Do you know that energy storage system testing is a hot topic today? In so-called “battery testing”, they range from small portable batteries to large batteries used in electric vehicles (EVs) to backup batteries used in backup systems for high energy supplies.
Depending on the specific environment and manufacturing cycle stage of these systems, battery testing provides the market with test solutions such as those designed to meet the stringent needs of system integrators designing automated test systems (ATE) for electric vehicle OEMs. As technology advances, Linkotest continues to accumulate experience with various test cases and production quality requirements.
All your questions about battery testing are answered in today’s guide. Whether you want to know about types, features, or standards, you can find everything here. Read on to learn more.
（Another Related Article: Battery Safety Test 101: A Complete Guide）
1. The dilemma of battery testing
It is difficult to test batteries in storefronts, hospitals, battlefields, and service garages, which contributes to the problem. Rapid battery testing methods appear to have existed in the Middle Ages, which is especially evident when comparing other advances. We don’t even have a reliable way to estimate the state of charge, which is mostly based on voltage and coulomb counting. Assessing capacity, the primary health indicator of a battery is even further behind. Measuring open circuit voltage and checking internal resistance does not provide definitive evidence of battery health.
Battery users may ask, “Why is the industry so far behind?” It is true that there is no single analytical device that can assess a person’s health, but there is no instrument that can quickly and reliably assess battery health. Like the human body, batteries can harbor multiple hidden flaws, and no single test method can identify them with certainty.
Battery drain is easy to check and all testers are 100% accurate. The challenge is how to evaluate the battery in the operating range of 80% to 100% performance. Regulators struggle to introduce battery testing procedures. This is mainly due to the lack of suitable techniques that can evaluate batteries dynamically. The battery is marked “uncontrollable” for a good reason; this confers immunity on it.
The battery community has put a lot of effort into supercells, but no such improved battery is complete without being able to check performance while in use. Improving performance and reliability isn’t just about better batteries, it’s about tracking performance as batteries age.
2. What is Battery testing?
Battery testing is designed to tell us what we want to know about individual cells and battery packs. Here is some information that can be gleaned from battery testing.
1) Indirect measurement
Despite the fact that all battery parameters can be measured directly, this is not always convenient or possible. For example, the amount of charge remaining in a battery, the state of charge (SOC), can be determined by fully discharging the battery and measuring the energy output.
The process takes time, wastes energy, shortens battery life, and may not be practical if the battery is in use. This is also meaningless for primary cells. Likewise, the remaining life of a secondary battery can be determined by cycling it until it fails, as I have a friend who is a used iPhone wholesale supplier. He is using this method to determine the secondary battery life of second-hand mobile phones. But knowing its life expectancy is pointless if you have to destroy it to know the life expectancy of the battery.
This is called the battery’s state of health (SOH). As an approximation or indirect measure of the desired parameter, a simple test or measurement is needed.
2) Battery design process test
A more detailed testing regime is required in the design of new batteries.
3) Test conditions
In all of the following tests and tests in general, test conditions must be specified so that reproducible results can be obtained and meaningful comparisons can be made. Factors such as method, temperature, DOD, load, and duty cycle are considered.
For example, battery capacity and cycle life, two key performance indicators, can vary by 50 percent or more depending on the temperature and discharge rate at the time of testing. Battery specifications should always include test conditions to avoid ambiguity.
4) Qualification test
In order for a cell or battery pack to be approved for use in a product, it must undergo qualification testing. This is especially important if the battery is to be used in “mission-critical” applications. These are thorough tests initially performed on a small number of batteries, including testing some of them for destruction if necessary.
As a second stage, qualification also includes testing the finished battery pack before the product is approved for release to customers. Batteries are commonly tested to ensure that they meet the manufacturer’s specifications, but they can also be tested to arbitrary limits set by the application engineer to determine how long they will last under adverse conditions or under unusual loads.
To ensure compatibility, the battery pack should also be tested with the charger recommended for the application. To avoid inadvertent overcharging, potential user patterns must be evaluated.
5) Shake and Bake
- Mechanical testing
Typical tests are included in safety standards. The tests include simple dimensional accuracy tests and dynamic tests to ensure that a product can withstand static and dynamic mechanical stresses.
