A fire occurred in the battery compartment of the hybrid tug Campbell Foss just after the tug finished a ship assist in the Port of Long Beach. The vessel’s engineer was hospitalized.
Technicians blamed the blaze on a software error that caused long-term overcharging of the lithium polymer batteries.
The fire started at about 1540 on Aug. 20. It spread from the battery compartment through a ventilation duct to the engine room, according to Scott Merritt, senior vice president of operations at Foss Maritime Co.
The fire started just after Campbell Foss finished an assist, when the tug was mid-channel, just south of the Vincent Thomas Bridge, according to Will Nash, a firefighter with the Long Beach Fire Department.
The Foss tug Alta June went to the assistance of Campbell Foss and towed it to a nearby, empty pier. The fire was extinguished after the crew engaged the engine room FM-200 fixed fire suppression system, Merritt said.
The Long Beach Fire Department used its thermal imaging camera and found the fire was not spreading. Then they went and put out what was left of the smoldering fire, Nash said.
The tug’s engineer suffered smoke inhalation, according to Nash. He was treated and released that evening, Merritt said.
Campbell Foss is one of two 5,100-hp tugs using Foss Maritime’s patented Green Assist hybrid technology. It began operations at the port Jan. 29.
Campbell Foss has 10 Corvus lithium polymer batteries. These batteries provide a source of power that is more efficient and less polluting than diesel engines that run all the time. The batteries are tied electrically to a switchboard to provide another form of power, in addition to the tug’s two Caterpillar diesel engines or the two Teco-Westinghouse motor/generators.
The fire was caused by the failure in a series element in one of the 10 Corvus lithium polymer batteries, according to Merritt. After inspecting the other nine batteries, Foss found that the failure was triggered by a series of overcharging events over two months.
The battery monitoring system pack controller monitors the voltage of the individual series elements and reports the state of charge based on the lowest series element voltage, Merritt said. Sensors are embedded in each battery to monitor temperature. If there is excess voltage or temperature, the pack controller is designed to open its contactors to protect the battery from additional charge or discharge.
In this fire, a software error in the pack controller prevented this safety measure from operating, according to Merritt. The glitch led to a series of overcharge cycles, causing the lithium ion polymer cells in the battery to fail. Once the fire started, failure of the vent ducting in the battery compartment allowed hot gases to get into the port aft engine room.
Corvus Energy, the battery manufacturer, and Aspin Kemp & Associates, the hybrid system integrator, worked with Foss to find out what happened.
Campbell Foss will not return to service until it has undergone recommissioning dock and sea trials, according to Merritt.
The U.S. Coast Guard is investigating the fire.