Mystery of Mercedes EV explosion’s cause sparks fear of similar ignitions

The owner of the car said he had not used the vehicle for three days, debunking hypotheses that the cause of the explosion was overcharging.

A resident of an apartment complex in Incheon that suffered a massive fire from an EV explosion in an underground parking lot takes water from a water truck on Monday. Around 480 households have been suffering from electricity and water outages in the aftermath of the fire. [YONHAP]

Fears of EV explosions are mounting in Korea after it turned out that the Mercedes EV explosion in an underground parking lot in Incheon occurred while the car was not charging and had not been used for nearly three days.

According to local media reports on Monday, the car owner in his 40s parked the Mercedes EQE sedan at around 7:16 p.m. on July 29 and had not used it since then.

No single external stimulation occurred while the vehicle was parked, according to reports.

CCTV footage shows a Mercedes-Benz EV exploding in an underground parking lot in Incheon Thursday morning. [YONHAP]

The vehicle blaze broke out at 6:15 a.m. on Aug. 1 after the car was seen in CCTV footage exploding a few seconds after emitting smoke. The fire was fully extinguished after eight hours but sent a total of 23 people to nearby hospitals, including a firefighter and seven children.

The owner said he "hasn't used the car since the afternoon of July 29 ," according to reports.

The result seemingly debunks all earlier hypotheses that the explosion was caused by EV overcharging, which refers to charging beyond the maximum recommended capacity — normally 80 percent for today's EVs.

Firefighters inspect an underground parking lot in Incheon where a Mercedes EV caused a fire after exploding last week. A total of 140 cars were damaged, 40 of which were completely burned. [YONHAP]

Numerous scenarios for the cause of the blaze have been proposed, including flaws in the car itself and the batteries installed in the EV.

The burnt EQE is confirmed to have been equipped with high-performing, nickel-cobalt-manganese (NCM) batteries produced by China's Farasis Energy. NCM batteries with high nickel content are considered premium, with high energy density and a longer range per single charge, but carry a higher fire risk.

Lithium-ion batteries have cathode materials, anode materials and separators that keep the two electrodes apart from each other. Anode materials store lithium ions released by the cathode and create an electrical current that can be used to power vehicles.

If the separators are damaged, the cathodes and anodes may come into contact and catch fire.

The police and the National Forensic Service launched a joint investigation into the EV on Monday, three days ahead of schedule, in consideration of the difficulties the apartment complex's residents have been suffering.

The fire caused a power failure in the complex, affecting 480 households that lost electricity and water for five days straight. Around 300 people have been transferred to six state-run residential facilities.

A total of 140 vehicles were damaged, 40 of which were entirely burned.

“We are taking this very seriously and will do our best to collaborate with fire authorities to investigate the EV and determine the exact cause," said a spokesperson for Mercedes-Benz Korea.

BY SARAH CHEA [chea.sarah@joongang.co.kr]