I’m not arguing that the cars wouldn’t be safe, or that you or I wouldn’t make the switch. I’m just saying that service centers won’t put a 100 in a 90 without changing the seats, because the crash tested seat combo was different. (and both are 16 module) So now the service center is replacing 60s with 90s without changing the suspension? (14 module to 16 module)
I am genuinely curious since I hear the service centers are putting 75s in 60s. (Both 14) Are the service centers including suspension changes in these quotes or are they more relaxed with individual cars than they were with a publicized upgrade?
The seats are identical also. The
only changes between vehicles based on battery pack size are with coil suspension vehicles to tune fully-loaded ground clearance to be whatever is required. The weight differences are pretty negligible even in the worst possible case like an original 60 to a 100. In the bulk of cases a change wouldn't even be noticeable. The crash related systems are identical on all variants, and the software has zero changes depending on battery size. Vehicle with air suspension are all completely identical, as the car just adapts to the weight of the pack regardless.
TLDR: There are zero safety implications in putting different packs in a vehicle, regardless of how it was "born." No additional changes to the vehicle are needed even from a practical standpoint in 99% of cases. (I'd probably suggest swapping the coils if going from a 60 to a 100, but that's not a super common request anyway.)
The max weight delta between an original 60 and 75 is something like 75 lbs... basically a rounding error. In the case of some of the 60 pack variants, the new 75s weigh
less than the original 60s due to design improvements... and significantly less than some variants (as much as ~50 lbs or so!) So I don't think it makes a difference either way, and Tesla is just doing this now because there's no production of the old 60s and they're nearly impossible to refurbish.
Based on everything I've learned over the years, I firmly believe Tesla's original thinking on not doing upgrades had absolutely squat to do with vehicle side differences, safety, etc with the pack sizes (since these are effectively non-existent, despite being a potential excuse) and more about driving new car sales. Why would a customer buy a new 100 vehicle for $100k when they can spend $way_less on an upgrade of a vehicle that just missed the mark or whatever the case may be? Even if most people interested in upgrades don't buy new instead, every upgrade is a new car they're
definitely not selling. A simply policy decision that costs them nothing and probably contributed to some non-negligible percentage boost to sales.
Edit: Oh, the note about the seat thing finally clicked. Originally there was no combination of software that would work on a 100-equipped vehicle where the seats and a few other things (like, only dual motor) didn't line up. This had nothing to do with safety of general compatibility and was just "we're running out of space on the MCU to cram
all of these different configurations into the firmware image." At one point on MCU1 they were pushing it to within bytes of max size. They eventually culled down the firmware bloat and pretty much every combination is available, except for a RWD 100, by default.