Just over halfway through April, the hottest season has not yet come, and new energy vehicles have "caught fire" first.
Only this time, the new energy vehicles "fire" is not sales, but burn themselves. On March 28, a Xiaopeng G3 spontaneously combusted in a small area in Longhua District, Shenzhen, burning the whole vehicle to only the skeleton; on April 5, an Aichi U5 spontaneously combusted at a charging station in Chengdu's Jinjiang District, which caused widespread concern.
In just one week, two different brands of new energy vehicles have spontaneous combustion accidents, once again allowing the market to examine the safety of new energy vehicles.
In the past year, spontaneous combustion news of new energy vehicles is not uncommon, but correspondingly, the sales of new energy vehicles have reached a new high, BYD has taken the lead in announcing the suspension of fuel vehicles in a high profile, and a number of car companies have launched a timetable for stopping production of fuel vehicles.
This undoubtedly indicates that new energy vehicles, represented by electric vehicles, will become the future of the domestic automobile market. The future is getting closer and closer, but the new energy vehicles that are constantly "burning" seem to be not ready?
This article will explore and interpret the frequent fire phenomenon of new energy vehicles through the following questions, and try to find the answer to the future "flame stopping" of new energy vehicles:
1. How often are fire accidents in new energy vehicles and how many brands are covered?
2. Hundreds of fires, what is the most important reason for the combustion of new energy vehicles?
3. The future of new energy is coming, how should car companies find a safe way in rapid development?
New energy vehicle companies, can not escape the combustion
How often do new energy vehicles catch fire? If you take news reports as a standard, in the past two years, there have been a total of 86 reported new energy vehicle fire accidents, an average of about once a week.
But the fire accidents that have appeared in the news are only part of the "combustion" of new energy vehicles. According to the latest data given by the Fire and Rescue Bureau of the Ministry of Emergency Management on April 3 this year, in the first quarter of this year, there were 640 new energy vehicle fires, an increase of 32% year-on-year, equivalent to an average of 7 new energy vehicles "burning" every day.
In addition to the staggering number of fire accidents, in terms of brand, the combustion of new energy vehicles also shows a trend of "rain and dew". Whether it is the international big factory Tesla, the domestic big factory BYD, "Wei Xiaoli" and other new car-making forces, or the traditional car factories such as GAC and BAIC, none of them can escape the "fate" of combustion.
Multi-brand new energy vehicles are difficult to escape the fire, and even-style watchmaking
Among the 86 fire accidents we counted according to news reports, BYD ranked first with 11 fire accidents, involving E5, E2, Tang, Qin and other models. Another well-known brand Tesla accounted for 5 fire accidents, including model 3 and Model S, of which 3 were self-fires.
The most recent BYD fire came in October 2021, when a BYD Han was seen emitting a lot of white smoke on the side of the road on the Shenzhen Shuiguan Expressway. The most recent fire in Tesla was also in October 2021, when a Model S spontaneously spontaneously combusted during stationary parking, and the vehicle was burned into an empty shell.
In terms of new car-making forces, there are also 5 ideal fire accidents, and the models are ideal ONE. There were 4 fire accidents in Xiaopeng Automobile, of which 3 were G3 models, all of which were self-fired, and 1 was P7. There were 1 fire accident in Weilai, and the model number was EC6.
The most recent fire in the new forces was the Xiaopeng Automobile G3, which spontaneously combusted in parking on March 28 this year, and ideal ONE, which is owned by Ideal, also suffered a spontaneous combustion accident during parking on February 25 this year.
An ideal ONE spontaneous combustion in February this year Figure/Network
In addition, there are many models of second-tier car-making emerging power brands, which are on the "combustion list", such as WM Motor's EX5, and there are 4 fire accidents, all of which are spontaneous combustion. The two fires of Yundu automobiles were also spontaneous combustion.
