Why now? What is different in the conditions to this point and the test parameters checked to this point in item and system qualification that is causing the batteries to fail?
Over charging by ground crews? Defective battery lot produced by the supplier (if so why did ATP test not find the issue)? Throw you own guess in with lots of questions that I am sure everyone possible is chasing to the ground with 50 180 mil dollar aircraft sitting on the ground.
As in the fuel used to run the engines these batteries store energy at high densities. When any high energy density system storage container or distribution system fails to manage the energy storage or transfer properly bad things will happen.
Bottom line I like Boeing and the FAA to be cautious and follow the proper analysis that we as QA professionals like to harp about and not jump to conclusions or preconceived paths. Keep everything on the table as a possibility and properly check each item out. Till then act on the side of caution and ground the fleet since any ignition source in an aircraft including bic lighters is something to avoid.
Anyone who travels a lot who thinks that the number of issues with the 787 aircraft is out of the ordinary just think back on the number of flights you were scheduled on have been delayed or canceled to a mechanical issue (yea I know we think that the airlines do this to avoid flying a less than full flight). Not a month goes by that I am not subject to one.
Just do what it takes to keep me safe since I am on these flying tubes way to much of the time.