The Fire in the Brt Depot

The fire in the Brt depot in Bovisa has brought back to the forefront an issue known to those working in electric mobility: when a lithium battery enters thermal runaway, stopping it becomes complicated. In the Milan case, two containers full of electric bicycles continued to burn even after the warehouse was extinguished, and firefighters required extensive cooling work.

The fire erupted on the evening of July 8 at the Brt depot on Via Don Minzoni, in the Bovisa area, inside a warehouse used for package sorting, with various vehicles present in the yard. The flames also affected some administrative offices, while Arpa Lombardia initiated air quality assessments and the municipality issued initial warnings to residents within a 2-kilometer radius: keep windows closed, no outdoor activities, halt gardening and balcony vegetables, and avoid parks, nurseries, and kindergartens with outdoor spaces.

The dynamics, reconstructed by Corriere, stem from the very structure of lithium-ion cells: two electrodes separated by a thin diaphragm, immersed in a flammable electrolyte. If the separator is damaged due to impact, defect, or overheating, an internal short circuit occurs that generates further heat and can involve nearby cells in a chain reaction.

Why It's Difficult to Extinguish

The critical point is between 150 and 200 degrees Celsius, a threshold beyond which the electrolyte decomposes and releases flammable gases. In this context, water can cool the surface, but it does not always reach the core of the reaction, which is why in the Bovisa case there was a focus on continuous cooling rather than immediate extinguishing.

Corriere also notes the possibility of rekindling after hours or days, an aspect that necessitates prolonged monitoring of the vehicles or containers involved. Furthermore, the situation becomes even more concerning when the cells are packed in a closed volume, as heat and gases accumulate more easily, causing faster propagation between battery packs.

The fire in the Brt depot in Bovisa, therefore, reignites attention on a precise technical point: a lithium battery, once it enters thermal runaway, is very difficult to bring back under control. Inside a lithium-ion cell, there are two electrodes separated by a porous membrane and immersed in a flammable electrolyte. If the separator fails due to impact, defect, or excessive temperature, an internal short circuit occurs that generates further heat and can trigger propagation from cell to cell.

The crux of the matter is this: this is not a conventional fire. That is why cases involving electric bicycles and scooters often end up under prolonged observation, especially when exhausted batteries, questionable components, or non-certified installations come into play. The issue is not just the fire itself, but the difficulty in limiting a reaction that can restart when it seems to be under control.