Why battery type approval requirements must remain stringent

Operators were told they must be wary of how many connections they manage and be aware that larger capacity cells bring more problems. Vessel managers should define the cooling capability required, factoring in system aging and the size of the system needed to operate safely.

When designing a battery and opting for an air-cooled, rather than a liquid-cooled system, Sterling PlanB CEO Brent Perry said the system should be oversized in order to keep up with the heat being generated as systems evolve.

“You have to give yourself something to last ten years” he said. Many batteries are manufactured with live terminals, so measures should be put in place to mitigate the risk to crew safety.

Mr Perry said battery owners must ensure adequate fire-fighting equipment, including from third parties if needed, but advised caution.

“You have to make sure that the third party system completely understands the risk of managing not only the initial fire-fighting of the system but the long term risk of lithium fires which can go on for days,” he said.

For its systems, Sterling PlanB attaches a voltage and temperature sensor to each cell to manage charge and discharge of a cell and performance as the cells age.

Norwegian Maritime Authority (NMA) surveyor for passenger vessles, Arne Brathole said the NMA uses guidelines instead of regulations because the former are a faster to publish, quicker to update and overall more efficient way to make technology and best practices available. NMA’s safety guidelines on lithium-ion batteries are configured such that thermal runway and mechanical damage to battery systems are covered as a potential outcome, with mitigation measures included.

NMA has experience with such hazards, Mr Brathole said. In 2019, fire damage took place in the battery room of Roro ferry Ytterøyningen when a fire that originated outside the battery’s cells caused an explosion and resulted in structural damage to the vessel. In light of the incident, several class regulations have been updated to reflect the demand for independent gas detectors, fixed fire extinguishers, increased requirements for ventilation and other equipment requirements.

Mr Brathole said the incident exposed a lack of knowledge in emergency procedures and training which the NMA is now seeking to rectify. He added that industry stakeholders should be willing to share information with flag societies, class and fire departments. Going forward, NMA is revising its guidelines and working with owners to put in place satisfactory training for crews.

Since safety considerations differ for fully electric and hybrid vessels, this impacts how battery management and alarm systems are programmed. Because hybrid systems are not totally dependant on energy storage for propulsion. Mr Perry said “typically, we would design the go/no-go safety rules in the battery management system specific to the idea that we would protect the battery in case there was a problem within the system and not necessarily put the ship at risk”.

“In an electric system, the safety of the vessel is going to be much more dependent on the ability of the ship to move and manage its energy. There, we would sacrifice the battery in terms of having it work beyond expectations if it meant the safe docking and safe operation of the vessel.”

Panellists agreed that the class rules are clear, comprehensive and always improving. Jon Diller, director of sales & marketing at Spear Power Systems noted that each class society has a separate set of standards, meaning battery manufacturers must comply with and incorporate every possible standard into their designs.

“They have done a phenomenal job of understanding the risks of lithium-ion batteries,” he said.

Corvus Energy CCO Halvard Hauso said his company is in favour of stricter rules on type approval.

“We think it should be much more difficult to get type approval. We think the requirement should be to have a single cell thermal runway protection in your ship. Then, you will take away industrial batteries being put on board a ship.”

Solid state battery cell technology – which can control the risk of thermal runaway – is still nascent in terms of commercial usage, and Mr Hauso said operational safety practices with regard to thermal runaway are currently “a matter of controlling risk and mitigating it”.

Mr Diller also cautioned against the dangers of putting profit over safety, saying “we need to be on guard against acceptance of second-tier levels of safety from battery suppliers in an attempt to push costs down”.