NTSB's press release (1/20/2013; emphasis is mine):
NTSB Provides Third Investigative Update on Boeing 787 Battery Fire in Boston
WASHINGTON - The National Transportation Safety Board today released a third update on its investigation into the Jan. 7 fire aboard a Japan Airlines Boeing 787 at Logan International Airport in Boston.
The lithium-ion battery that powered the auxiliary power unit has been examined in the NTSB Materials Laboratory in Washington. The battery was x-rayed and CT scans were generated of the assembled battery. The investigative team has disassembled the APU battery into its eight individual cells for detailed examination and documentation. Three of the cells were selected for more detailed radiographic examination to view the interior of the cells prior to their disassembly. These cells are in the process now of being disassembled and the cell's internal components are being examined and documented.
Investigators have also examined several other components removed from the airplane, including wire bundles and battery management circuit boards. The team has developed test plans for the various components removed from the aircraft, including the battery management unit (for the APU battery), the APU controller, the battery charger and the start power unit. On Tuesday, the group will convene in Arizona to test and examine the battery charger and download nonvolatile memory from the APU controller. Several other components have been sent for download or examination to Boeing’s facility in Seattle and manufacturer’s facilities in Japan.
Finally, examination of the flight recorder data from the JAL B-787 airplane indicate that the APU battery did not exceed its designed voltage of 32 volts.
In accordance with international investigative treaties, the Japan Transport Safety Board and French Bureau d'Enquêtes et d'Analyses pour la sécurité de l'aviation civile have appointed accredited representatives to this investigation. Similarly, the NTSB has assigned an accredited representative to assist with the JTSB’s investigation of the Jan. 15 battery incident involving an All Nippon Airways B-787. Both investigations remain ongoing.
Further investigative updates on the JAL B-787 incident will be issued as events warrant. To be alerted to any updates or developments, please follow the NTSB on Twitter at www.twitter.com/ntsb.
NTSB Media Contact:
Office of Public Affairs
490 L'Enfant Plaza, SW
Washington, DC 20594