Han EV collides and catches fire. Is the blade battery “overturned” or “pot” of coolant?

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Han EV collides and catches fire. Is the blade battery "overturned" or "pot" of coolant?

Source: Video network screenshot

Author  | Qin Zhangyong

Edit  | Wang Yan

More than a year ago, Wang Chuanfu had arrogantly said that the appearance of blade batteries will completely erase the word “spontaneous combustion” from the dictionary of new energy vehicles. Now in a crash test, BYD has been pushed into the limelight of public opinion because of the fire.

On July 24, the automobile media platform Dao Che Di released a video of “BYD Han EV collided with Polar Fox Alpha S at high speed, and Han EV caught fire after 2 days of standing.” In the test video, the two cars had a 50% overlap collision at a speed of 64km/h. After the collision, the engine compartments of the two cars were severely deformed, and there was no fire or explosion.

The originally seemingly unremarkable crash test was reversed afterwards. After the vehicle collided and stood still for 48 hours, the BYD Han EV burst into flames, and the entire vehicle was burnt down. According to the video host, it was determined by the fire department that it was caused by a fault in the battery’s electrical circuit.

This also makes the blade battery, which has been promoting absolute safety, regarded as a “rollover.” On July 25, BYD Auto responded to its official Weibo post saying that there are many doubts in preliminary judgments based on the information in the current video and related data in the background.

At the same time, BYD also questioned the testing standards and methods used in the video, “non-mainstream, non-authoritative, and not national and industry standards.” BYD said that it will arrange for on-site inspections and suspected investigations by technicians in the follow-up.

The “coolant” pot?
In BYD’s statement, it believes that the main doubt is that the coolant of BYD Han EV in the video (red, commonly used in the industry and conductive) and the cooling fluid of Han EV production vehicles (purple, unique to BYD, non-conductive) completely different. Therefore, BYD believes that the crashed vehicle was replaced with a conductive coolant and leaked, which caused the line to short-circuit and burn.

However, the official reply not only failed to calm the turmoil, but also caused a dispute among car owners about the color of the coolant.

Generally, for traditional fuel vehicles, the engine will have a certain amount of loss during the working process. When the loss appears in the form of heat, it needs coolant to help it dissipate heat to ensure the stable operation of the engine.

Different from fuel vehicles, the coolant of electric vehicles will also be used to cool the battery. However, due to the different technologies and materials used by the OEMs, the industry has not yet formed a unified technical evaluation system for the manufacturing of related coolants.

Han EV collides and catches fire. Is the blade battery "overturned" or "pot" of coolant?

Source: BYD

If the coolant leaks, when the coolant is conductive, it will cause a short circuit of the battery, which may cause the battery to burn if it accumulates to a certain temperature. This is why BYD has always emphasized that the purple coolant of the mass-produced Han EV is non-conductive.

In fact, it is not an exception to the “recognition and hindsight” of BYD. As early as 2011, Volt’s lithium battery started to catch fire after three weeks of side-impact testing of Volt, an electric vehicle owned by General Motors. The accident investigation found that after the collision, the battery coolant penetrated into the battery box and caused an internal short circuit, which developed into a thermal runaway.

Although the situation of Han EV and Volt is different, the fire accident of Han EV may not only be caused by the leakage of coolant. Although there is no final conclusion yet, there are indeed many reasons for the spontaneous combustion of electric vehicles.

Zhang Xiang, a researcher at the Automotive Industry Innovation Research Center of North China University of Technology, told Future Auto Daily that when a vehicle collides, the battery pack is deformed and the internal diaphragm ruptures, the electrolyte will also seep out. “When the current increases and accumulates to a certain temperature, it will cause thermal runaway of the battery pack, which is also a common cause of spontaneous combustion of electric vehicles.”

Safety has always been the key to BYD’s promotion of blade batteries. According to the official statement, the blade battery uses the more popular CTP technology to increase the volumetric specific energy density of the battery by optimizing the battery pack space. In order to prove its safety, BYD also released acupuncture test video. After acupuncture, the blade battery has no open flame, smokeless, and the surface temperature is 60 degrees.

In the video of the collision, the emperor understands that the Han EV equipped with blade batteries caught fire, indicating that only the battery cell puncture and squeeze test results cannot represent the safety performance of the battery after the battery is assembled. Otherwise, this time It should be a ternary lithium battery that caught fire.

“Testing non-compliant”

Returning to the crash test itself, BYD believes that the crash test is “non-mainstream” and “non-authoritative”.

In this test, two cars, the 2020 BYD Han EV ultra-long-endurance luxury model and the 2021 ARCFOX Polar Fox Alpha S 252S, were selected for this test, and they carried out a 50% overlap collision at a speed of 64km/h.

This crash test is similar to C-NCAP’s new two-car bump test (MPDB), which replaces the original frontal offset crash (ODB). The experimental scene of the former is closer to the real traffic accident scene, while the latter is a frontal collision test with a 40% overlapping deformable barrier. For car companies, MPDB is not only more complicated, but also more difficult.

However, there is still a lot of debate about whether the experiment is compliant or not.

Zhang Xiang told Future Auto Daily that the collision was not compliant. In his opinion, the cost of the national standard crash test room is very high. Before the vehicle crashes, sensors must be arranged on the vehicle, and data collected in real time during the entire process, including temperature, acceleration, and displacement changes, are collected by collecting a series of data. Then carry out accurate analysis. “The collision is relatively simple, it can only explain certain problems, and cannot make an accurate analysis.”

Han EV collides and catches fire. Is the blade battery "overturned" or "pot" of coolant?

Source: Network video screenshot

 

At the same time, through the video, the performance of the two cars after the collision is quite different. According to the video introduction, the entire Han EV vehicle is absorbing the kinetic energy of the collision, causing the front of the car to be seriously crushed, the anti-collision beam is broken, and many areas of the door and A-pillar have desoldering and solder joint failure. In response to this matter, BYD has not yet given a response.

However, BYD said that Han EV has been developed in strict accordance with the super five-star safety standard from the beginning of its development, and won the C-NCAP five-star safety certification with a score rate of 91.5%. Since the listing of Han EV, it has successively passed the certification of C-NCAP and China Insurance Research Institute, two major national authorities, and has become the first new energy car to be awarded the “Double Excellent Safety Certification”. The reason why Han EV has attracted much attention since its listing is precisely because it is equipped with BYD’s most proud blade battery.

At present, the collision incident has not yet been finalized. According to an industry insider, because the vehicle caught fire later, it does not directly indicate that the blade battery is unsafe. “The possible reasons behind it are complex and cannot be easily judged.” and At the same time, “whether this incident will ultimately affect consumers’ judgments requires follow-up official conclusions.”

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