Conflicting reports paint two entirely different pictures of Tesla's flagship 4680 battery cell, leaving investors to question whether it's a breakthrough or a bust.
A regulatory filing in China suggests Tesla Inc. has achieved a major breakthrough with its second-generation 4680 battery, boasting 11.5% higher energy density and megawatt charging capabilities. But in Europe, customers are canceling orders for new Model Ys equipped with 4680 cells, citing an 8% reduction in range and painfully slow charging speeds compared to cars with supplier-made batteries.
The dueling narratives stem from what appear to be two different versions of the 4680 cell. A document submitted to the California Air Resources Board (CARB), first reported by Chinese media, details a "Cybercell" with an energy density of 272 Wh/kg, a significant jump from the 244 Wh/kg in Tesla's first-generation 4680s. This new cell also reportedly supports 1.2 MW charging, a key feature for the Tesla Semi.
The data from Europe, however, tells a different story. Tesla recently began shipping a Model Y Premium Long Range RWD with a new 4680-based "8L" pack. This vehicle has a WLTP range of 609 km, a 52 km or 8% drop from the 661 km range of the same model equipped with an LG Chem battery pack. The 10-80% DC fast-charging time for the 4680-equipped Model Y reportedly exceeds 35-40 minutes, far worse than the sub-30-minute times for supplier packs.
The divergence raises critical questions for investors about the success of Tesla's multi-billion-dollar bet on vertical integration. The 4680 cell, unveiled in 2020, was promised as the key to unlocking a $25,000 EV and halving battery costs. Five years later, the program's progress appears fractured, with high-end promises for niche products undermined by real-world downgrades in its best-selling vehicle.
The Bull Case: A 'Cybercell' Breakthrough?
The bull case for the 4680 program hinges on the second-generation "Cybercell" detailed in the CARB filing. This cell is reportedly being mass-produced for the Cybertruck and Tesla Semi. The 272 Wh/kg energy density, if accurate, would place it ahead of Panasonic's 2170 cells (around 269 Wh/kg) and on par with next-generation cells from CATL that are not expected to be in mass production until late 2026.
According to analysis of the filing, the performance leap comes from two key improvements. First, a 42% reduction in the cell's steel casing thickness from 0.6mm to 0.35mm, which reduces weight and frees up internal volume for more active material. Second, an upgraded cathode chemistry, moving from NMC 811 to a higher-nickel NMC 955 composition, which increases the density of the active material itself.
These advancements, combined with a dry-anode manufacturing process, are what theoretically allow for the 1.2 MW charging speeds. If Tesla can scale this technology, it would represent a significant competitive advantage, particularly for the commercial trucking sector.
The Bear Case: A Downgrade for Model Y?
The optimism surrounding the Cybercell is completely at odds with the experience of Model Y buyers in Europe. The introduction of the 4680 "8L" pack has been met with anger and order cancellations as customers realize they are paying the same price for a car with less range and worse charging performance.
The charging curve is particularly damaging. Independent tests show the 4680-equipped Model Y's charging power drops below 100 kW after reaching just 35% state of charge. One test found it added less energy in 15 minutes than a cheaper, smaller LFP battery pack.
This poor performance is compounded by supply chain data that suggests a lack of demand for the 4680 cells. In a recent filing, South Korean supplier L&F disclosed that its $2.9 billion cathode contract with Tesla for 4680 production had been written down by 99.9% to just $7,386, citing a "change in supply quantity." This aligns with reports that Cybertruck production is running at a small fraction of factory capacity.
Two Cells, Two Stories
The most likely explanation for the conflicting data is that Tesla is producing two distinct grades of 4680 cells. The high-performance, second-generation "Cybercell" appears to be reserved for the low-volume Cybertruck and Semi, where its performance can be advertised as a halo feature.
Meanwhile, a different, and evidently inferior, version of the 4680 is being installed in the mass-market Model Y. This could be a first-generation cell or a cost-optimized version that sacrifices performance. By quietly swapping its own underperforming cells for superior supplier cells in its highest-volume vehicle, Tesla risks damaging its brand reputation for technological leadership, especially as it refuses to disclose to customers which battery they will receive.
This article is for informational purposes only and does not constitute investment advice.