Typical tests are included in safety standards. They are designed to operate in all environmental conditions the product may encounter during its useful life.
6) Abuse testing
The purpose of abuse testing is to verify that the battery will not pose a danger to the user or the battery itself through accidental or deliberate misuse under any conceivable condition of use. Designing foolproof batteries is getting harder because fools are known to be so smart.
Abuse testing (always fun) is often specified as part of security testing. Recent lithium battery accidents have highlighted potential dangers, and stricter battery design rules, more extensive testing, and stricter shipping of products are being implemented
7) Safety standards
Consumer products usually must meet national or international safety standards required by safety organizations in the country where the product is sold. Examples include UL, ANSI, CSA, and IEC standards. Published safety standards specify the test methods and limits to which a product must comply.
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8) DEF standard
Batteries used in military applications typically must meet stricter requirements than batteries used in consumer products.
9) Loop test
This is perhaps the most important qualification test. Charge and discharge the battery to ensure that it meets or exceeds your stated cycle life. Generally, the cycle life of a battery is the number of charge-discharge cycles it can perform before its nominal capacity drops below 80% of its original capacity. Testing is required to ensure that battery performance meets the ultimate reliability and life expectancy of your product without compromising warranty coverage.
In order to obtain repeatable results that can be compared to standards, temperature, and DOD should be controlled at agreed reference levels. Alternatively, these tests can be used to simulate operating conditions that allow for increased temperatures or limit DOD to determine how cycle life will be affected.
Setting the right voltage and current limits is essential if you are to meet manufacturer specifications. Overcharging and over-discharging can also affect cycle life. A battery pack is typically cycled using a multi-channel tester that creates different charge and discharge curves, including pulse input and load.
At the same time, it can monitor and record various performance parameters of the battery, such as temperature, capacity, impedance, power output, discharge time, etc. Typically, a controlled full charge-discharge cycle takes about 5 hours. This means that it would take 208 days to test 1,000 cycles, assuming a 24/7 work week. Therefore, any continuous improvement to the battery will take a long time to verify its effect.
Since the aging process is continuous and fairly linear, it is possible to predict the life of a battery with a small number of cycles. However, for the service life of your product, it takes a lot of batteries and a long time to finally prove this. For high-power batteries, this can be very expensive.
10) Load test
Load testing is used to verify that a battery can provide the specified power when required. Usually, the load represents the conditions under which the battery will be used. It can be a constant load at the C rate, a pulsed load at a higher current rate, or in the case of an automotive battery, the load can be designed to mimic typical drive patterns.
Low-power testing is usually done with a resistive load. It may be necessary to use other techniques when testing very high power with variable loads. Ward-Leonard controllers can be used to provide a variable load profile where battery power is returned to the utility power rather than being consumed in the load.
Note that the capacity of the battery may be higher when discharged intermittently than when discharged continuously. This is because the battery is able to recover during idle periods between intermittent high-current draws.
As a result, testing battery capacity with a continuously high current draw will not necessarily result in results that are representative of real-world capacities. Load testing often needs to be performed with variable load levels.
This could be just a pulsed load, or it could be a more complex high-power load profile such as that required for an EV battery. Standard load profiles such as the Federal Urban Driving Scheme (FUDS) and Dynamic Stress Test (DST), as specified by the United States Advanced Battery Consortium (USABC), as well as the United Nations Economic Commission for Europe specification (ECE-15) and the European Ultra Urban Driving Cycle (EUDC ), have been developed to simulate driving conditions, and some manufacturers have incorporated these profiles into their test equipment.
While these standard usage cycles have been developed to provide a basis for comparison, it should be noted that typical users do not necessarily drive according to these cycles and are likely to accelerate at least twice as much as the standard allows.
3. Standards for lithium battery safety testing
For small lithium batteries, the following three standards are most commonly tested by general battery laboratories :
- The UN/DOT 38.3 5th Edition, Amendment 1 – Dangerous Goods Transport Recommendations
- 62133-2:2017 – Safety requirements for portable sealed secondary lithium batteries and batteries made from them for portable applications – Part 2: Lithium systems
- Batteries for household and commercial use – UL 2054 2nd Edition
Below is a quick overview of each.
