They cannot be recharged aboard the airplane. They can be recharged on the bench. This information comes from 787 Electrical Engineers with direct knowledge of the procedures.
According to the information, over 150 batteries have been sent back to Yuasa, because once they hit that point, the system will not allow it to be re-charged.
It goes further to say that the cost is $16K per cell...
Whos bench, YUASA's...how convienent...
If you have a direct connection with the EE at Boeing, ask them why they designed such an F'd Up system....
The A350 will be flying before the B787 will....