Recently, the State Administration for Market Regulation issued new requirements regarding the "three guarantees" and recalls for new energy vehicles, signifying a continuously improving market environment for these vehicles. It is important to note that safety is paramount in the process of regulating the market. As Shi Jianhua, Deputy Secretary-General of the China Association of Automobile Manufacturers, emphasized, with the increasing number of new energy vehicles on the road, safety must be given high priority. Only by ensuring safety can the better development of new energy vehicles be truly promoted. Among the many safety issues, charging safety, as a directly related aspect of users' daily operations, not only faces challenges in improving safety awareness but also inadequate operational standardization.
Surveys show that among the numerous electric vehicle fires and spontaneous combustion incidents, those occurring during charging account for the highest proportion. Yu Dexiang, chairman of TELD, the largest charging pile operator in China, even revealed that TELD has prevented tens of thousands of safety incidents through strict control of charging safety. Charging safety has become crucial to the safe operation of new energy vehicles.
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Charging factors are strongly correlated with vehicle spontaneous combustion accidents.
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Shao Zhehai, chief scientist of Potevio New Energy, shared data with reporters showing that charging-related factors are a major cause of fires in new energy vehicles. Among numerous spontaneous combustion incidents, those caused by charging factors account for 31%, ranking first among all factors. "A preliminary risk monitoring test of charging equipment products in 2018 showed that nearly 50 AC charging devices were compared with relevant safety items in current standards, but the compliance rate with all requirements was less than 50%," said Shao Zhehai. He explained that the main problems with AC charging equipment include residual current protection not meeting national standards, lack of output overload protection, lack of continuous monitoring of protective grounding conductors, and low pass rate for the IP×4 waterproof rating of the charging pile. The main problems with DC charging equipment are that charging sequence and control do not meet national standards, untimely response to demands, poor communication protocol consistency, non-compliance with interoperability standards, charging interface structures such as electronic locks not meeting national standards, and EMC of the charging equipment itself not meeting national standards.
In the 2017 interoperability evaluation activity of the China Electric Vehicle Charging Infrastructure Promotion Alliance (hereinafter referred to as "CEPA"), on-site testing was conducted on recommended vehicles and charging equipment. The success rate of AC charging equipment for one-time charging was 94%, while the success rate of DC charging equipment for one-time charging was only 75%.
Wang Zidong, deputy secretary-general of the China Automotive Power Battery Industry Innovation Alliance, also stated that frequent accidents during use, especially during charging, are one of the main safety hazards of electric vehicles.
During its inspections, the China Charging Industry Association (CCIA) found that some charging equipment had starting inrush currents exceeding 500A, lacked insulation testing, and only a few charging facility operators had installed independent monitoring devices at their stations. Furthermore, only some charging facilities in underground parking lots were equipped with dry powder fire extinguishers. These safety hazards make charging-related factors one of the biggest causes of fires involving new energy vehicles. "These existing problems pose many safety risks to electric vehicle charging. Therefore, safe charging has attracted widespread attention across the industry. Whether from the perspective of curbing electric vehicle battery combustion, improving charging service capabilities, or promoting the healthy development of the new energy vehicle industry, further improvements in charging safety are necessary," said Shao Zhehai.
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Charging safety is a systemic project.
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"The 'Electric Vehicle Safety Guidelines' (hereinafter referred to as the 'Guidelines') systematically regulates potential issues in the charging process at three levels: vehicle access, infrastructure, and operation and maintenance services," explained Shao Zhehai. At the vehicle access level, the guidelines focus on direct charging interfaces between vehicles and charging piles, as well as communication information. At the infrastructure level, the guidelines primarily address the functional entities of charging facilities, including conductive charging, battery swapping equipment, power distribution equipment, and supporting facilities and security systems at charging stations. At the operation and maintenance service level, the guidelines provide detailed regulations on operation management platforms, software and data storage, operation and maintenance procedures, and management. Shao Zhehai emphasized, "We hope to create a guiding document for charging safety in the industry, establishing a safety baseline for improving the design and manufacturing quality of charging equipment; providing a basic standard for safe charging operations; offering a common reference for cross-industry safety technology collaboration between electric vehicles and charging facilities; and providing a directional guideline for the development of charging technology and the deepening of standards research."
Furthermore, big data can also be applied to the charging field. It's not only applicable to data monitoring during the operation of new energy vehicles, but also to the charging sector. Yu Dexiang shared data from TELD's big data cloud platform with reporters. This data shows that TELD conducted over 20 million safety monitoring and protection checks during charging processes in 2018, covering 137 car brands and 885 models, triggering 258,000 proactive protection actions (actively terminating charging), accounting for 1.04%, and estimated to have prevented 20-25 major accidents. Through TELD's "police + doctor" data cloud platform, vehicles can undergo simultaneous health checks during charging, reducing potential safety hazards through prevention.
Shao Zhehai emphasized that achieving charging safety requires strengthening research on functional safety technologies, further establishing research on functional safety objectives and safety risk boundaries, and coordinating with research on power battery charging characteristics and battery failure mechanisms; tracking and improving safety testing standards for power supply equipment, and implementing technical specifications for on-site inspection of charging equipment; in terms of information security, extending from current boundary security technology research to in-depth security research, and improving relevant standards. Simultaneously, it is necessary to conduct corresponding safety technology research in conjunction with the rise of high-power and wireless charging applications, and to quantify indicators. "The factors affecting charging safety are relatively complex, and there is room for improvement in every aspect." As Shao Zhehai stated, charging safety is a systematic project that requires comprehensive and coordinated advancement.
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Fast charging affects battery life.
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"Considering that a significant portion of electric vehicle safety accidents occur during and after charging, we believe there is a correlation between electric vehicle charging and the probability of safety accidents. Based on this conclusion, we believe the industry needs to strengthen research on charging methods to improve battery pack safety and lifespan. In particular, fast charging can easily cause dendrite formation in lithium batteries, thus affecting the safety and lifespan of the battery system. Therefore, we propose that, given the current lack of experience with fast charging technology, fast charging of electric vehicles is not recommended," said Wang Zidong. He added that regarding charging safety, there are not only issues of awareness but also problems with the definition of responsibility by operating companies. Some companies have suggested that the guidelines should not include requirements on end-user charging behavior and habits. However, charging safety is not only a test of equipment but also largely related to operation and user usage. Especially now, most charging stations are developing towards unmanned and intelligent operation, and charging behavior and habits will have a significant impact on charging safety. This requires joint efforts from users and relevant companies.
However, some argue that batteries with fast-charging capabilities are more widely used in the market, and a variety of product approaches should be considered, rather than a one-size-fits-all approach. Wang Zidong told reporters that after thorough discussion, the guidelines stipulate that the charging speed of lithium-ion batteries is strongly correlated with their lifespan. For battery packs without fast-charging capabilities, the use of fast charging should be reduced when conditions permit, and lower charging rates should be chosen whenever possible. There is a certain conflict between fast charging and safety with lithium-ion batteries. Not only do the guidelines need to provide guidance, but users also need to correctly handle the relationship between charging speed and safety, minimizing the use of fast charging to ensure vehicle safety.
