The automotive industry latched on to 12-volt electrical systems in the Fifties and hasn't changed since. Even hybrids and EVs with high-voltage traction batteries still have a 12-volt battery to run things like window regulators, seat motors, headlights, and more. While we've seen several 48-volt "mild-hybrid" vehicles over the years, Tesla is the first to go 48-volt on a pure EV with the Cybertruck, and its marketing team wants you to know about it. 

"The entire supply chain, the entire design infrastructure is designed for 12 volts," Musk said in an interview. "This is why it's been stuck at this absurdly low number for a long time." It's something he feels passionate about, so much so that Tesla sent a manual on how to build a 48-volt car to the CEOs of major automakers, something Ford head Jim Farley confirmed on Twitter. 

It seems like another instance of Tesla breaking new ground, forcing legacy companies to play catch up. Think over-the-air software updates, or more recently, Gigacasting. The Cybertruck's switch to 48-volt electrics is being pitched as the same, but as always with Tesla, there's truth to parse from its hyperbolic messaging. 

First off, why is upping voltage a good idea? Ohm's Law tells us that voltage is equal to current times resistance (V=IR). Assuming a fixed resistance, raising voltage lowers current. Lowering current means you can use smaller wires to transmit the same amount of power. This saves weight, money, and improves vehicle efficiency. Higher current also corresponds to more energy lost as heat. A 12-volt system is therefore not only inefficient at higher power levels but requires components to have larger heat sinks than higher-voltage systems.

Automakers shifted from 6- to 12-volt electrics in the 1950s to address growing power needs posed by more advanced electrical components, especially ignition systems for higher-compression engines. Since then, the industry has generally stuck with 12-volt electrics, even as the number of electrical systems within cars has grown tremendously.