Lithium-ion Batteries: Fire Risks and Loss Prevention in Yachting (part II)
We saw in the first part how Lithium-ion batteries function, what are their hazards? The consequences if things go wrong and the causes of these hazards. Now we will speak about prevention and fire suppression. Prevention is of paramount importance since once a fire has started it is almost impossible to eradicate due to mainly the following reasons:
– In most of the fire cases a thermal runaway starts which is a self-sustainable, batteries will continue to burn without access to additional oxygen;
– The battery cell temperature rises incredibly fast (milliseconds) triggering a chain reaction which in turn creates extremely high temperatures (around 400 degrees Celsius), needless to say that a fire of this magnitude on a Yacht made out of GRP is a deadly combination and is very difficult to extinguish.
– frequent reignition a while after a fire has been suppressed, once the fire is contained it is yet over.
– the hazardous gases produced during Lithium batteries fire.
All of the above means that crew awareness on Lithium batteries hazards is crucial and the crew should detect early signs of batteries problems before they become a hazard for the yacht.
It is worth mentioning too that preventions equipment and planification is better be considered at an early stage of design and construction (****), however if not possible it is possible to consider them during the life of existing vessels. On this subject we would like to make a disappointing disclaimer, it will take too long to discuss the optimal design and construction in terms of fire prevention, and it will be too technical for us.
4) Loss Prevention Guidance
a) In case of physical damages to the batteries, disembark them!
As we saw in the M/Y Kanga fire and as per the Marine Safety Investigation Unit of Transport Malta the fire started while none of the three damaged batteries were being recharged. Then don’t leave it to luck when a lithium-ion battery is damaged disembark it, at the first opportunity! This is even truer when the risk of saline penetration is high. Needless to say, that damaged batteries should not be charged;
b) State of Charge (SOC)
Lithium batteries stability is affected when completely discharged or overcharged. Avoid fully charged or completely discharged batteries, during transportation or long storage, the ideal SOC (it refers to how much charge is left in the battery) would be between 30% to 50%, this is of course depending on manufacturer’s recommendation, the expected time in storage before being used, the battery size/type and its ultimate usage. Then charge them before they are drained out and stop charging them before they are completely charged (a rule of 20%/80% except for long term storage would be suitable).
A safe recommendation is to follow religiously manufacturer’s instructions;
c) Avoid thermal abuse (high or low temperatures), keep them under a shade!
During storage avoid temperatures below 0°C and for most batteries the recommended storage temperature is around 15°C subject of course to the confirmation of the manufacturer as per its instructions. Avoid direct exposures from sunlight or adjacent heat sources. Let the batteries cool before charging them and don’t let it overcharge it will heat;
d) Train the crew in particular to follow MGN 681 (M) guidelines for fire safety and storage of small electric powered craft on yachts (www.gov.uk), this will increase too their understanding of the fire risks from Li-ion batteries. Crew should be trained for early detection of battery problems before it becomes a serious concern to the safety onboard and to use of any equipment such as Li-ion specific fire extinguishers, fire blankets, IR cameras, PPE for handling spilled electrolytes etc.
All batteries over 100 Wh for use with electric vehicles should be subject to the storage requirements as per MGN (****).
Few examples: a typical laptop computer has an energy of 40 Wh, a mobile phone around 10 Wh, electric tenders 40-100 kWh, Electric Jet Skis 20-50 kWh etc.
e) Store them in a dry place, as far away as possible from petrol driven craft or petrol tanks and when not in use in a fireproof battery box;
and away from flammables or corrosive substances;
f) Avoid storing Lithium batteries together.
To do so will not increase the risk of fire but if one battery catches fire it will spread to the others;
g) Consider the installation of a gas detection method targeting CO2 concentration;
h) Make sure that charging is always attended, done during the day, on deck only, in a space free of sources of ignition or flammable materials and as per manufacturer’s recommendations. Your yacht should be equipped with an automatic device to stop the battery charging in case of a detection of fire or high temperatures;
i) To make sure that a Battery Manage Systems (BMS) is installed. A BMS monitors the total battery current/voltage, the temperature in battery modules, individual cell voltage, battery current. In case of a deviation from a suited charged temperature range (15 °C and 35°C) the BMS will trigger countermeasures going from de-activating the faulty cell (s) to disconnecting entire battery from the electrical system.
j) The right choice of battery: The LiFePO4 (Lithium Iron Phosphate) battery, also called the LFP battery, is a type of rechargeable battery, it is the safest Lithium type of battery, some insurers started to impose this types of batteries.
5) Fire suppression (****)
a) Fire detection and alarm
To fight a fire we need to know that it started, it is why early detection is of paramount importance. A system in place should be able to provide an early warning that there is a hefty increase in temperature, or identify the start of a fire, a thermal runaway or a battery off-gassing. Infrared red cameras which detect thermal energy and then convert it into an electrical signal (or another thermal imaging system) and then trigger an alarm are recommended. Increase in battery temperature is common while charging but one should be started concerned of a runway between 60 °C and 70 °C.
b) Fire suppression
A quick response is needed to suppress the fire with an abundant amount of water over a long period. Task won’t be easy, a large electric car (60 kWh to 80 kWh similar in battery capacity to a larger electric tender) may need around 10,0000 liters of water to be extinguished since once thermals run away (the heat generated from within exceeds the amount of dissipated heat) has begun, the battery fire will rapidly increase in intensity and makes it extremely tough to eradicate. Battery compartments should be protected by an appropriate automatic water-based fixed fire-fighting system, water-mist systems have been proved to be the most efficient in fighting battery fire. Portable fire-extinguishers located outside the battery compartment, blankets, PPE etc. are a must.
Yacht insurers have started to systematically insert subjectivities related to Lithium-ion batteries in their insurance policies, in case of fire Yacht owners and crews will have to adhere to certain safety guidelines and Lithium batteries will have to be of a certain type to have the fire claim covered.
You have worked in your life to buy this yacht, don’t let an apparently innocuous equipment on board or unsound charging practices ruin in no time the dream of your life which became true. Before getting even to prevention, invest in the hiring and training the captain/crew, quality people are always costly at the beginning never at the end.
References
– Lithium batteries whitepaper – Brookes Bell – TT Club – UK P & I club – managed by Thomas Miller (*)
– Lithium-ion batterie risk bulletin – Allianz GC & S – August 2022 (**)
– https://www.transport.gov.mt/16_2019.pdf-f7994 (gov.mt) Marine Safety Investigation Unit of Transport Malta (***)
– MGN 681 (M) fire safety and storage of small electric powered craft on yachts (www.gov.uk) (****)
– Kanga fire report: How safe are Li-ion batteries aboard yachts? (superyachttimes.com)
– https://www.saurenergy.com/solar-energy-blog/why-do-lithium-ion-batteries-catch-fire-how-to-avoid-the-mishap
– https://ft.pressreader.com/v99c/20231028/281689734501963
– Shipowners urged to protect vessels against electric-car fires (ft.com)
