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A government investigation revealed that the cause of the subsequent fires in Hyundai’s Kona electric vehicle is likely an internal short circuit due to faulty battery cell manufacturing (negative electrode tab bending).
On the 24th, the Ministry of Land, Infrastructure and Transport announced that it would voluntarily take corrective action (recall) after a manufacturing defect was found in 26,699 vehicles of three car models, including the Kona electric car manufactured and sold by Hyundai Motor. Company. The recall targets a total of 26,699 units, including 25,083 Kona electric cars, 1,314 Ionic electric cars and 302 electric buses.
According to the Ministry of Land, Infrastructure and Transportation, some of the high-voltage batteries initially produced at LG Energy Solutions’ Nanjing plant in China (September 2017-July 2019) among the batteries used in these three vehicle models were tripped due to short circuit due to cell manufacturing failure Confirmed possibility of occurrence. Consequently, these three models will begin corrective action (recall) to replace the entire high-voltage battery system (BSA) from the 29th of next month. This measure is to compensate for a fire that occurred in a Kona electric vehicle that had already been recalled once in Daegu on the 23rd of last month, and covers all vehicles equipped with high-voltage batteries produced at a specific time at the plant in Nanjing in China. .
Previously, Hyundai Motor Company recalled 77,000 units manufactured from September 2017 through March last year worldwide after a series of Kona electric vehicle fires in October last year. The recall proceeded by updating the BMS and immediately replacing the battery if signs of battery abnormality were found, such as excessive cell voltage drift or rapid temperature change.
The Korea Transportation Safety Authority’s Automobile Safety Research Institute confirmed for the first time that the image of the fire caused by the thermal leakage test inside the battery cell was similar to the actual image of the car fire. Kona electric vehicle. The Automobile Safety Research Institute conducted several experiments assuming one fire occurred inside the battery cell and another outside the cell. As a result of conducting a fire test by creating conditions where a fire can only occur within the actual cell, the fire pattern was similar to that of a Kona electric vehicle fire. Additionally, as a result of scrutiny of the faulty high-voltage batteries collected as a result of the recall, it was confirmed that a fire could occur due to misalignment within the cell. The negative (-) tab kinks, which accumulates lithium byproducts on the negative electrode and spreads to the positive electrode, causing a short (short) in contact with the positive electrode tab.
The Ministry of Land, Infrastructure and Transport confirmed that the fire occurred in the battery cell on the left side of Pack 3 as a result of an interim investigation of a fire engine in Daegu on 23rd last month. Out of a total of 11 Kona electric vehicle fires in Korea, the Daegu fire case was expected to be an important clue as to the cause of the fire, as the battery damage was relatively minor.
Regarding the results of the investigation of the Ministry of Land, Infrastructure and Transport, LG Energy Solutions argues that it is difficult to see the failure of the battery cell as a direct cause of fire. This is because the BMS load map logic was confirmed to be incorrectly applied when the Kona EV BMS, which was under free repair since March last year, was updated. At that time, during the BMS upgrade process, there was a part that sped up the charging speed during fast charging, and this likely sped up the precipitation of lithium by-products. In this regard, the Ministry of Land, Infrastructure and Transport explained that as a result of the disassembly of the batteries of four Kona electric vehicles, it is difficult to determine a significant difference between the incorrect application of the logic of the load map and the normal application, and furthermore research is necessary. The Ministry of Land, Infrastructure and Transport also confirmed the damage to the battery cell separator, which was suggested as the cause at the time of the recall in October last year, and the fire reproducibility test is in progress, but not has been shown. through the experiment so far.
The Ministry of Land, Infrastructure and Transport reported that Hyundai Motor Company and LG Energy Solutions have not completed the investigation of defects by the Automobile Safety Research Institute, but have decided to replace the existing high-voltage battery system (BSA). with improved products to protect consumers. . The Ministry of Lands, Infrastructure and Transport plans to continue investigating defects that have not been completed, such as the fire reproducibility tests currently underway, to investigate the adequacy of this recall and supplement it if necessary.
Reporter Park Jung-min
