never said it was batteries at fault, seen that some people reckon that a coffee boiler was left on and boiled dry, thermal cut out failed, and it caught fire, again will be interesting to see what the report says.
on other 787 news the Thompson 787 returned due to all but two toilets not working, some have suggested an electrical issue, are the toilets electrically powered on the 787? see
here Boeing do seem to have a few electrical issues on the electric jet, i guess to be expected.
Jason