Spontaneous combustion statistics of new energy vehicle brands (incomplete statistics)
The new energy vehicles of traditional car manufacturers are not exempt from the vulgarity, and GAC Aean, which has long occupied the top of the sales list of new energy vehicles, has burned as many as 8 times in the past two years, except for two times when the reason is unknown. BAIC BJEV's EU5, EX360 and other models have caught fire 6 times in the past two years, and 5 times have spontaneous combustion.
Chery's small ants, Arrizo and other models have spontaneous combustion three times. The 4 fires of SAIC Roewe and the 3 fires of Changan Automobile are basically spontaneous combustion.
In addition to the above-mentioned brands with a large number of fire accidents, new energy vehicles of Volkswagen, WEY, Aichi, Dongfeng, FAW, Zotye, Changan, Great Wall and other brands have also had fire and spontaneous combustion accidents. The total number of car brands involved is 30.
Although some brands that have sold well in the past year, such as Nezha and Zero Run, have not had spontaneous combustion accidents. However, the brand distribution of combustion accidents of new energy vehicles does not show a concentrated trend. Therefore, in the process of analyzing the combustion accident of new energy vehicles, we cannot simply attribute the accident to the design or structure defects of a single brand.
So, throughout nearly 30 brands, there were more than 600 new energy vehicle fires in the first quarter, what are the specific reasons? What is the main reason?
Cause of fire: Batteries bear the brunt
Among the 86 reported new energy vehicle fires in our statistics, the cause of the accident and the situation at that time were different. The most important four types of vehicle states are: fire during charging, fire while driving, fire when standing, and fire after collision.
In the state of fire of these four types of vehicles, in addition to the 7 accidents of unknown cause, the number of accidents that caught fire during standing was 31, the number of accidents that caught fire (including the charging pile fire) during charging was 22, and the number of accidents that caught fire during driving was 20.
There were only 6 accidents or fires after a collision.
Statistics of fire status of new energy vehicles Parity mapping
The number of accidents that catch fire when new energy vehicles are stationary accounts for 38.8% of fire accidents of known cause, which is diametrically opposed to the state in which fuel vehicles often catch fire because of accidents or collisions. The number of accidents that caught fire during charging accounted for 27.5%, which also shows that the Internet often blames the cause of the fire of new energy vehicles on the battery, which is not unfounded.
At the Beijing Institute of Technology's Automotive Electrification Academic Exchange Forum in July 2021, the Beijing Institute of Technology Laboratory classified the state of vehicles that caught fire in new energy vehicles at that time, of which the proportion of fires in the stationary state was 38.5%, and the proportion of fires in the charging state was 27.5%, which was the same magnitude as the number of reported fire accidents in the past two years according to jioupai.
Wei Zhongbao, the keynote speaker, said at the time: "We were very surprised, in the static state, the accident of new energy vehicle fire has increased year by year, especially in the past 3 years, now accounting for 38% of the entire fire accident." ”
At the forum, the relevant laboratory of Beijing Institute of Technology also classified the causes of fire accidents, and the data showed that the proportion of fires caused by battery failures reached 33%, the fire caused by chassis collisions or traffic accidents accounted for 15.4%, the user modification caused by driving or standing fires accounted for 12%, and the electronic and electrical failures caused fires accounted for 11%.
Statistical map/network of The State and Causes of Fires at Northern Polytechnic University
It can be seen that in addition to the fire caused by the failure of the battery itself, the chassis collision seems to be an important cause of the fire.
However, Cui Dongshu, an expert on new energy vehicles and secretary general of the China Association of Automobile Manufacturers, once said in an interview with Burning Finance that when a car chassis collides, the first thing is that the cells or high-voltage devices in the battery pack will be squeezed or punctured, which will then cause other components to short circuit in the collision, and the internal temperature of the battery will rise to thermal runaway, thus causing a fire.
Coincidentally, for fires in the standing state of increasing proportions, the industry also tends to attribute them to batteries.
