Five years after Tesla (TSLA) unveiled its 4680 battery cell at Battery Day with promises of 5x the energy, 6x the power, and 16% more range, the data tells a very different story. Tesla’s homemade cells consistently deliver worse energy density, worse charging performance, and less range than the supplier cells they are meant to replace.
The problem is getting harder to ignore now that Tesla is quietly swapping supplier batteries for its own 4680 cells in European Model Y vehicles — and owners are noticing the downgrade.
*At Battery Day in September 2020, CEO Elon Musk presented the 4680 cell as a revolutionary leap. *
Tesla said the cells would improve range by 16% at the pack level, cut costs in half, and enable a $25,000 electric car.
Here is what the actual data shows after five years of production:
Energy density: Tesla’s 4680 cells produced at Giga Austin have a nominal energy density of 244 Wh/kg. The Panasonic 2170 cells they are meant to replace sit at 269 Wh/kg. That’s 13% worse, not better. Tesla claimed higher density in the latest version, but they haven’t been tested yet.
Battery capacity: The new 4680-based “8L” pack going into European Model Y vehicles carries approximately 79 kWh gross (74 kWh usable). The LG 5M pack it replaces in the exact same trim — the Model Y Premium Long Range RWD — had 82-84 kWh. That’s roughly 3-5 kWh less energy in the same car.
Range: The direct consequence is a WLTP range drop from 661 km to 609 km on the European Model Y Premium Long Range RWD. That’s a 52 km reduction — an 8% downgrade on the same vehicle with the same aerodynamics and the same motors. The only variable is Tesla swapping an LG battery for its own 4680 pack.
Weight savings: Tesla’s original pitch for the 4680 structural pack was significant weight reduction. Munro’s teardown found a difference of just 20 pounds between the 4680 Model Y and the 2170 Model Y. European certification data for the 8L pack shows a mass of 447 kg.
And the 4680 takes longer to charge.