Nothing ruled out as NTSB studies Dreamliner battery

Washington (CNN) -- As Boeing and airline officials sought to assure travelers of the overall safety of the world's newest jetliner, federal safety officials Thursday painted a graphic picture of a disaster averted, displaying the charred remnants of a battery that "spewed molten electrolytes" from its container shortly after landing in Boston earlier this month.
"This is an unprecedented event," National Transportation Safety Board Chairwoman Deborah Hersman said of back-to-back battery incidents aboard Boeing 787 Dreamliners in the United States and Japan.

These lithium batteries stores 6 times more power than a lead  acid battery used in a motor vehicle.
When the airline if in flight the batteries are not in use but they are constantly  being charged and naturally the electrolyte  will be overheated and explode

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