Expert Wei Zhongbao previously said at the forum: "There is no unified statement in the industry for the fire in a static condition, and we infer that the damage caused by the lithium reaction of the power battery during the long-term service process must be an important cause." The imperfection and inaccuracy of the monitoring and protection strategies of the power battery will also lead to the occurrence of power battery system accidents under the shutdown state. ”
Lithium reaction is the fatal culprit that causes the internal resistance of lithium-ion batteries to increase, capacity attenuation, and decrease the efficiency of Coulomb, which will greatly shorten the cycle life of the battery, and may cause catastrophic consequences such as combustion and explosion.
Whether it is the ternary lithium battery that occupies the mainstream in the world, or the lithium iron phosphate battery that has quietly risen in recent years, it is limited by the characteristics in the short term, and it is difficult to avoid the lithium reaction and the formation of lithium dendrites, and can only be suppressed from charging and discharging and controlling the temperature environment.
In the 86 cases of new energy vehicle fires we counted, it can be seen that extreme high and low temperatures may also be important causes of fires.
From May to September, in the traditional high temperature months, a total of 57 new energy vehicle fires were reported, accounting for 66%. Previously, there were also media reports that in the ultra-low temperature environment, when the new energy vehicle battery uses DC fast charging, if the electronic control system is relatively backward and fails to preheat the battery, the battery will have the risk of fire.
In addition, the "new energy" of online ride-hailing has also brought certain hidden dangers, according to the data of the Ministry of Communications' online ride-hailing supervision platform, the proportion of new energy vehicles registered on the Didi platform in 2020 has reached 14-20%, and it is still growing.
The difference between online ride-hailing cars and private cars, their utilization rate, average daily mileage, and daily load are significantly higher than those of private cars. The charging time of its demand is shorter, and it is more inclined to use high-power fast charging, and it will be frequently charged and discharged during use, which will aggravate battery aging and lithium evolution reaction.
In this regard, Wang Zidong, deputy secretary-general of the China Automotive Power Industry Innovation Alliance, mentioned: "Some car companies are forced by sales pressure to put models sold to the C-end market on the B-end market. Due to the high load characteristics of operating vehicles, car companies still need to modify these vehicles to reduce the probability of accidents. ”
Combined with the situation of vehicle fire and the statements of the above experts, it can be seen that the current causes of fire of new energy vehicles are diversified, the battery itself is aging, external collisions, extreme temperatures, electronic control systems, and the high load of operating vehicles may lead to the fire of new energy vehicles.
But it is not difficult for us to find that what eventually causes the fire is often the battery pack built into the new energy vehicle.
This fragile, flammable and explosive, occupies a lot of the volume of the whole vehicle, and is often the whole closed and can not directly extinguish the fire of the "energy source", far from the perfect control of new energy vehicle companies.
All the way down, how to ensure safety?
On the one hand, new energy vehicles that frequently catch fire, on the other hand, new energy vehicle companies and battery manufacturers are still tirelessly promoting the progress of battery technology in order to maintain long battery life.
Just on April 11, Tesla announced that the first Tesla Model Y with 4680 ternary lithium batteries has begun to be officially delivered, and its energy density has increased to a staggering 300KWh/kg. In recent years, BYD's lithium iron phosphate blade battery has also reached an energy density of 140-180Wh/kg.
BYD's blade battery figure/network
The cell energy density of the battery is greatly improved, which is often accompanied by a decrease in the stability of the battery cell, which may further increase the "runaway risk" of the battery pack. In addition, the sales of new energy vehicles that have continued to grow in recent years have increased with the increase in the use time, and the loss of batteries is also increasing.
How should new energy vehicle companies, which are developing rapidly on the two roads of market and technology, ensure safety in this context?
Judging from the report, "locking electricity" is probably an operation jointly adopted by many car companies. According to a number of media reports, Tesla, WM, GAC Aean, Xiaopeng and other new energy vehicle brands are suspected of locking the car's power through system OTA upgrades.
