NTSB Issues Recommendations on Lithium-Ion Batteries

AINsafety » May 26, 2014
May 26, 2014, 12:40 PM

The National Transportation Safety Board on May 22 issued five safety recommendations to the FAA related to the evaluation and certification of lithium-ion batteries, as well as the certification of new technology. The recommendations evolved through the ongoing investigation of a Jan. 7, 2013, lithium-ion battery fire aboard a Boeing 787 parked at Boston Logan Airport.

Investigators found that the battery showed evidence of not only thermal runaway but also of “unintended electrical interactions that occurred among the cells, the battery case and the electrical interfaces between the battery and the airplane.”


The 12-page safety recommendation letter said that the processes used in 2006 to support the certification of the lithium-ion battery designed for the 787 were inadequate, in part, because there is no standardized thermal runaway test that is conducted in the environment and conditions that would most accurately reflect how the battery would perform when installed and operated on an in-service airplane.

However, the safety agency said the lack of a standardized thermal runaway test–one of the items the NTSB has now called for–on lithium-ion aircraft battery designs currently in service might not have adequately accounted for the hazards associated with internal short-circuiting.

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Roger
on May 26, 2014 - 10:24pm

The NTSB mentions; “unintended electrical interactions that occurred among the cells, the battery case and the electrical interfaces between the battery and the airplane.”
 .................This issue has nothing to do with the  type of cell involved. 

This problem could happen with any cell type: A Lead-acid or Nickel-alkaline cell can suffer the same problem i.e. external short-circuit, BUT these cells cannot self-incinerate...........They have a lower energy-density but a higher cycle-efficiency. A battery can be charged as a unit without being concerned about how the individual cells are progressing.

This means Li-Ion cells have  much greater risk of overheating on excessive rate-of-charge and of course  they are combustible, so there is no limit to the damage which can result from incorrect charging. .

The best safeguard for Li-Ion cells is to monitor temperature closely at multiple sites on each cell and discontinue charging [or even disconnect the battery] if the cell begins to heat up.

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