Good information in the case of a warranty replacement, which this was not.
Fair, but many insurance policies (and expensive parts sourced from the manufacturer, which this is) replace with refurbished units of equivalent performance. That is, not always new parts.
Even with new parts in a non-warranty scenario, the rest of what I said is applicable.
that would seem odd as i.e. a failing battery will degrade quicker and it isn ot what other people have observed with battery replacements.
Also bit of a chance for them to find a replacement battery with exactly the same degradation.
If i get 20% degradation over the next year and then get battery failure warnings (which is likely with such quick degradadation) then i sure hope i get a replacement with <5% degradation ,just like all other packs with low milage.
It's not the best policy for the owner, no. In practice Tesla has trended towards being generous of course, with the fine print allowing them to not be so.
For sure the BMS itself was replaced; it is part of the battery. I do wonder about where the tracking information on the battery is stored, though (the CAC value). If that is stored elsewhere, maybe that info was not reset as part of the replacement?
No idea really. I guess if I were the OP I would at least contact Tesla and see if they can do a CAC reset remotely. It’ll probably sort itself out, but no idea.
I
think (I'm far less sure about this) that the CAC values are in two places: the 4x BMB boards that rest on the four modules within the main pack compartment,
and the BMS bits in the penthouse (which collects data from the 4x module boards). I was thinking of the penthouse components when I said it was probably replaced as well.
Since their architecture is fairly modular between these subsystems, I very very highly doubt the CAC values are stored or cached anywhere else that's used to display the range to the driver. But it's possible.
I wonder whether the historical data collected by the BMS is stored and processed by the central CPU for range calculations and the like? If so, I have no idea whether Tesla can/does reset the data on pack replacement.
With very high confidence, I do not believe a component outside the battery pack is ultimately responsible for being a source of truth for the battery capacity. I don't know where the range calculation occurs technically, but it's simply based on communicated stats from the battery and an efficiency constant (based on model, year, wheels). When things like temperature impact the usable energy (and thus range), this is still being communicated by the battery pack itself from what I understand.
