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Lithium-ion battery safety on boats

Electric tenders, jet skis and other personal watercraft powered by Li-ion batteries have emerged in recent years as alternatives to petrol-powered craft.

However, there have been calls nationally for greater awareness on their safe use following an increase in the number of fires on yachts.

Industry groups reported 16 total losses due to fire between August 2021 and August 2022, only half of which have a known cause.

The UK Government has issued a Marine Guidance Note (MGN) specifically on the use of Li-ion batteries, which contains important advice on fire prevention, safe storage and early detection of any issues.

Guernsey Ports assistant harbourmaster Kieran Higgs said these batteries need to be treated differently to other power sources.

"Understanding the correct safety procedures is important as the consequences of a battery fire can be catastrophic," he said.

"Thermal runaway is the cause of most lithium-ion battery fires. This is where the battery continues heating until it catches fire. With the mixture of gases released, fires can intensify rapidly and become extremely difficult to extinguish.

"The risk is greatly increased when a battery is damaged or it hasn't been stored or charged safely.

"That is why it's so important to understand the risks and mitigate them by following appropriate safety procedures and training all crew members on early detection of the warning signs."

One of the most effective preventative measures is to fit the right equipment to begin with.

Li-ion batteries, associated systems and chargers should only be sourced from reputable manufacturers and retailers, and they should have appropriate certification.

All batteries should be stored, charged, and operated in accordance with the manufacturer's instructions.

Storage compartments should not be allowed to rise above 45 °C, as thermal runaway can begin at anywhere between 60 °C and 70 °C.

These compartments can be fitted with cooling systems, fire suppressants and monitoring systems which contain fixed smoke, heat and gas detectors. Where possible, alerts should be interfaced with the vessel's safety management system.

While all crew should be trained in safe use of Li-ion batteries, it is recommended that a named person on-board is appointed chief responsibility for the safe operation, maintenance and response to emergencies involving Li-ion batteries, due to the unique challenges they pose.

The full Marine Guidance Note on Li-ion batteries can be found here: MGN 681 (M) fire safety and storage of small electric powered craft on yachts - GOV.UK (