidity and temperature, revealing potential issues that could impact the battery's performance in real-world conditions.
• Abuse testing determines the battery's ability to withstand abuse, such as impacts or punctures, identifying possible safety hazards and developing appropriate safety measures.
• Life cycle testing assesses the battery's durability over its entire life cycle, including charge and discharge cycles, storage, and transportation. It determines the battery's useful life and reveals problems that could impact its performance or safety over time.

How Durability Testing Differs From Safety Testing

Durability and safety testing are both important aspects of evaluating batteries, but they differ in their objectives. Durability testing primarily evaluates the battery's ability to withstand harsh conditions and maintain its performance and reliability over time.

Safety testing, on the other hand, centers around evaluating the battery's immunity from harm and identifying potential hazards or risks associated with its use.

This typically involves subjecting the battery to various tests to determine its resistance to abuse, overcharging, short circuits, and thermal runaway. Safety testing may also include assessing the battery's performance under different temperature and humidity conditions to reveal potential hazards.

Battery Testing Equipment

To achieve safe and effective battery testing, labs utilize several important technologies. Let’s consider each of them.

Battery testers measure a battery's voltage, current, and resistance under different conditions. They can also calculate the battery's capacity (overall health), performance, and charge/discharge cycles.

Battery cyclers charge and discharge batteries repeatedly to assess their performance under different conditions and measure cell response over time.

Battery analyzers examine the chemical composition of batteries and identify potential issues that could impact their performance, measuring the battery's impedance, ripple current, charge, and temperature.

Battery management systems (BMS) monitor and control the charging and discharging of batteries while providing real-time data on the battery's performance. They’ll alert users to potential issues as well.

Data loggers record and store data from battery tests, including voltage, amperage, current, and temperature, monitoring battery performance over time and identifying trends.

Environmental chambers are enclosed workspaces that simulate different environmental conditions, such as temperature and humidity, to evaluate battery performance under various conditions. This specialized piece of equipment typically features precise control of temperature and humidity, as well as safety features to limit damage to the equipment and lab. Test chambers are designed to meet the rigorous standards and requirements of the battery industry, including safety regulations and industry-specific testing protocols.

Battery testing fixtures are mechanical devices used to secure batteries during testing, preventing any movement that could cause damage or inaccuracies in test results. Properly designed battery fixtures can also reduce the risk of safety hazards, such as battery explosions or fires, by minimizing the potential for short circuits or other electrical issues.

Industries That Conduct Battery Testing

Battery testing is used in a wide range of commercial industries. You’ll find battery testing is conducted in most manufacturing-related sectors.Here are some of the most prominent applications for battery testing.

Automotive

Battery testing is crucial in the automotive industry, where batteries are used to power EVs. For instance, manufacturers are focused on extending the range EVs have on a single charge, alleviating some of the so-called “range anxiety” many consumers experience. Labs will employ high-density battery test chambers and fixtures to conduct research and development on EV batteries

As society restructures transportation toward more renewable energy in response to the climate crisis, battery technology will continue playing a vital role in bringing about a greener future.

Aerospace

The aerospace industry tests batteries used in spacecraft and satellites, verifying whether cells can withstand the extreme conditions of space and perform reliably over long periods.

For instance, NASA tests lithium-ion batteries for potential use in the International Space Station (ISS).

Electronics

Battery testing is essential for companies that manufacture electronic devices, such as smartphones, laptops, medical equipment, and tablets. Rigorous testing ensures batteries are safe, reliable, and long-lasting before products end up in the hands of consumers.

Energy Storage

Battery testing is critical in the energy storage industry. While EVs utilize energy storage, there are many other applications for energy storage beyond transportation. These include:

• Grid-scale energy storage stocks excess renewable energy, such as wind or solar power, for use during times of high demand or when renewable energy sources are unavailable. This helps to balance the grid and ensure a reliable supply of electricity.
• Residential and commercial energy storage are used in homes and businesses to store excess energy from renewable sources or to provide backup power during outages. These systems can help to reduce energy costs and improve the resilience of the electricity grid.
• Remote power systems offer energy where access to the electricity grid is limited or nonexistent. These systems can power off-grid homes, telecommunications towers, and other remote applications.

Technological advancements hinge upon innovations in battery testing technology. Although companies approach battery testing differently, this much is true: a well-designed battery test chamber enables safe, efficient testing.

Lithium batteries are integral to our daily lives, powering a wide range of devices and technologies. However, their optimal performance and safety hinge on consistent testing throughout their lifecycle.

