Kim Pil-su, President of the Electric Vehicle Association, "Lower Charging Amounts Are Safer... Full Battery Inspection Needed"

Professor Kim Pil-su from the Department of Automotive Engineering at Daelim University is attending the '2023 Korea Green Mobility Awards Ceremony' held at the Press Center in Jung-gu, Seoul, on January 31, 2023, and delivering a judging comment. Photo by Kang Jin-hyung aymsdream@

Kim Pil-su, President of the Korea Electric Vehicle Association (Professor of Automotive Engineering at Daelim University), claimed that the lower the electric vehicle (EV) charging rate, the safer it is from fire hazards. This contrasts with Hyundai Motor Company's assertion on the 20th that there is no correlation between EV charging levels and fire incidents. Accepting the opinions of Professor Kim and other experts, the Seoul Metropolitan Government announced a policy to limit the charging rate to 90% or less in underground parking lots of apartments and other buildings.

In a phone interview with Asia Economy on the 21st, Professor Kim emphasized, "Although manufacturers provide a safety margin (extra capacity) in EV batteries, it has been proven through various experiences that the lower the charging level, the safer it is from fire risks."

Professor Kim added, "Even if manufacturers set safety margins in batteries and strengthen the Battery Management System (BMS), the possibility of fire remains. Reducing the charging level helps prevent fires." Lowering the charging level reduces the amount of energy stored in the battery, thereby maintaining a more stable state.

In fact, in the past, when fires occurred in Energy Storage Systems (ESS) or electric vehicles, the government, battery manufacturers, and automakers included charging rate restrictions as a key countermeasure. After a series of fires in ESS in 2019, the Ministry of Trade, Industry and Energy implemented measures to limit charging rates to 80% indoors and 90% outdoors. Overseas ESS sites are also known to maintain charging rates below 80%. When fires broke out in the U.S. GM Bolt and Hyundai Kona EV, automakers conducted recalls to reduce the charging level to below 90%.

Professor Kim explained, "Internationally, when exporting electric vehicles, the charging level is limited to 30%." The Ministry of Oceans and Fisheries also recommended on the 8th that the charging rate be limited to 50% when loading electric vehicles onto ships.

Professor Kim also emphasized the need for battery and automaker manufacturers to conduct full inspections of batteries before shipment. He said, "Most of the electric vehicles currently experiencing fires are new models that have been released recently. A full inspection to filter out defective battery cells before shipment is necessary."

Hyundai Motor Company and Kia explained in reference materials distributed to the media on the 20th that batteries for electric vehicles are designed to be safe even when charged to 100%. Even if drivers charge to 100% numerically, there is actually a safety margin reserved. Hyundai and Kia are known to apply a safety margin of about 97-98%.

The nickel-cobalt-manganese (NCM) batteries most commonly used in domestic electric vehicles can store up to 275 milliampere-hours (mAh) per gram, but battery manufacturers set the usable capacity lower at 200-210 mAh per gram. Automakers also reserve some usable capacity and display the charging level as 100%.

Hyundai and Kia explained that physical short circuits or shorts occurring inside the battery have more impact on battery fires than the charging level itself.

This content was produced with the assistance of AI translation services.