On June 8, almost two months after a Zotye M300 (Langyue) EV caught fire which prompted the city of Hangzhou to pull all 30 electric taxicabs off the streets (see our post here), the investigation team from the Quality Supervision and Inspection Administration of the city and Zhejiang province, announced their findings at a press conference, tracing the cause of the fire to the car’s defective battery pack.
As taxicab, a Zotye M300 EV is propelled by the power from the battery pack installed in the trunk, which comprises several stacks of lithium-ion battery cells. The stacks are removable, and switched with fresh ones when depleted.
"In sealing and packing the battery cells, in loading and unloading the battery stacks, insufficient attention had been paid to several safety factors; monitoring procedures had been inefficient or neglected in the process of manufacturing, battery charging/switching, and vehicle driving, failing to detect anomalies," said Shao Xinhua, deputy administrator of the Hangzhou Quality Supervision and Inspection Administration.
According to the investigation report, the battery pack problems occurred on the M300 EV in question include: leaking of battery cells; damage of the insulation between battery cells and the walls of the aluminum container in which the cells were stacked; short circuits occurred within certain containers and those involving supporting and connecting parts. One of the stronger short circuits ignited the car’s back seats.
The report adds that the battery cells on the car, made by Zhejiang Wanxiang Group, themselves were not responsible for the accident, but were employed improperly for an electric taxicab.
In the past two months or so, all the remaining 29 electric taxicabs in Hangzhou had gone through thorough inspection, and certain modifications had been made, including installing re-designed battery packs. With new and improved safety procedures in place, the investigation team said the EV fleet could now return to the streets.