Your vessel is carrying electric vehicles. Your fire system was not built for them.
An EV fire on a ship is not a bigger version of a petrol-car fire. It is a chemical process that makes its own oxygen, can reignite for days, and cannot be stopped by the agents most vessels carry. This is the plain-English explanation of what actually happens, what the independent evidence says, and what closes the gap conventional firefighting leaves open.
What thermal runaway actually is
A lithium-ion battery stores energy in cells separated by a thin membrane. If a cell is abused — by heat, mechanical damage, overcharge, or a manufacturing fault — that separator can collapse, the electrodes touch, and an internal short circuit dumps heat into the cell. The heat tips neighbouring cells over the same edge, and the reaction becomes self-sustaining: heat releases energy, energy releases more heat, cell to cell, through the pack. That cascade is thermal runaway.
The decisive point for firefighting is that the cathode material generates its own oxygen. A petrol fire needs air; starve it of oxygen and it dies. A battery in thermal runaway does not, which is why conventional oxygen-depriving tactics do not interrupt it.
Reignition: the fire that comes back
The particular danger of EVs is reignition. A battery that looks extinguished can relight for an extended period — up to 72 hours by widely cited figures — because pockets of damaged cells can tip back into runaway long after the visible flame is gone. At sea, that turns a “controlled” fire into an open-ended liability: every hour the vessel is underway after apparent suppression is an hour the question “is it actually out?” remains unanswered.
It is also why cooling and containment, not just extinguishment, define a good EV response. The only reliable way to take reignition off the table is to bring the battery's temperature — and its state of charge — down and keep them there. Submerging the pack in water does exactly that.
Toxic and explosive gas
Thermal runaway vents hydrogen fluoride and other toxic gases, and the vent gas is typically around 30% hydrogen with carbon monoxide sometimes up to 60% by volume. If those gases do not ignite immediately, they can accumulate into an explosive atmosphere in an enclosed deck — which is why managing the gas, not only the flame, is part of any competent strategy.
CO2, foam, mist, drencher — all manage, none neutralise
Full-scale testing, including the EU's LASH FIRE project, shows that water-based drencher systems can manage and control an EV fire as effectively as an ICE-vehicle fire. That is genuinely useful — but the same research is clear that no fixed system stops thermal runaway:
CO2 and foam deprive the fire of external oxygen, which a self-oxygenating battery does not need. High-expansion foam can hinder gas ignition while a vehicle stays submerged, but gases keep forming and the system cannot end the runaway. Water mist and drencher systems cool well and protect boundaries, but they too cannot reduce or prevent thermal runaway. On a car carrier there is the added problem that water across the deck reduces tyre friction and threatens stability.
So conventional suppression gets you to “flame knocked down” — and then stops short of “battery neutralised.” That gap, between suppression and resolution, is the entire problem EV containment exists to solve.
Why fire blankets are the wrong tool for EVs
Fire blankets are increasingly bought as an “EV measure,” but the leading fire authorities warn against them for electric vehicles. DBI, the Fire Research Safety Institute (FRSI) and the NFPA have all flagged the same risk: a sealed blanket can trap the explosive gas a battery vents, allowing it to concentrate and ignite underneath.
A blanket also does nothing about the battery itself — it hides the flame without cooling the cells, so the reignition clock keeps running. An effective containment system instead vents gas upward and submerges the battery.
What has already happened at sea
Several recent total-loss and near-loss incidents involved vehicle carriers with EVs aboard. The pattern is the same each time: once a fire reaches EV cargo, conventional suppression does not end it.
Felicity Ace
A car carrier with roughly 3,965 vehicles caught fire and sank after burning for days. Estimated loss around $450 million. No conventional system stopped the spread.
Fremantle Highway
A car carrier with thousands of vehicles, including EVs, burned for days off the Dutch coast — one crew fatality and a major salvage operation.
Morning Midas
A car carrier with around 800 EVs among 3,000 vehicles caught fire roughly 500 km from shore; 22 crew evacuated with no land-based support available.
Three criteria any maritime EV response has to meet
These are not product specifications. They are the operational conditions that determine whether any response — system, procedure or equipment — can actually work when deployed on a vehicle deck.
