@turbine D......All this bullcrap !- the great Victorian engineering miracles were done on a handshake and trust!
The fact is, the complete battery sub-assembly is provided by THALES
As far as the customer (Boeing) is concerned, the box-contents are irrelevant, PROVIDED it "does what it says on the tin"...the onus is surely on Thales and the regulatory body ,to make sure this is the case?
Which leads to SECURAPLANE (ironic?)....their job was to supply a plug 'n play interface between the "screamliner's" electrical supplies/demands and Thales' "5-minute box of energy"
However you pass the parcel, waffle and apportion blame, the fact is, the interface between these 3 groups failed to work.
As the Securaplane device is INTERPOSED between the aircraft and the "energy-box" I suggest that it failed miserably in it's duty to protect, manage and monitor the use and availability of that resource.
The Lithium Cobalt cells are "fragile" technology..for safety, they should ONLY operate in the mid-area of their capacity-range...charging towards ultimate capacity can lead to instability, discharging to low level has the same effect.
THE VERY FACT THAT SO MANY OVER-DISCHARGED UNITS HAVE BEEN CHANGED WOULD SEEM TO CORROBORATE MY ASSERTION
SECURAPLANE'S UNIT IS NOT SUITABLE FOR THE APPLICATION.
Wether this is due to Boeings failure to accurately specify what it needed, or Securaplane's lack of understanding the battery technology it was supposed to be taking-care of is another issue.
To the poster who suggested that a main-battery discharge may well be unmonitored....NO!....It's inconcievable and absurd to suggest that an unlimited current -draw in total-faliure mode would be OK....so you're suggesting that it's better to avert the power-failure crash and substitute on-board fire instead?
