U.S. National Transportation Safety Board (NTSB) is investigating whether tiny fibre-like formations, known as dendrites, inside the lithium-ion batteries could have played a role in battery failures on two Boeing 787 Dreamliners last month, reports Bloomberg.
The crystals known as dendrites, which can cause lithium-ion batteries to short-circuit and fail, aren’t a central focus but are among areas under investigation in Boeing 787 Dreamliner’s fire and smoke incidents, the NTSB said.
Dendrites accumulate as a battery is charged and discharged, and can cause short circuits, according to battery experts. The particles are among several areas under investigation that could have caused one of eight cells within the battery to short-circuit and burn, igniting adjacent cells, Kelly Nantel, spokeswoman for NTSB said.
According to Nantel, dendrites are difficult to detect in batteries because they react in air and have to be examined in an environment of inert argon gas. It would be impossible to detect them in a battery that had already burned.
Boeing did not immediately respond to a request for comment. The planemaker completed what it called an uneventful test flight of a 787 dreamliner on Saturday, its first since the lightweight, carbon-composite aircraft was grounded.
The other factors under investigation are the state of charge of each cell and the method and delivery of that charge, contamination, electrode folds, wrinkles and pinches, and the assembly of the cells and battery.
According to reports, the NTSB is also looking at the total design of the battery, including the physical separation of the cells, their electrical interconnections and their thermal isolation from each other.