Since the launch of the refreshed version of the Model Y Performance At the end of 2025 in the United States, the first users reported a surprising phenomenon: a slower charging speed compared to previous generations. In question? A brand new battery cell and a cautious strategy from Tesla.
The transition to the “21VB” cell
Table of Contents
The heart of the matter lies in the change of supplier and technology. While Tesla historically used cells from the Gigafactory Nevada factory or from China, the new Model Y Performance produced at Giga Texas now integrates the cell 21VB.
- Origin : Made in the new giant factory of Panasonic in De Soto, Kansas.
- Format : This is an evolution of the 2170 format, optimized for increased energy density (+6% approximately).
- Objective : Allow the Performance version to achieve an EPA autonomy of 306 miles (492 km), slightly outperforming previous versions despite its 21-inch rims.
Why slower charging?
If you have taken delivery of this model, you may have noticed that the charging curve “stagnates” earlier than expected. Several factors explain this temporary restriction:
- A “conservative” load curve: As the 21VB cell is completely new, Tesla has implemented very careful battery management software (BMS). To avoid premature degradation before having millions of miles of real data, charging power drops faster after 20-30% battery.
- “Production Hell” in Kansas: The Panasonic plant in Kansas is still in the ramp-up phase. The first series of cells are undergoing drastic quality tests, which has also caused significant delivery delays in December 2025.
- Upcoming update: Tesla has a practice of “unleashing” power via over-the-air (OTA) software updates once the chemical reliability of the cells is confirmed by fleet data.
My Opinion: A necessary evil for future good
In my opinion, this situation perfectly illustrates Tesla’s philosophy: « Ship first, optimize later » (Ship first, optimize later).
The bet of sovereignty
This is a crucial step for Tesla. By relying on the Kansas factory, Tesla secures its American supply chain and ensures that its vehicles remain eligible for Federal Tax Credits. The temporary sacrifice of a few minutes to the Supercharger is the price to pay for independence from Chinese cells (LG/CATL) whose durability is sometimes debated.
Safety before speed
Unlike traditional manufacturers who freeze specifications when they leave the factory, Tesla treats its batteries like software. Clamping the load at launch is a decision responsible. We have seen internal resistance issues on some LG cells (NCM811) in the past. By being conservative with the 21VB, Tesla is protecting the resale value of the vehicle in the long term.
Conclusion
If you buy a Model Y Performance today, you are not buying a finished product, but a platform that will improve. In 6 months, it is very likely that a “magical” update will flatten the load curve and restore the nobility of the Performance badge.