It must work in the space that actually exists
Standard vehicle-deck clearance is 20–40 cm between vehicles. Any approach that needs open space is not deployable in the conditions where the fire is most likely to occur. The response has to work in the actual space available, not the ideal space.
It must neutralise the battery, not just the flame
Suppression is not neutralisation. For reignition risk to be eliminated, the pack must be physically cooled below the thermal-runaway threshold and then kept there. Visible flame suppression alone does not achieve it.
It must be deployable by the crew who are aboard
When a vessel is 500 km from the nearest port, the people available are the crew. Two standard crew members without specialist fire-brigade training, inside the window before thermal cascade — that is the deployment reality any response has to be designed for.
The regulatory picture is moving — but not finished
The IMO's Sub-Committee on Ship Systems and Equipment (SSE) is reviewing fire protection for vehicle and ro-ro spaces carrying new-energy vehicles. Amendments to SOLAS and the Fire Safety Systems (FSS) Code — mainly for new passenger ships — point toward fixed fire detection, video monitoring and fixed water-based systems on weather decks. But STCW does not yet address EV carriage, and there is no agreed limit on the state of charge of EVs shipped as cargo.
In the meantime, flag states have no requirement for EV-specific equipment, and class-society notations are emerging as a way to evidence good risk management. The practical takeaway from IUMI is that operators are expected to proactively explore improved firefighting capability — and to be able to show they considered the post-suppression phase. Carrying an independently tested containment system, with the test report and crew training on file, is a direct way to demonstrate that.
The same fire, three different problems
An EV fire behaves the same chemically wherever it happens. What changes is what it costs you — and what you can physically do about it.
A passenger-safety and schedule problem
People and vehicles share the deck and there is nowhere to divert to. You cannot let passengers drive vehicles off, or release the next sailing, while a battery on the deck may still relight.
EV fire on ferries & Ro-Pax →A stability and total-loss problem
Thousands of vehicles as little as 10 cm apart on large undivided decks. Hosing the deck reduces tyre friction and can shift cargo — so the usual containment tactic is itself a hazard.
EV fire on car carriers →An access problem
Commercial EVs, electric trucks and heavy plant in enclosed tunnels and lower decks, where physical access is difficult and fixed systems often cannot reach the battery pack itself. The response has to go wherever the crew can go.
Covered on the EV-X system pageClose the gap: contain the battery, not just the flame
EVstinguish EV-X is the step conventional suppression cannot provide. After the fire is knocked down, two crew wrap the vehicle and flood a patent-pending barrier until the battery is submerged — eliminating reignition with the water contained, not spread across the deck. It is independently fire-tested by DBI and needs no class or flag-state approval to carry.
EV fires at sea — FAQ
Questions about the EV-X system itself — deployment, specifications, class approval — are answered on the EV-X product page.
Can an EV fire be extinguished like a normal car fire?
How long can an EV battery reignite after a fire?
Are EV fires hotter or more intense than petrol-car fires?
Why not just use a fire blanket?
Is there a regulation requiring EV-specific equipment today?
Talk to an EV fire safety specialist
Whether you operate ferries, car carriers or mixed ro-ro, we can assess where the reignition gap sits in
your current fire plan — a due-diligence conversation, not a sales pitch. You can also request the full
DBI full-scale fire test report and video.
Prefer to talk? Email tech@sepcotech.com
· +45 6916 2400
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Related reading
EV fire on passenger ferries
Why reignition — not the flame — is the threat to passengers and schedules.
EV fire on car carriers
Density, stability and the cargo-shift risk that makes open hosing dangerous.
Sources: IUMI, Risk mitigation for the safe ocean and short sea carriage of electric vehicles (September 2025); DBI (Danish Institute of Fire and Security Technology) full-scale EV-X fire test, report SIXC25005 (November 2025); NFPA Research Foundation, Modern vehicle hazards in parking structures and vehicle carriers; EU LASH FIRE project; Australian Maritime Safety Authority guidance. Figures are summarised for general guidance and are not a substitute for a vessel-specific risk assessment.