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Considerations for Second Life Assessment of Electric Vehicle Batteries

With continued global growth of electric vehicles (EVs), end-of-life requirements must be considered for the batteries powering them. While a battery may no longer be useful for powering a vehicle, it typically still has around an 80 percent usable capacity, meaning that, while it is no longer useful for the needs of powering an electric vehicle, it can be repurposed for other “second life” uses, such as powering commercial appliances, medical equipment or energy storage, such as in homes or buildings utilizing solar panels.

Taking the electric battery from the automotive industry and its original use in a car to another industry for use in a completely different application is not necessarily a simple and straightforward transition. There are many considerations, challenges and processes to undertake when preparing a battery for a second life usage. This includes options for the battery itself, the intended use and environment for the battery’s second life, new and existing industry requirements, and more. It is important for electric vehicle and battery manufacturers, as well as potential second life users, to understand the challenges, implications, requirements and processes for repurposing batteries for their second life.


There are a number of ways to determine if an electric vehicle battery is past its prime and needs to be replaced. It may come from a customer complaint about lower vehicle range or during a scheduled vehicle battery upgrade. It may be determined during repair assessments, general maintenance sessions or at some other time.  Regardless of how it is determined to be obsolete for on-road use, the battery of an electric vehicle operating below optimal range must be replaced.

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Manufacturers are then faced with a decision as to what to do with the battery. The typical options are to either discard it, recycle it or repurpose it for another use. While it is an option, discarding the battery is not necessarily a simple step to take. It presents challenges in terms of landfill space and usage and how to handle the hazardous chemicals and metals present in the battery, as they will need to be disposed of properly Additionally, many regions, like the European Union, have distinct vehicle end-of-life guidelines that require a certain percentage of the car to be re-used or recycled. The EU ELV Directive, for example, requires that 85 percent of vehicle weight be reused or recycled, leaving only 15 percent of the vehicle weight available for discarding. Since batteries can account for up to 10 percent of vehicle weight, this makes recycling or repurposing a much more desirable option under the ELV Directive.

EV batteries can also be recycled, but this is not always an easy undertaking. The batteries contain heavy metals and proprietary chemical compounds. As a result, recycling EV batteries requires careful handling and can often be costly. In fact, the process itself can even be more expensive than the value of the materials pulled from the battery! For these reasons, recycling is not always the most attractive option either.

As mentioned previously, most electric vehicle batteries are still operating at around an 80 percent capacity level at their end-of-life stage. For this reason, utilities and manufacturers in other industries are starting to see a used EV battery as a low cost/high-quality power source. This opens up a number of possibilities for the battery’s use. However, before it can be used in a different industry, for another purpose or within a new product, the battery will need to be repurposed using a three-step process:

  1. Assessment—First, the battery must be assessed for fitness to be repurposed. If the battery is unfit to be used again, repurposing is simply not an option. For example, if the vehicle was in an accident at some point, the battery may have been damaged in a way that renders it unusable in the future. Engineers will need to examine the battery to ensure it can continue to be used.  Typically, only the original vehicle OEM has traceable information on the history or “state of health” of the battery, so a repurposer typically needs to access that historical information to assess the battery’s usefulness.
  2. Remanufacturing—If a battery is deemed fit for repurposing, it must then be “remanufactured” for its second life. This process will vary based on the new use of the battery. In some cases, the battery may be re-used as is, with no additional disassembly.   One option is to disassemble the battery to the module or component cell level and build a new battery from those modules or cells. A less costly, and generally simpler, process is to repurpose the battery pack as is, without any further disassembly.
  3. Recertification—Finally, it is possible that the battery will require recertification, depending on the intended second usage. This includes transportation regulations as well as any application or installation-specific building code or electrical safety regulations and standards.

Transportation: UN 38.3

In order to be transported, lithium-ion batteries must meet certain provisions laid out in the global UN 38.3 standard. This includes transportation for reassessment and to manufacturers or utilities for its new use. Samples and prototypes can be shipped as full Class 9 dangerous goods shipments, or may be shipped less restrictively, with competent authority approval, including by air.

Lithium ion battery transportation regulations don’t specifically take into account repurposed batteries. Therefore, even if the battery is being used as is, a representative set of samples may need to undergo UN 38.3 testing. Because the original manufacturer and repurposer may not be the same, the battery may need to be retested under the transportation standard. Used and/or damaged batteries also have separate packaging limitations that need to be considered.

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It is important to determine who is responsible for ensuring that batteries are to be transported in a compliant manner before proceeding with transfer and assessment. It is also a good idea to label the batteries “reconditioned” or something similar and identify who is assuming responsibility for the battery on the packaging.

