Tesla shifts 4680 battery supply from Cybertruck to Model Y with charging speed and repairability implications

Tesla is making the 2026 Model Y with its own 4680 batteries again, it seems. The first such effort didn't end well, as not only was Tesla's first structural battery pack integrated in the chassis not repairable, but the inaugural generation of 4680 batteries had a low energy density and bad charging curve, too.

As a consequence, Tesla gave up on installing 4680 cells in the Model Y and developed a second generation of the battery with better energy density for the Cybertruck. The electric pickup, however, isn't selling, and Tesla is wondering what to do with it, as it outright decommissioned its two other premium vehicle models, the S and X, whose puny sales fell 50% in 2025.

The Cybertruck may be remarketed as an autonomous workhorse, said Elon at the Q4 earnings call. Until then, Tesla may have found itself with enough free 4680 battery capacity produced with the affordable dry electrode method to start equipping "certain Model Ys with our 4680 cells." The automaker cites supply chain challenges caused by tariffs as the culprit behind this move.

Tesla may be producing the 4680 batteries with dry electrodes and anodes on the cheap now, but their thermal inefficiency and charging curve are still lacking in comparison with the 2170 cells from Panasonic, though, so the news that 4680 batteries are back on the Model Y menu can leave future owners with mixed feelings.

There is some good news in the transition to Tesla's own 4680 battery cells that may otherwise be considered inferior to the 2170 packs in long-range Model Y trims. According to Tesla's CFO, its engineers have been "trying to resolve the [supply] situation by now putting 4680 cells in non-structural packs."

What this basically means is that the Tesla team now puts 4680 cells in the trays of the 2170 pack housing, potentially making the pack repairable by replacing only individual cells that have gone bad. Previously, Tesla used a cell-to-pack technology where the big 4680 battery was part of the Model Y chassis structure and simply filled the void between cells with copious amounts of impossible-to-remove adhesive, making the battery good until failure, when the whole thing has to be replaced.

Tesla stays mum on which exact Model Y versions are coming with 4680 batteries out of the factory, but inquiring minds will find out soon enough and put those through the charging curve song and dance to determine whether Tesla has fixed previous charging speed issues known from the Cybertruck or from the first-gen Model Y 4680 cells.

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