negative with a metal object will either result in the battery terminals evaporating or the metal object getting very hot.


by Chris Kruger


A Li-ion battery has several potential hazards that must be considered in order to keep people and equipment safe. It is important to consider these hazards for each stage of the battery life, not just the day it is installed. From manufacturing through to delivery, installation, commissioning, maintenance and eventually the recycling of the battery, safety must be first and foremost.


At the core of the system is the lithium-ion cell; a chemical power plant that cannot be simply switched off in order to make it safe. A battery cell is by its nature always live; therefore, it is important to ensure the safety of personnel from this potential hazard. The voltage on a single cell is low and therefore not hazardous, however the potential current is very high since the internal resistance of the cell is low. Shorting the positive and


During manufacturing, special tooling and processes are used to decrease the risk of short circuit of a cell. When the cells are assembled in series to form higher voltages collectively in a module, the voltage becomes more dangerous. Again, special assembly tooling is used to protect personnel against accidental shorting. Once assembled it is important to protect personnel from this voltage during transportation, installation, commissioning and de-commissioning.


For this, SPBES uses a contactor inside the module to isolate the battery voltage from the battery terminals. This contactor can only be closed by the Battery Management System (BMS) during operation, therefore eliminating all voltage related hazards when it is not in use. The total battery voltage once installed is very dangerous considering we commonly install batteries at bus voltages higher than 700VDC and up to 1500VDC. The protection for this is done through proper isolation design, the use of breakers and independent safety circuits like high voltage interlocks, independent breaker trips and ground fault detection.


The system is also designed to reduce the voltage anywhere on the installation to less than 100V when the system is off. This ensures that any unintentional shorts will not result in a dangerously high current and potential damage to the system.


Thermal runaway is a potentially catastrophic hazard that must also be in the front of an engineer’s mind when designing a lithium- ion battery. It is rare that thermal runaway occurs, but the impact can be devastating when it does. Our design philosophy is to eliminate the risk completely through our patented cooling system, CellCoolTM.


Rather than trying to manage the potential consequences of a thermal runaway event, SPBES has always focused on removing this hazard completely. Even if the cell heats up, regardless of the reason, SPBES’ system can remove the heat quick enough to prevent thermal runaway from occurring. Additionally, SPBES’s cooling system protects the cells from external heat sources such as a fire outside the battery.


Our philosophy has always been and always will be to protect the vessel and crew to the best of our ability, incorporating new safety innovations from our R&D team as they become available.


ForSea Aurora travels from Denmark to Sweden using EV battery Propulsion


The Report • March 2020 • Issue 91 | 59


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