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The Fire in the Box You Cannot See: Lithium-Ion Batteries and the Threat Below Deck

🕑 5 min read words News

Right Now, There Is Almost Certainly a Lithium-Ion Battery on Your Vessel

In a container in the hold. In a colleague’s phone in their cabin. In a laptop in the office. In an electric vehicle on the car deck. Most of the time, nothing happens. But when it does go wrong — it goes wrong fast, violently, and in ways that conventional firefighting cannot easily stop.

The CINS guidelines, now updated and endorsed by the International Group of P&I Clubs, make one thing very clear: existing regulations have not kept pace with the scale of this risk. That gap falls on you.

What Is Thermal Runaway?

Thermal runaway is not just a fire — it is a self-sustaining chain reaction. When a lithium-ion cell is damaged, overcharged, overheated, or has a manufacturing defect, its internal temperature begins to rise. That heat triggers chemical reactions that generate more heat. The cycle accelerates. The cell vents flammable, toxic gases. Then it ignites. Neighbouring cells pick up the heat and begin their own thermal runaway.

A single damaged battery in a container can cascade through thousands of cells. Conventional firefighting agents — CO2, foam, water mist — may not extinguish a thermal runaway fire. They can suppress visible flames, but the chemical reaction continues internally. The fire can reignite hours later.

The Scale of the Problem

Nordic marine insurers (Cefor) identified fires as one of the major sources of marine losses in 2025, highlighting a specific increase in severe fire incidents on container vessels and car/RoRo ships. Global lithium-ion battery demand surpassed 1 TWh in 2024 and is projected to reach approximately 4.7 TWh by 2030. That growth means a proportional growth in the volume of these cells being shipped at sea — including damaged, defective, and misdeclared units.

Misdeclaration of dangerous goods is a persistent problem. Shippers may intentionally or accidentally fail to declare lithium-ion content in consumer electronics, EV components, or industrial equipment. Crew have no way of knowing what is inside a sealed container — which is exactly why the procedures around stowage, monitoring, and emergency response matter so much.

What Crew Must Know

Know the Stowage Requirements

CINS guidelines specify that lithium-ion batteries should not be co-loaded with other dangerous goods. Packing requirements include a 30cm gap between cargo and the container ceiling, a 30cm gap between cargo and the container doors, and packaging that does not contact container walls directly. These gaps exist to allow firefighting access and to limit fire spread. These are not optional recommendations — they are the difference between a contained incident and a catastrophic one.

Recognise the Warning Signs

Early signs of a battery problem include unusual heat from a container, a sweet or acrid chemical smell (venting gases), discolouration of container surfaces, or smoke visible from vents. These may appear hours before open flame. Any such sign should be reported immediately and the Master informed. Do not open a container you suspect is experiencing a battery incident without proper PPE and a clear firefighting plan.

Understand Your Vessel’s Firefighting Limitations

Standard fixed firefighting systems are not designed for lithium-ion fires. Flooding with water to cool the affected container is currently the most effective suppression method for thermal runaway at sea. This requires large volumes of water and sustained application. Know your ship’s firefighting plan for cargo holds and car decks before you need it.

Personal Devices Matter Too

Every crew member carries lithium-ion batteries in their personal devices. Charging phones and laptops overnight, using unofficial chargers, charging in confined spaces — all of these increase risk. One cabin fire from an overcharging device can endanger everyone on board.

Critical Questions

Do you know where the lithium-ion battery consignments are stowed on your current voyage — and are they in the correct positions?
When did you last review your ship’s emergency plan specifically for a cargo fire involving dangerous goods?
Does your crew know that water — not CO2 — is the primary tool against thermal runaway, and why?
If you smelled something unusual coming from a hold right now, what are the first three steps you would take?
Have you personally checked the charging habits in the crew accommodation — unofficial chargers, overnight charging, charging in enclosed spaces?