However, this is bound to reduce the endurance of the model and infringe on the consumer's right to know. Last year, a large number of Xiaopeng P7 owners said that after an OTA, the original 80KWh battery pack could only be charged with less than 70KWh of electricity, suspected of being locked, and then concentrated on the black cat complaint platform to protect rights.
Xiaopeng car owner complaint lock electricity picture / black cat complaint
Cheng Duanqian, vice minister of the China Automobile Research Institute Data Center, also said about the power lock: "Power locking is only a remedial measure, and should not be used as a conventional means, which will only bring negative effects to the industry."
Therefore, locking electricity is obviously not the ultimate answer for new energy vehicle companies to avoid the risk of fire and ensure the safety of car owners.
For some old models that are not easy to replace parts, car companies should take the initiative to strengthen the maintenance of key components and timely discover the fire hazards caused by battery pack loss.
In recent years, the replacement of power by many car companies is also one of the ways to ensure the health and safety of battery packs. It is reported that Weilai, Geely two vehicle companies, as well as battery supplier "Ningwang" Ningde era, are vigorously promoting the power exchange model.
In view of the risk of battery pack loss caused by the high load characteristics of operating vehicles, BAIC and third-party operator Aodong have also set up a number of substations for commercial operators.
In addition, in terms of the strength of the vehicle's BMS battery management system and battery pack shell, car companies also have a certain amount of room for upgrading. For example, the BMS battery management system for the whole vehicle is overcharge/overdischarge protection, high voltage interlock detection, and high voltage insulation detection is temporarily insufficient.
Automotive BMS Schematic Diagram /Renesas Semiconductor
In terms of the key battery pack protection shell, at present, many car companies use aluminum alloy material structure, strength, stiffness and sealing performance under the premise of pursuing lightweight, but there is still a certain gap with the strength of heavier steel shells. In addition, some enterprises use glass fiber, SMC and other mass production processes are not yet mature lightweight composite materials.
In the future, new energy vehicle companies also need to find a more accurate balance between lightweight and safety, and strive to further improve the strength of the battery pack shell under the premise of maintaining lightweight, so as to ensure its higher safety in the event of accidents and impacts.
The most important point may be that Wang Zidong, deputy secretary-general of the China Automotive Power Industry Innovation Alliance, mentioned in an interview with Cheyun Network: "Before mastering the law of lithium battery fire, it is crucial to control the energy density of the battery. ”
At this time, look back at the new forms and high energy density battery packs adopted by various new energy vehicle companies for long-term battery life. We are afraid that for a while and a half we will not be able to dispel the safety concerns about new energy vehicles.
Write at the end
In 2021, China's new energy vehicle production is 3.545 million units, an increase of 1.6 times year-on-year, new energy vehicles represented by electric energy are rising rapidly, and more and more new energy vehicles are galloping on every street.
Compared with fuel vehicles, new energy vehicles have many advantages such as energy saving, environmental protection and driving performance. However, the frequent fires of new energy vehicles are also reminding everyone that whether it is the core component battery pack of the car or the loss caused by the long-term use of the old model, it is far from being perfectly controlled by the car company.
In the foreseeable future, new energy vehicles will also usher in more consumers. While bringing consumers a comfortable experience with excellent driving performance, we also hope that new energy vehicle companies will pay more attention to safety and bring everyone a safe and reliable new energy future.
Resources:
1. "Why is the fire incident of new energy vehicles always without results?" Cheyun Network;
2. "New energy vehicles, why love spontaneous combustion?" "Burning Finance;
3. "New energy vehicles, spontaneous combustion problem "vaguely" is still blocked between the ideal and reality", play car pie;
4. "Nearly 40% of electric vehicle fires occur in a static state Experts say technical problems have yet to be overcome", Economic Observer.