Subject

Lithium-Ion Battery Fire

Abstract

A lithium-ion battery undergoing characterization testing in a basement laboratory overheated, caught fire, and detonated, funneling toxic fumes into the two upper floors of the office building and forcing its evacuation for several days. Conduct a hazard assessment specific to the battery type, assure that research-type battery testing and storage conforms to safety standards, reassess the potential for exhaust systems to spread fumes throughout a building, and implement test configuration improvements for batteries to be used by flight projects.

Driving Event

During a lithium-ion (Li-ion) battery test on October 20, 2009, the battery overheated, caught fire, and detonated within an enclosed steel locker in a bunker attached to a multi-story, office/laboratory building at the NASA/Caltech Jet Propulsion Laboratory (JPL) (References (1) and (2)). The bunker was specifically designed for the purpose of containing the effects of such a battery failure. An adjacent locker, containing an identical battery in a controlled test configuration (i.e., the control battery) began to experience sympathetic heating conditions due to the initial fire, such that a portion of it deflagrated and was partially consumed by fire. The 30V, 15Ah-rated Li-ion battery, designed as a workhorse (test) battery, was not destined for use on a specific spaceflight project. Instead, it was being tested under ambient conditions to establish performance characteristics when used with high frequency, high-current ripple, power systems typical of many low Earth orbit (LEO) spacecraft.

The test batteries were placed inside sheet metal lockers, similar to a typical gym locker, with a ventilated hinged door (Figure 1). The lockers were arranged on the facility floor in sets of six, with wiring routed through an opening punched into the back of the locker (Figure 2). The incident occurred after the batteries had been under the same test setup and conditions for eighteen months and exhibiting nominal behavior.

Figure 1 is a color photo of an enclosed room. In one corner of the room, two sets of metal lockers (each is 3 doors high) are blackened from fire. In the middle of the floor, a layer of ashes and partially consumed components are visible. The walls of the room do not appear damaged............................... Figure 2 is close-up color photo of two metal locker cells stacked vertically. The metal doors are open, and the inside of the doors and inside of the lockers are blackened. In each of the two cells, one or more wires pass through the rear of the cell via a small hole.
Figure 1. Battery test facility following the fire Figure 2. Close-up of metal lockers used for battery test

When the battery fire erupted, smoke detectors actuated the fire alarm. The building occupants immediately evacuated the building without injury. There was no collateral fire damage because the JPL Fire Department provided a timely and effective response using a Metal-Ex fire extinguisher appropriate to dowsing a lithium fire. Because of the proximity of the battery bunker to the building ventilation air intake, smoke and toxic fumes from the combustion of Li-ion cell materials were vented into the rest of the building. The entire building was inaccessible for several days until air quality samples could be analyzed and hazardous materials remediated throughout the building.

The battery fire was caused by a faulty measurement of the battery terminal voltage, sent to the support equipment that controlled battery charging and discharge, that was intermittent instead of continuous (Reference (3)). Loss of this measurement resulted in continuous charging of the test battery until the temperatures and internal pressures within the 80 small individual cells led to detonation and fire. A JPL failure investigation attributed the root cause to inadequate knowledge and training of test personnel. Contributing causes were use of faulty EGSE and inadequate battery thermal protection. A proximate cause of the contamination of adjacent facilities was the design of the facility ventilation and air intake systems.

References:
  1. JPL Mishap Report No. 1984, October 21, 2009.
  2. NASA Incident Report No. S-2009-293-00007, October 20, 2009.
  3. Stephen S. Greenberg, "JPL Investigation of the [name omitted] Lithium Ion Battery Fire - Test Failure Analysis Technical Report," JPL Document No. D-64869, April 2, 2010.
  4. "JPL Standard for System Safety (JPL D-560)," Rev. D, JPL Document No. 34880, September 17, 2007.
  5. "Process for Ensuring Personnel/Facility/Operational Safety During Research and Development Testing," JPL Corrective Action Notice (CAN) No. 1597, March 25, 2010.
  6. "Procedures and Processes for the Testing and Storage of Various Type of Cells and Batteries," JPL Corrective Action Notice (CAN) No. 1594, March 25, 2010.
  7. "Operation of Exhaust and Ventilation Systems to be Assessed for the Safe Exhausting of Products in the Event of a Battery Fire in Labs 277-120, 125 and B25/26," JPL Corrective Action Notice (CAN) No. 1595, March 15, 2010.

