The short answer is that some 6% of the battery capacity is gone.

Bjørn Nyland's Tesla Model 3 Performance has 14 months and about 60,000 km (37,300 miles) on the odometer, which prompts this experienced EV enthusiast to conduct another battery degradation test.

It's an interesting use case, as Bjørn mostly charges at fast chargers:

  • DC charging total: 9,436 kWh (64%)
  • AC charging total: 5,252 kWh (36%)
  • Total: 14,688 kWh

After overnight charging to full, Bjørn went on a long journey at cruise speed (80-90 km/h) to see how much energy he is able to get out of the battery.

During the test, Bjørn estimated that the total energy available was 68.8 kWh, calculated as 66.4 kWh consumed, divided by state of charge (0.997-0.032) - 99.7% at the beginning and 3.2% at the end of the test.

The latest and previous results of total battery output (energy available) are as follows:

  • 27 April 2019: 73 kWh
  • 15 October 2019: 69.6 kWh (-2 kWh by software?)
  • 13 June 2020: 68.8 kWh

The short answer is that after 14 months and 60,000 km (37,300 miles) the car lost some 6% of the battery capacity (although some 2% might be related to a previous software update).

To better understand what is happening, another test is planned after the next six months.

Assuming that the 6% is a valid number and that the rate will stay like this, 80% of the initial capacity (20% degradation) will be reached at 200,000 km (124,300 miles), but that is only an extrapolation.