Unlike with the v1 packs that have BMB issues, the ‘fatal flaw’ isn’t the BMB boards, but instead the design of the new sensor wire attachment. This Thread on TMC has some great information from AlphaTango11 and follow up discussion after post #65. The whole thread is worth a read as it has a bunch of great info.
It is believed that these failures have more to do with thermal expansion than with impacts and vibrations. The basic theory is the physical module expands while the ‘flex’ cable stays in position and the little welded connections on the copper pads fatigue and break off. The true answer could be a combination of factors but the bottom line is that the sense wires on these packs are much more fragile than the earlier version that uses the single stranded wire welded to the collector plate.
Everyone agrees these are difficult to reattach correctly. Some vendors are trying a conductive epoxy. Some suggest a solution like epoxy would be good to apply before the connections fatigue and break. These v2 packs just started coming off warranty in 2024 so before now pretty much only Tesla has been dealing with them.
V2 BMB
Can you find C26 and C27? Hint – they are protected in the center of the board now! Look at the bold stand-offs at each corner. It’s almost like Tesla learned from earlier mistakes…
V2 BMB
Tesla was proud of ‘Quadruple Redundancy’ but 4X isn’t that great if your X is garbage (sorry, I couldn’t resist). These sense wires seem to fail where the silver/stainless looking wires attach to the copper colored pads. The detachment seems to be more prevalent after collisions and more prevalent on Brick #3 which hangs from the underside. My theory is one or more of them break during the accident and the rest are weakened by fatigue/flex when there are fewer of them holding everything still. My theory, however, is worth what you paid for it since I have never seen one of these in person.
