BT40: the 40 kWh pack

If the car is still limited, the extra capacity is physically there: ask whether the unlock was ever bought. Supercharging was not offered with the 40, but some 40 and 60 kWh cars bought before April 2015 were later given pay-as-you-go Supercharging, so plug it in at a Supercharger rather than take anyone's word for it. Rated at 139 miles by the EPA when new, it was the lowest-rated Model S. The pack code is the pack on Tesla's record for this car, usually the one it was built with: Tesla can update it after a replacement, and one done outside Tesla may not show. It does not change with software, and it is not always the badge on the trunk.

Older Model S and Model X pack codes carry the nominal capacity in their digits: BT40, BT60, BT70 and BT85. The 75, 90 and 100 kWh packs are recorded as BTX5 or BTX7, BTX4 and BTX6, and the report reads both forms. Two things the code does not tell you. First, the badge on the trunk is not always the pack: Tesla sold some cars as a smaller size than the pack inside, limited in software, and its record shows that in Tesla's trim code (a 60 on a 75 kWh pack, for example), not in the pack code, so the report says a pack was limited only when that trim code says so. Second, the pack code is the pack on Tesla's record for the car, usually the one it was built with: Tesla can update it after a replacement, and one done outside Tesla may not show. From 2019 the codes change form, BT37 and its successors, and the digits no longer encode capacity. For those the report uses the public option-code lists where they all agree, so BT37 is 75 kWh with Panasonic cells and BT42 is 82 kWh with Panasonic cells, and prints the code alone where they do not.

The free decoder reads the Full Self-Driving codes from the factory record for any VIN. The $1.99 report lists every other code. It also says whether the car can have free Supercharging, and how likely it is.

See a sample report →