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Giles Sedgman | Praxis

Lithium-Ion batteries on board yachts: A green solution or a red problem?

The superyacht industry is not alone in being affected by fires suspected to be caused by the malfunction of Lithium-Ion batteries. Giles Sedgman looks at the safety aspects of these batteries on board.


Lithium-ion (Li-ion) batteries are rapidly becoming the power source of choice due to their relative high storage capacity in relation to their size and rapid recharging capability. The technology has been especially embraced in the tenders and toys sector. On smaller yachts, petrol storage concerns may have previously prevented an owner purchasing that must-have toy, however when all you need is a charging cable and a nearby power socket there is no reason not to squeeze a jet ski or underwater scooter into the final few square feet available in their garage space or lazarette. Even on larger yachts the petrol and diesel driven toys are increasingly disappearing, if not for ‘green’ reasons, then for the sheer convenience of electric.


What exactly is the problem with Li-ion batteries?

The problem is mostly centred around a phenomenon called ‘thermal runaway’ which is an uncontainable, exothermic reaction that can occur inside a Li-ion battery when it gets damaged or short-circuited.

When the rechargeable Li-ion battery’s cathode (+) and anode (-) make contact due to damage to the internal barrier that separates them, a short circuit occurs, which results in the materials inside the cell starting to decompose. These decomposition reactions generate relatively large amounts of heat, which is why the battery temperature quickly rises to the melting point of the metallic lithium, causing a violent self-heating chain reaction.

During thermal runaway, the battery can heat up to over 600°C in a matter of seconds, rising to over 1,000°C as the runaway develops. The decomposition results in the formation of simpler, more flammable substances, such as methane, ethane, and hydrogen gas. In addition, the cathode also starts to decompose and releases oxygen. All this results in a pressure and temperature build up inside the battery, and eventually, an explosion.

The ensuing fire is very difficult to extinguish, while behaving like a metal fire (rapid generation of very high heat levels, easy to flare up) using a Class D (metal) fire extinguisher will not actually be effective. This is because the lithium inside the Li-ion battery occurs as a salt not as a metal, therefore currently classified as a Class B (flammable liquid) fire. The fire safety industry experts, recognising that swift and proper extinction preventing flare-up remains a difficult proposition, have responded by bringing to market AVD extinguishers specifically designed to tackle Li-ion battery fires. The Lithium also produces toxic fumes, so anyone attending needs to be in full SCBA sets. This further complicates the issue of tackling a fire.

However, prevention is always better than cure and the UK-MCA’s 2016 Marine Guidance Note: Electrical Installations – Guidance for Safe Design, Installation and Operation of Lithium-ion Batteries have been incorporated into the 2019 REG Large (Commercial) Yacht Code (Common Annex A) and gives guidance on risk-assessing, maintenance and safety management procedures, while detailed installation guidance considers aspects such as location/fire rating of boundaries, ventilation, electrical power, fire detection and suppression, gas detection, drainage, ambient temperature control, and the presence of a fit for purpose battery management system.

The guidance is primarily addressed to all shipowners, ship operators, masters and officers of ships, ship designers and shipbuilders, but it makes for useful reading material for any yacht owners considering a retrofit, providing an insight into the many aspects to consider. Sarnia Yachts are happy to discuss specific yacht requirements.”

Not all the increasing number of plug-in-based gadgets available are necessarily meeting or even cognisant of the requirements of a commercial yacht code, set of classification rules or EN standards, meaning that the insurer has to allow for a relatively large set of unknowns.

On board most yachts, tenders and toys have always lived in the garage or lazarette. Given that the garage space of a Code-compliant yacht will meet many of the requirements listed in the aforementioned guidance, just some minor modification or additional equipment to make the storage and handling of batteries a reasonably safe proposition could be all that’s required.

But what about the many yachts, that are not constructed to Code, or yacht hulls not constructed in steel? Understandably, the desire to incorporate the use of battery powered implements is quite apparent on there too. It will not be straightforward to find an existing space or to remodel the yacht to create a space that will be suitable. On those yachts, the solution may be to keep battery powered tenders and toys stowed on the exterior decks or separate the battery pack from its appliance when not in use, or as a minimum, confine the battery charging process to somewhere outside of the vessel’s structure.

What all the above highlights is that, consequently, the risks associated with the new technology have potentially altered the risk profile yachts are exposed to.

We can help yacht captains and owners to review their yacht’s insurance policies so they can seek the appropriate advice from their insurance brokers if they’re thinking of retrofitting or equipping their yacht with lithium-ion powered implements, toy-like or otherwise. This is especially important for winterised vessels.

While Praxis Yachts is not a regulated provider of insurance services and unable to provide specific advice, with insurance providers becoming increasingly wary of underwriting Li-ion powered installations we are able to assist with helping clients access specialist marine insurance providers.

Li-ion batteries are here to stay, that much is certain.

It is up to all yacht industry stakeholders collectively to come up with safe and acceptable ways of incorporating these batteries into the future operation of yachts new and existing alike, in all their splendid variety.

While early conversations with the yacht’s insurance provider and with the Flag Administration may prove useful it goes without saying that a good yacht manager can play a valuable role in these conversations as well.

For advice and guidance please contact Giles.


Please note that this article is intended to provide a general overview of the matters to which it relates. It is not intended as professional advice and should not be relied upon as such. Any engagement in respect of our professional services is subject to our standard terms and conditions of business and the provision of all necessary due diligence. © Praxis 2023