The global market for advanced electrified vehicles (xEV) continues to expand. Original equipment manufacturers (OEMs) and developers face a growing number of regulations and standards addressing the safety and performance of rechargeable battery systems. Darryl Fleger, vice president and global head of transportation services at testing body TÜV SÜD, explains the key aspects and the specific requirements that apply to xEV batteries and battery systems for gaining market access in the EU, the US, China and other major markets.
Research firm LMC Automotive reported that its global light vehicle selling rate was 84 million units per year in November 2022, down from 85 million units per year in October. The year-to-date figure was less than 1% down on the corresponding period in 2021 (because of a weak base due to the COVID-19 pandemic and supply chain shortages).
The Benzinga website says the global EV market is expected to grow from 12.7 million units in 2021 to 106.6 million units by 2027 at a 41.8% CAGR between 2022 and 2027.
Government subsidies and programmes to reduce carbon emissions have been a major contributor to increased sales. But lingering concerns about long-term security emphasise the role of innovative technologies and sustainable solutions to address the global climate crisis. Therefore, continuous innovations in batteries and battery systems are a crucial factor for the acceptance of electric cars.
However, the development of new battery technologies and designs comes with several challenges. These include:
- Battery performance: does the battery meet specifications in terms of the delivered energy? Are the common charge and discharge rates met during normal operation and is the specified range achieved?
- Battery maintenance: how often does the battery need to be maintained to perform as expected? Are trained technicians needed for maintenance?
- Environmental aspects: is the battery designed to operate in high and low temperatures or humidity? Do extreme weather events, such as flooding, affect safety?
- Sustainability: are the main components and chemicals of the battery recyclable? Can the battery serve in other applications if it is no longer qualified for an xEV?
These and other factors are not only important for safe operation. In a highly competitive market, even non-safety-related failures or weak battery performance can severely damage a brand’s reputation.
Joint frameworks accelerate market access
Across the world’s major automotive markets, different sets of regulations and standards outline the basic requirements for system performance and safety. In many countries, however, the approval structures for xEVs and their components are still under development so requirements may change frequently. In addition, while some requirements in the product testing and approval process are similar, there are sometimes significant differences in detail. This may involve changes to the standard audit protocol or additional tests.
Seeking to build a common regulatory framework for sustainable transportation, the World Forum for Harmonisation of Vehicle Regulations within the United Nations Economic Commission for Europe (UNECE) has issued more than 150 prescriptions. They cover various aspects of vehicle safety, energy efficiency and environmental protection.
The Forum first had mainly a European scope. With the active participation of countries on all continents since the year 2000 it has gained global significance. More than 50 countries have now joined the forum and thereby committed to mutually acknowledge type approvals and certificates of conformity.
UNECE Regulation No. 100 (approval of vehicles with regard to specific requirements for the electric power train) – usually referred to as R100 – is a widely accepted standard for rechargeable energy storage systems (REESS) in xEVs. It contains several specific tests for REESS and rechargeable battery packs. The essential requirements are given in section 6. Annex 8 describes the specific procedures to assess the safety and integrity of the battery pack.
The tests simulate, for example, severe temperature changes and typical vibrations that affect a vehicle during normal operation. The mechanical integrity is furthermore examined under inertial and contact loads, as they can occur in an accident. In addition, fire resistance and protective functions against short circuits, overheating, overcharging, and deep discharging are measured.
All xEV batteries and battery systems that meet the safety requirements of the R100 and have been type-approved in one of the Forum’s signatory countries can generally be imported, sold, and used in other signatory countries. In practice, however, some obstacles may arise.
Understand and consider regional differences
First, although the type approvals issued in the signatory countries are in theory legally equivalent, the underlying approval practices sometimes differ significantly. Some automotive manufacturers certainly welcome a stricter approval process for supplier components. But for battery OEMs, this implies prolonged and elaborate testing.
Second, while all EU member states along with New Zealand, Japan and Australia have signed the agreement, other major automotive markets are not represented. These include the US, Canada, and China – one of the largest and fastest growing markets for xEVs. OEMs of xEV batteries and battery systems seeking to access these markets may therefore need to conduct further testing and meet additional requirements to demonstrate compliance with the relevant local regulations.
The European Union is an important gateway to the global automotive market for manufacturers of xEV batteries and battery systems. Regulation (EU) 2018/858, which outlines a framework for the type approval of most motor vehicles, systems, and components in the EU, explicitly refers to the UNECE regulations and confirms their equivalence with the EU Directives (Article 58).
Although demonstrating compliance with the requirements of the R100 is an essential part of the approval, manufacturers must go further to obtain EU type approval. These include selecting one of the three possible assessment procedures under the directive and preparing the required documentation. That consists of detailed technical specifications, drawings, photographs and test reports. A recognised “technical service” must carry out or at least observe the tests. Then, the approval authority reviews the results and assigns a registration number along with an E-mark.
In the US, the National Highway Transportation and Safety Administration (NHTSA) regulates the safety requirements for motor vehicles. The NHTSA has defined more than 50 Federal Motor Vehicle Safety Standards (FMVSS). They cover a wide range of vehicle systems and components. Manufacturers of xEV battery systems must self-certify to FMVSS 305 on electrolyte spillage and electrical shock protection.
This standard describes the requirements for limiting electrolyte leakage and retention from electrical energy storage devices and converters, as well as for protection against electric shock during normal operation and in the event of accidents.
Self-certification must be based on trustworthy test data. Therefore, most manufacturers engage independent testing organisations to perform the required tests. Many OEMs also test their products against the R100 requirements. This demonstrates that the battery meets “state of the art” design criteria, which is a procurement requirement of some US vehicle manufacturers. In turn, the potential liability due to a defective product design is reduced.
The Canadian Motor Vehicle Safety Standards (CMVSS) generally align with the corresponding US standards. The self-certification process is essentially similar, but product labels and manuals must be provided in French as well as English.
China is the largest automotive market in the world and has some of the most comprehensive legal requirements for xEV safety. The Chinese Ministry of Industry and Information Technology (MIIT) strives to align its requirements with international regulations and standards. This includes the UNECE Global Technical Regulation (GTR) No. 20 on electric vehicle safety. Nevertheless, major differences exist.
In China, the approval procedure refers to the battery as a component. This means that the battery itself cannot be homologated without being involved in an approval procedure for the entire vehicle. Thus, a battery manufacturer cannot homologate its own product, but can test it according to the safety requirements for electric vehicle traction batteries as described in the GB 38031-2020 standard for traction battery safety. The resulting test certificate can then be brought in for the OEM’s approval of the complete vehicle. The battery tests must be conducted by a third-party testing laboratory accredited by the MIIT. Based on the test report, the MIIT issues the China Compulsory Certificate (CCC) and registers the component for use.
Taiwan is also not a signatory to the World Forum Agreement. The Ministry of Transport and Communications (MOTC) has published nearly 150 separate Vehicle Safety Test Guidelines (VSTDs) covering safety aspects of most vehicle systems and components. The homologation process to obtain type approval requires that all tests be carried out by a MOTC accredited technical service provider or testing laboratory.
Assessing the safety and performance of rechargeable batteries and battery systems is a critical element in the design and development of xEVs and xEV technologies. International standards contribute to improved safety and acceptance. Common frameworks ease market access in many countries.
However, in many large automotive markets, manufacturers also face complex challenges. Cooperation with expert service providers helps to identify difficulties in advance and solve them efficiently. As the only company with a global network of battery testing laboratories, TÜV SÜD supports manufacturers in validating the safety and performance of their products. Substantial technical advice and certifications help to pass the approval process in the world’s most important markets.