In the 1960s, the automotive industry switched from 6V to 12V. (currently smaller vehicles might still use 6V, while larger vehicles use 24V).
Tesla made the transition from 12V lead-acid auxiliary batteries to 12V lithium-ion auxiliary batteries back in February 2021 and initially launched in the refreshed Tesla Model S/Model X (beginning with the Plaid). Later towards the end of that year, the company implemented the change to the Model 3/Model Y as well.
Old lead-acid batteries were a major source of failures in Tesla vehicles and needed to be replaced every four years or so. The new lithium-ion batteries are expected to last the life of the vehicle, so there should be no need for replacement.
Another added was the smaller size and lower weight (87 percent reduction). The new 48V goes further, when compared to 12V systems, it will reduce current by a factor of four. This level of voltage is still considered safe.
Tesla’s upcoming products, such as the Cybertruck, the Optiums robot, and all future electric vehicles, will use the 48V low-voltage system beginning this year.