The Tokyo Fire Department reported 43 lithium-ion battery fires in July, marking a record high for the month [1].
This surge highlights the growing safety risks associated with the widespread use of rechargeable batteries in consumer electronics during extreme heat. As temperatures rise, the likelihood of battery overheating increases, posing a significant threat to urban residential safety.
According to the Tokyo Fire Department, the number of fire incidents in 2026 has increased 1.5 times compared to the same period in 2025 [2]. The department said that the majority of these fires occur while the devices are charging [3].
Officials said the fires are not limited to mobile power banks. Other common sources of ignition include electric bicycles, electric shavers, and cordless vacuum cleaners [1]. These devices utilize lithium-ion technology that can become unstable under certain conditions.
Experts identified two primary causes for the outbreaks. Rising ambient temperatures increase the risk of thermal runaway, while internal defects during the manufacturing process or malfunctions during the charging cycle can trigger combustion [1].
To mitigate these risks, the department has emphasized the importance of using certified charging equipment and avoiding the overcharging of devices. They said that keeping batteries away from direct sunlight, and ensuring proper ventilation during charging, can reduce the risk of overheating [1].
“43 lithium-ion battery fires in July, marking a record high for the month”
The correlation between peak summer temperatures and battery failures suggests that current consumer-grade thermal management systems may be insufficient for intensifying heatwaves. As Tokyo integrates more micro-mobility options like electric bicycles, the risk profile for residential fires shifts from traditional electrical shorts to chemical combustion, requiring updated public safety guidelines and potentially stricter manufacturing standards for batteries sold in high-heat climates.
