April 25, 2022
Everyone knows about batteries. They’re used in laptops, tablets, cellphones, toys, hoverboards, ear buds – the list is long. Cars and trucks have always had batteries for starters, ignition, and other functions, and small vehicles like golf carts are often battery-powered.
What’s new is the proliferation of electric vehicles (EVs). Chances are that if you don’t own one yourself, you know someone who does, and their numbers will keep growing as time goes on. They’re cleaner and require less maintenance than vehicles with internal-combustion engines (ICE), and economies of scale will gradually bring down their cost.
EVs have broad advantages. To realize their full value, their battery packs need to be tested for safety and electromagnetic compatibility (EMC). Batteries use reactive compounds to generate energy, and their supporting hardware uses voltage-regulating circuitry that generate electromagnetic interference (EMI). The bigger the battery, the more important its safety. And the higher the internal electrical levels, the more important are the EMC tests.
Standards for Battery Packs
Rechargeable batteries come in different compositions depending on their application. EV batteries are lithium-ion, while smaller batteries can be lithium-ion or nickel-cadmium. International safety and EMC standards are the foundation requirements.
- UN 38.3, the UN Manual of Tests and Criteria Part III Subsection 38.3 paragraph 38.3.5, is the global requirement for domestic and international transportation of hazardous materials, like lithium-ion batteries. Batteries need to be certified to UN 38.3 before being allowed to ship by air, sea, rail, or roadway.
- IEC 62281:2019, Safety of primary and secondary lithium cells and batteries during transport, contains requirements and test methods to assure safe transportation for lithium-ion batteries.
- MIL-PRF 32383/4A, Battery, Rechargeable, Sealed, Lithium-Ion, BB-2525 and BB-3525, sets requirements for sealed rechargeable batteries designed for use in US military portable devices. Tests include conformability, over-flex, immersion, and nail penetration.
- UL 1642, Lithium Batteries, is a safety standard describing tests and characterization of lithium-ion batteries, especially those defined as user-replaceable. UL 1642 covers safety performance when operating in a product and is non-compulsory in the US.
- UL 62133, Secondary Cells and Batteries Containing Alkaline or Other Non-Acid Electrolytes – Safety Requirements for Portable Sealed Secondary Cells, and for Batteries Made From Them, for Use in Portable Applications, is the safety standard for batteries made with alkaline or other non-acid electrolytes. Because of alkaline batteries’ widespread use, UL 62133 is the de facto standard for international compliance.
- SAE J2464, Electric and Hybrid Electric Vehicle Rechargeable Energy Storage System (RESS) Safety and Abuse Testing, is the recommended practice for testing rechargeable systems to conditions beyond their normal operating range.
- MIL-PRF-32565, Performance Specification Battery, Rechargeable, Sealed, 6T Lithium-Ion, is the performance and safety standard for 6T form-factor lithium-ion batteries.
Battery Testing at Elite
Rechargeable batteries are typically used in applications where long life and safe operation are at a premium. The environmental stress tests called for in the standards listed above fall into several areas of Elite’s expertise, as shown in the table to the right:
A wide variety of tests performed at Elite come under these rules, along with other specific requirements for certain manufacturers or battery applications.
- Temperature Exposure, in which the batteries are placed in a temperature-extreme environment while under operating conditions defined in the applicable standard.
- Thermal Runaway, which is a top-of-mind concern among battery manufacturers. Elite’s thermal imaging camera allows precise tracking of the battery’s thermal condition.
- Ingress Protection (IP), from levels IP1 to IP9, depending on the battery’s size.
- Altitude Testing, in which the battery is placed in a chamber and subjected to varying levels of air pressure to simulate high-altitude conditions. The operating condition of the battery during the test is specified the applicable standard.
- Vibration & Shock Testing: EV battery packs, along with other industrial-application rechargeable batteries, endure almost continuous vibration and mechanical shock in actual use. The standards listed above, along with specific manufacturer requirements, define the operating conditions and vibration levels applicable to the battery type.
- Overvoltage, Short Circuit, and Overcharge Testing: Electrical malfunctions are an obvious risk to an electrical-storage system. Tests have defined that subject the batteries to short circuits, over-charging, and over-voltage levels, checking for hazards during the tests.
- Specialized Testing: crush, nail penetration, immersion, projectile – these are among the specialized tests often required by a vehicle manufacturer or other OEM. The goal in each test is safety under conditions of abuse.
EMC Standards Applicable to Battery Packs
EV battery packs and their associated hardware need to meet electromagnetic compatibility (EMC) requirements, both because of the risk of EM emissions and the potential vulnerability of the control circuitry to ambient EM fields and transients.
The applicable standards can vary depending on the application of the battery pack and the specific vehicle manufacturer’s requirements, but several broad standards are likely to apply:
- The EU CE Mark requirements, covering both emissions and immunity to EM fields, electrostatic discharge (ESD), radiated and conducted immunity.
- MIL-STD-461, covering many of the same phenomena as the CE Mark requirements, with some additional test features.
- The SAE series of EMC standards, covering EM field phenomena, along with AC power line electric field immunity.
Especially in the automotive industry, individual manufacturers are likely to have their own specifications and test procedures in addition to the baseline regulatory standards.
Contact Elite to discuss which standards and type of test is best suited to meet your product’s needs.
Planning a Battery-Pack EMC Test
As described in Elite’s blog series, Ten Steps to a Successful Vehicle EMC Test, the first steps are to identify the product’s intended markets and the standards that apply. The foundational standards will be CISPR 12 and CISPR 25, covering radiated and conducted EMI, along with UN 38.3 for transporting and shipping lithium-ion batteries
Elite has decades of experience testing various forms of battery packs. John Gondek has been among Elite’s battery-test engineers and now serves as a customer interface to plan the tests and answer questions that arise. John has developed a series of items to be observed when planning and executing a battery test:
- Remember: safety first. The object of tests performed under these standards is to ensure safe operation of what can be a combustible device. Always respect batteries when during transport and during a test.
- Define how the battery samples are to be transported. Check with your courier on any shipping restrictions or handling requirements. How are they being prepared for shipment? What charge state are they in? These questions are fundamental to the batteries’ safe handling and shipping.
- Provide details on battery chemistry, pack design, number of cells, and information on protective circuits.
- Provide wiring diagrams and pin connection details.
- Define the battery state during the test. For a meaningful test, the battery needs to be in a proper state of charge, both for testing and charge cycling. Clients should provide specifications and tolerances for all relevant performance metrics.
- Monitor battery performance. During the test, the battery needs to be monitored for its pass/fail state. Parameters such as voltage levels, cycle time, and changes in its mass need to be observed and noted for changes that could be regarded as failures.
Elite’s Emerging Battery-Test Capabilities
To answer the needs of the EV industry, Elite is adding new services and equipment that meet the growing demand and the evolving standards. One example is the 28,000-pound vibration table with a 5’ x 5’ slip table surface now in place, providing a mechanical testing resource to handle larger battery packs. Watch for more details in a future blog.
And stay tuned for more on our upcoming battery-testing chamber that will provide the means to meet the evolving test standards.
The remarkable growth of electric vehicles has brought the need for battery testing into sharp focus. Contact Elite’s experts to start planning your tests and get answers to your questions. Elite’s deep expertise, reputation for timeliness, and trusted results will help you reach your market with confidence.