The New York Times website currently shows as part of their January 30, 2013 content a story which leads with some details of (apparently for cause and unscheduled) removals of battery packs in the ANA fleet in the months before the recent unpleasantness.
This link is quite likely to a point behind their paywall, but even so may be useful to some of you who subscribe.
NYtimes battery removal article
It says that ten batteries were replaced. It mentions that in three cases the charger was replaced along with the battery. It quotes a GS Yuasa spokesman as stating that battery exchanges are part of normal aircraft operation, but gives no data from any source to provide context on whether this removal rate should be considered unusually high save for the GS Yuasa comment and a Boeing comment that the batteries were not lasting as long as intended.
This is hardly proof, but to my eye is an additional suggestion that the actual operational environment on the aircraft is not compatible with the actual battery packs as delivered. A (rather distant) analogy might be the way certain socket locations on certain aircraft have been known to exact a severely reduced lifetime from incandescent bulbs because of excess vibration.