It's the chemistry of the batteries.

Tesla uses a more volatile mix, gives them better transient response of currents in and out and slightly higher energy density. That later part they don't have a choice, as they uses universal pre made cylinder cells to make up a pack, others use punch style cells which are more space efficient but is model specific. . The downside is higher self sustained combustion chance. They are the only one using that, and they deems the fire risk acceptable. 

 


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