Lyman - #641,
The Battery install, however, suggests the only wiring external to the case is +/- conductors, and Ground. Would the diagnostics storage be co-located with the PCBs? Inside the case?
To the contrary, the charger and the battery case are connected by a multiple pin cable, and the PCB's located in the battery compartment are probably concerned with buffering bi-directional data between the units.
The THALES charger above and a close-up of the J1 circular connector under examination by NTSB is below. The battery case has the complementary data connector above the battery terminal connectors.
This link will provide a
large close-up of the front of the JAL battery case.
My guess is that THALES is the prime contractor and Securaplane is the sub-contractor providing the charger and BMS.
@ syseng68k
I suspect from what I see, that a great deal of data is being processed between the units.