First let us dive deeper into the testing standards being followed:

Lithium battery test standards

The International Electrotechnical Commission (IEC), the International Organization for Standardization (ISO), and other standard-setting organizations in different nations and regions typically create testing standards for lithium batteries. The following are typical lithium battery test criteria:

1. Capacity Test Criteria:

ISO 12405-1:2011: Lithium-ion batteries and battery packs - Methods for measuring battery capacity and efficiency.

IEC 61960:2011: Rechargeable lithium-ion batteries and battery packs - Capacity

measurement methods.

2. Internal Resistance Test Standards:

ISO 12405-2:2013: Lithium-ion batteries and battery packs – Methods for measuring battery capacity and efficiency.

IEC 62620:2011: Rechargeable lithium-ion batteries and battery packs – Method for measuring AC impedance.

3. Cycle Life Test Standards:

ISO 12405-3:2011: Lithium-ion batteries and battery packs - Methods for measuring battery capacity and efficiency.

IEC 62660-2:2010: Rechargeable lithium-ion batteries and battery packs.

4. Temperature Test Standards:

ISO 12405-4:2014: Lithium-ion batteries and battery packs - Methods for measuring battery capacity and efficiency - Part 4: Temperature tests

IEC 62660-3:2013: Rechargeable lithium-ion batteries and battery packs

5. Safety Test Standards:

IEC 62133:2017: Safety requirements for rechargeable lithium-ion batteries and battery packs

GB/T 31485-2015: Safety requirements and test methods for lithium-ion batteries and battery packs.

Standards for testing lithium batteries may differ between nations. As such, it is imperative that lithium battery testing be carried out in accordance with local standards and that all applicable laws and safety mandates be followed. Additionally, depending on their own requirements, research facilities and manufacturers may create unique test protocols and standards.

Now lets explore the vital importance of testing lithium batteries at various stages to ensure their durability, efficiency, and safety.

1. Initial Quality Assurance:

The manufacturing process is the starting point for initial quality assurance, which is crucial to remove any defects that could compromise the safety and performance of lithium batteries.

Stringent testing protocols are implemented to identify and rectify issues such as manufacturing defects, voltage imbalances, and impurities in the electrolyte.

2. Cell Characterization:

Since lithium-ion batteries are made up of individual cells, testing is essential to characterize each cell and ensure uniform performance.

Parameters like capacity, voltage, and internal resistance are measured to identify outliers or weak cells that could disrupt overall battery performance.

3. Cycle Life Testing:

Lithium-ion batteries degrade over time due to chemical reactions during charge and discharge cycles.

Cycle life testing involves repetitive charge and discharge cycles to assess the number of cycles a battery can endure before a significant loss in capacity occurs. This information aids in estimating the battery's lifespan and setting realistic expectations.

4. Performance Under Stress Conditions:

Real-world scenarios often expose lithium batteries to extreme conditions.

https://www.youtube.com/watch?v=WoQyeSMjWcU

Testing under stress conditions assesses battery resilience and safety margins, crucial for applications like electric vehicles operating in harsh environments and under demanding usage patterns.

5. Monitoring and Maintenance:

Continuous monitoring during the operational life of lithium batteries is crucial to detect anomalies or deviations from expected behavior.

Battery management systems (BMS) play a pivotal role in real-time monitoring and control. Regular testing and maintenance identify issues early, allowing preventive measures and extending the overall lifespan of the battery.

6. Safety Testing:

Safety concerns, including overheating and explosions, have been associated with lithium-ion batteries

Comprehensive safety testing, such as thermal abuse and crush testing, helps understand battery behavior under extreme conditions and design safety mechanisms to prevent catastrophic failures.

7. End-of-Life Recycling:

As lithium batteries reach the end of their operational life, proper disposal and recycling become crucial.

Testing at this stage involves assessing residual capacity and determining whether the battery can be repurposed for secondary applications or safely recycled. Recycling lithium batteries is not only environmentally responsible but also aids in recovering valuable materials for reuse.

Testing lithium batteries throughout their lifecycle is a critical and multifaceted process ensuring their longevity, performance, and safety.

From initial quality assurance to end-of-life recycling, comprehensive testing protocols contribute to the development of reliable and sustainable energy storage solutions. Ongoing research and innovation in battery testing methodologies will continue to play a pivotal role in addressing the evolving needs of industries reliant on lithium-ion batteries.