1) AND/GIVE 38.3
Want to ship lithium batteries almost anywhere in the world by air, ship, rail, or truck? Unless you wish to be severely restricted in shipping batteries (ground transport as Class 9 Dangerous Goods), you will need to certify that your batteries pass UN/DOT 38.3.
This standard appears in the dangerous goods transport regulations of many countries and is relevant for the transport safety of all lithium metal and lithium-ion cells and batteries. Due to potential liability issues, most companies use a third-party testing laboratory to self-certify under UN/DOT 38.3.
In UN 38.3, significant environmental, mechanical, and electrical stresses are addressed in sequence (T1-T5
- T1 – Cells and packs at altitude simulation (Primary and Secondary)
- Test 2 – Batteries and cells are subjected to a thermal test (primary and secondary)
- Cells and batteries (primary and secondary) vibrate
- T4 – Cells and batteries subjected to shock (primary and secondary)
- External short circuit (primary and secondary cells, battery packs)
- T6 – Effects (primary and secondary batteries)
- T7 – Overcharged (secondary battery)
- A primary and secondary battery that has been forced to discharge (T8)
Some tests are easier to pass than others. Altitude testing is the easiest. Vibration tests, on the other hand, are intense and long-lasting: 3 hours in each of the three basic planes. The T1-T5 sequence usually has a negative cumulative effect.
2）IEC 62133
IEC 62133 is a mandatory requirement for many IEC end equipment standards and is the de facto international compliance standard. It is not necessary to repeat the UN 38.3 transport test (see previous section).
The standard includes four tests:
- 2.2 Plastic case stress
- 3.2 External short circuit
- 3.3 Free fall
- 3.6 Battery Overcharge
These tests are relatively easy to pass compared to the requirements of UN 38.3.
3）UL 2054
Many US end-equipment standards mandate compliance with the requirements of UL 2054. This is a challenging standard, involving approximately twice as many tests as the UN or IEC requirements:
- 7 Electrical Test
- 4 mechanical tests
- 4 Battery case test
- 1 Fire Exposure Test
- 2 Environmental testing
Electrical testing is the most challenging due to the inclusion of single faults and worst-case operations. Due to the overvoltage condition of the failed battery pack, abusing the overcharge test is the most difficult. There are also major failure risks in abnormal charging, forced discharging and two short-circuit tests.
UL 2054 defers all component-level testing for lithium batteries to UL 1642. Warning: Not all laboratories will accept another NRTL’s test results.
Our lab, for instance, will apply another NRTL’s battery-level UL 1642 test data to the UL 2054 test when testing batteries according to UL 2054. This saves customers time and money. We recommend avoiding NRTLs that do not follow this customer-friendly practice.
The future of UL 2054 is bleak. UL has published the first edition of UL 62133, which is fully consistent with the second edition of IEC 62133. UL 2054 and UL 62133 are essentially competing for the same testing space, even though they have very different requirements. It is still unclear when UL 62133 adoption will occur, but it will affect the future role of UL 2054 as a US compliance standard.
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4. What is a Battery Tester?
A battery tester is an electronic device used to test the total remaining capacity of a battery. Contrary to popular belief, they don’t test voltage – just remaining capacity. Every battery has a direct current. Here are common features of high-quality battery tester
- Precise control loop for the charging and discharging process.
- Highest level of current and voltage accuracy.
- Over a wide range of temperatures, maintain system accuracy.
1) Types of Battery Tester
Battery Testers can be divided into different types according to different characters.
- By Purpose
Battery impedance tester – used to test the battery to prevent battery failure. The tester evaluates the impedance, voltage, and capacity of the battery. It can identify early signs of individual cell weakness or general deterioration. It is used to indicate the general condition of the battery.
Battery Discharge Kit – This allows the battery to be tested without disconnecting it from the system. Its high discharge capacity reduces test times. Typically, it has safety features such as non-spark connections and emergency safety fuses.
Battery Ground Fault Tracker – This is used to detect ground faults in ungrounded DC battery systems very easily. It can be operated in an environment with high electrical noise. It simplifies the fault tracing process by identifying fault signature magnitudes such as resistance and capacitance parameters. It can be used in any industry where powering measurement, communication, and control equipment is critical.
