inetdog
The described problems leading to repeated over-discharge during ground operations has probably led to a greatly increased amount of cycling expansion and contraction compared to the predicted service life profile. Any additional complications from charge control anomalies and thermal expansion/contraction would only add to that.
I think it would be instructive to look at the construction of each cell. Two metallic foil layers, two "paste" layers, and one "Separator", of polypropylene/polyethylene... Laid up flat, on a bench, no problem. But then it is required to "roll" this strip into a rectangular shape. What is the composition of the binders for each paste? One for Graphite, the other for LithiumCobalt Oxide?
How do these layers react to the stress of assembly?
More importantly, and given the telling photography of the MAIN Battery stacks, how does this laminated stack perform in service?
If the MAIN Battery (the "Exemplar"), shows such obvious signs of deformation, are we seeing the prelude to failure?
Poly is NOT resistant to heat, the perforations can shut, and the output can become disoriented to the electrode. That the Stainless enclosure is deformed is instructive of the stresses involved?
It is not a stretch to go here, NTSB made suggestive statements as to this avenue of the investigation, early on....