Lesson(s) Learned

  1. The potential hazards of battery testing and storage suggest that the handling of batteries undergoing research and development should meet safety standards similar to those governing handling of flight batteries. There may be other hazardous research and development testing at JPL where test personnel are not aware of, or not trained in, the assessment of safety risks. The battery test was a research and development activity and not the flight hardware validation that is explicitly governed by Reference (4).

  2. Battery fires are not unusual occurrences, as batteries are sometimes tested to failure. However, the hazardous battery test procedures that led to the incident did not have adequate fault protection controls.

  3. The fire alarm triggered the evacuation of the office building. Combustion products from the battery fire in the bunker entered the ventilation intakes for the upper floors of the office building.

  4. In addition to facility lessons learned, the incident suggests test configuration improvements for implementation by flight projects that wish to use similar Li-ion batteries.

Recommendation(s)

  1. Where warranted by the severity of the potential hazards, augment the pre-operational safety review (OSR) for a test facility with a hazard assessment specific to the type of test article (i.e., battery type) and type of test. (See Reference (5)). Assess risk and communicate the risk posture to line management.

  2. Battery testing and storage procedures and processes must assure the safety of personnel, facilities, and hardware, and conform to safety standards. (See Reference (6).) Verify EGSE (battery charger, controller, etc.) has appropriate fault protection in place, and demonstrate that it operates as specified to bring the test to a safe condition.

  3. Reassess building ventilation system intakes in proximity to the exhaust from co-located or nearby laboratories that handle or store hazardous materials. (See Reference (7).)

  4. NASA flight projects that wish to use such Li-ion batteries should consider test configuration improvements:

    • Verify the operation of redundant voltage taps. (Redundant voltage taps are not provided on workhorse batteries. More important, test engineers should recognize when equipment becomes faulty and remove it from test until the equipment is repaired or replaced.)

    • Verify the as-built battery thermal conductance implementation. (Not a feature on the involved workhorse battery. Test engineers should recognize that thermal management is a consideration in future testing and account for it with appropriate test setup design/ventilation provisions.)

    • Review the implementation of battery charge and conditioning management, including worst case thermal environments, faulty charge equipment, and faulty sensors.

    • Conduct a hazards assessment that addresses worst-case events occurring throughout the entire battery charge/discharge cycle, and verifies that appropriate mitigation measures are in place for each worst-case event.

Evidence of Recurrence Control Effectiveness

JPL Corrective Action Notices (References (5), (6), and (7)) call for improvements to battery testing, storage, and hazard assessment, and for re-assessment of ventilation systems that exhaust air from the JPL battery laboratories.

Program Relation

N/A (R&D task)

Program/Project Phase

Not Applicable » Pre-Phase A

Mission Directorate(s)

  • Aeronautics Research
  • Human Exploration and Operations
  • Science

Topic(s)

  • Accident Investigation
  • Energetic Materials - Explosive / Propellant / Pyrotechnic
  • Facilities
  • Fire Protection
  • Ground Equipment
  • Hardware
  • Hazardous / Toxic Waste / Materials
  • Occupational Health
  • Risk Management / Assessment
  • Safety and Mission Assurance
  • Test Article
  • Test Facility
  • Environmental Control and Life Support Systems
  • Power
  • Spacecraft and Spacecraft Instruments
  • Advanced planning of safety systems
  • Early requirements and standards definition
  • Product Assurance