Battery Voltage Monitor – Used for monitoring to indicate the status of the battery. Since rechargeable batteries have specific charge and discharge levels, if the battery voltage exceeds this level, the battery may be damaged. An easy setup and a wide voltage range make it a great choice. In addition, the device features high precision and stability for precise data acquisition.
- By Function
Wired and Wireless – For testing AAA, AA, 9V, C, D, and 1.5V types of batteries. Users can use it to test coin cell batteries used in watches, calculators, clocks, etc. Carrying it from one place to another is easy. It is suitable for home, car, bicycle, and other special situations.
Analog and Digital – Digital testers are lightweight and compact. Less time is required to evaluate the battery status compared to the analog type. The digital tester is suitable for home use.
Display – Equipped with an LCD or LED screen for displaying battery information.
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2) Various factors to consider when selecting battery testing equipment
- Hardware – material specifications and quality
- Software – usability and functionality
- Data – recording, management, and analysis
- Options – Accessibility and Accessories
- Support – Product Security and Support
3) High-quality brand battery tester
Here are some high-quality brands of battery testers:
- Fluke BAT 250 – 250 V Battery Tester
It measures 9 V, AA, AAA, C, D, and 1.5 V batteries and has safety jaws for attaching device batteries. The input voltage must be 250 volts. It does not require batteries to operate like other devices and can withstand harsh user applications.
- Amprobe BAT 250 – Battery Tester
It has a user-friendly design for one-handed use with reliable battery measurements. It has a user-friendly slider with V-shaped side brackets to hold the battery in place during testing. The tester is ideal for testing standard and rechargeable batteries. For easy reading, it has a large display. The handle is comfortable, and the measurements are accurate. It is the first choice for consistent and bug-free performance.
- Kusam Meco KM 900 – 100 V, 200 Ah High-Performance Battery Quality Analyzer
It is designed to measure internal resistance, open circuit voltage, and terminal temperature of secondary batteries. Kusam Meco uses 4 terminal methods to measure internal resistance for accurate results. This battery quality analyzer has multiple display screens, which can simultaneously display the battery’s internal resistance, voltage and temperature, and current, and temperature. Clamp adapters are used to measure AC and DC currents.
（Another Related Article: Shock vs Vibration: What’s the Difference?）
5. Security, performance, and system management
“Battery testing” can range from the characterization of the smallest batteries in portable equipment to large vehicle batteries operating at 1,000 V and beyond. Battery systems are critical to electric vehicles. Today, lithium-ion batteries are one of the most commonly used types in electric vehicles due to their high energy and power density.
Depending on the market environment, “battery” has different terms. For example, in the automotive field, depending on the state of integration in the vehicle, the electric vehicle battery as the device under test and the associated test procedures may differ if it involves battery manufacturing, module, or battery pack manufacturing.
A battery is typically a single electrochemical device, a single storage unit, with a maximum voltage range typically not exceeding 5 V. This module consists of several connected units and some other electronics to control the whole system. Modules are packaged in some way, so tests usually have the whole module as a single element.
Packs are larger elements made up of multiple modules, again connected by some wiring, and have more complex control and onboard communication electronics to communicate with other processing units, just like a vehicle.
As mentioned earlier, a test unit is not the same as a test module or test package, and test setups can vary at each stage of the manufacturing value chain. Tests may end up being different depending on the test method used, as is the case with impedance measurements.
Testing generally involves three main areas: safety testing, which is critical for systems built from multiple battery packs arranged in series/parallel topology to provide higher power density; and performance testing of cells/modules/PACKs.
The number of charge and discharge cycles, run time, and temperature are closely related; and management testing, where performance optimization and EOL test validation are key.
6. Conclusion
Since batteries are a critical component of many products, it is critical to equip each company or individual researcher with the right battery testing equipment. It can use a battery voltage recorder and battery load unit to measure various parameters of the battery, such as voltage, capacity, temperature, electrolyte density, etc.
So start finding the best battery testing equipment for your organization and protect the devices you support by preventing various types of failures.
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