According to a recent report, flooding from hurricanes Helene and Milton in the US in September and October 2024 caused dozens of electric vehicles and other battery-powered objects, such as scooters and golf carts, to catch fire.
- According to one tally, 11 electric cars and 48 lithium-ion batteries caught fire after exposure to salty floodwater from Helene. In some cases, these fires spread to homes.
Key points
- When a lithium-ion battery pack bursts into flames, it releases toxic fumes, burns violently and is extremely hard to put out. Frequently, firefighters’ only option is to let it burn out by itself.
- Particularly when these batteries are soaked in saltwater, they can become “ticking time bombs”. That’s because the fire doesn’t always occur immediately when the battery is flooded.
- The trigger for lithium-ion battery fires is a process called thermal runaway – a cascading sequence of heat-releasing reactions inside the battery cell.
- Under normal operating conditions, the probability of a lithium-ion cell going into thermal runaway is less than 1 in 10 million. But it increases sharply if the cell is subjected to electrical, thermal or mechanical stress, such as short-circuiting, overheating or puncture.
- Saltwater is a particular problem for batteries because salt dissolved in water is conductive, which means that electric current readily flows through it. Pure water is not very conductive, but the electrical conductivity of seawater can be more than a thousand-times higher than that of fresh water.
- All batteries have two terminals. One is marked positive (+), and the other is marked negative (-). When the terminals are connected to a device that uses electricity to do work, such as a light bulb, chemical reactions occur inside the battery that cause electrons to flow from the negative to the positive terminal.
- This creates an electric current and releases the energy stored in the battery.
- Even a battery pack that is fully discharged isn’t necessarily safe during flooding. A lithium-ion cell, even at 0% state of charge, still has about a three-volt potential difference between its positive and negative terminals, so some current can flow between them.
(Source: https://theconversation.com/saltwater-flooding-is-a-serious-fire-threat-for-evs-and-other-devices-with-lithium-ion-batteries-240770)