To adhere to the basics of UN 38.3, it is important to maintain copies of all relevant UN 38.3 test reports from subcontractors within your supply chain. As of January 2020, a test summary for your shipments must be made available, maintaining the supporting information for UN 38.3 compliance. These test report summaries must be available from the shipper upon request. They do not need to be included in shipments; however, it may be wise to include when further transportation will occur, so that downstream shippers or distributors also have access to the compliance information.   

Always consider what level of cell, module, subassembly or battery will be offered for shipment. Identify the samples tested and the models/versions to be covered by a single test report. Be aware of model number changes, which may call the test summary into question.

Battery Reassessment: UL 1974

While a self-declaration that a battery is fit for reuse or repurposing is an option, it may create problems in the second use market if there is a lack of consistent battery assessment processes or labeling inconsistencies, or if knowledge is not shared effectively between the initial manufacturer and the repurposer/second life user. For that reason, it is strongly recommended to follow established standards and guidelines. To reassess the battery for use, UL 1974 provides the necessary guidance.

UL 1974 is a standard for the evaluation of batteries intended for a repurposed use application. It applies to battery packs, cells, modules and electrochemical capacitors, and includes steps to demonstrate that a battery can be repurposed and moved from one industry to another. It also contains considerations for knowledge of the original battery design as well as a rework/screening process. The standard also establishes guidelines for cell evaluation at the module level (when cells cannot be separated individually) and allows for various usage cases, that is, reuse, repurpose or remanufacture. These requirements allow the manufacturer to establish the state-of-health of the battery in order to proceed with further assessments and testing, which includes industry-specific considerations.

Furthermore, UL 1974 also has requirements for evaluating the battery according to end-product standards. That is, the battery must meet the safety and performance requirements set by the industry where the repurposed battery will be used, such as UL 1973 for stationary energy storage applications. As such, the related recertification process and costs must also be considered when repurposing EV batteries.

In a typical certification from a National Recognized Testing Laboratory (NRTL), the product’s manufacturing process must be audited or assessed periodically. In the case of a repurposed battery, the manufacturing has occurred in the past. Therefore, the NRTL must assess the quality control of the sorting/screening process rather than an assembly process. This ensures traceability of incoming used batteries and their related state-of-health data to assure that no “unfit” batteries are released to the second use market. For rebuilt/reconstructed batteries, both the screening process and final assembly processes must be assessed.

Other Testing/Certification Considerations

If an electric vehicle battery is being repurposed for use in a different industry, such as energy storage, power generations or commercial appliances, the battery must be assessed to the applicable safety standards for the new industry. This may include standards from the IEC, NFPA, ANSI or other industry organizations.

It is important to ensure you understand what standards and certification schemes will apply to the battery, and the testing and assessments required for certification. Work with your testing partners to build a test plan to properly evaluate the battery for its new use. This will ensure a successful transition and uphold your brand’s reputation.

Best Practices

Since the standards and guidelines continue to evolve for second-life batteries, it is important to stay informed on new developments and requirements for reuse. This includes standards around end-of-life stages for batteries, as they will impact the potential outcomes for an EV battery. It also includes new or changing standards on transporting batteries, repurposing batteries and general battery safety and compliance, as these will impact the EV battery in both its first and second lives.

It is a fact that the EV battery is an expensive and heavy piece of equipment. For these reasons, and because the used battery still offers a great deal of energy storage potential, recycling and reuse is often a preferred option at the end-of-life stage. As manufacturers seek to find a second life for EV batteries at the end of their initial use, it’s important to know not only the options but the process for repurposing a battery for new use.

Start the process of repurposing by clearly defining responsibilities for the batteries, particularly in relation to transportation and assessment. This will avoid confusion, setbacks and delays during the project. Next, determine if self-declaration of the battery’s fitness for repurposing is an option for you. If you decide that self-declaration is not in your best interest, work with a knowledgeable, trusted testing partner to build a comprehensive plan that assesses the battery for reuse and includes testing and certification for industry standards needed for the battery’s new application.

Clear communication within your organization, with testing and certification bodies, and with partners in the second life industry will also help to ensure a smooth, timely transition, allowing automotive OEMs to meet end-of-life requirements for the battery and the vehicle.

As electric vehicle use continues to increase, a growing number of EV batteries will need to be refurbished, reused and remanufactured. The key to a successful second life lies in developing and following robust certification programs and design/reuse guidelines, defining liability and responsibility for the repurposed batteries, and a rigorous screening process to ensure batteries are fit for reuse and are repurposed in a safe, effective manner.

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