You can replace a Model S/X 60, 70, 75, or 85 kWh battery with a larger battery pack, such as a 90 kWh pack. The 100 kWh pack is incompatible and uses different connectors and fluid fittings. Due to the extra weight of the 100 kWh pack, the suspension was changed and the airbags were calibrated for these changes. (May-2024)
Changing the pack size requires more work than simply swapping the battery. In addition, software changes are made, and some required changes are not available even to those with access to Tesla’s Toolbox 3.
Tesla’s cost for a battery replacement is around $20-22K for a new 90 kWh pack and installation labor. In some cases, a refurbished pack is available at a lower cost. Both include a warranty.
One company that offers trusted battery pack upgrades is Recell. They offer a warranty on their work as well.