The Tesla Cybertruck And Industry Standards

Telsa has finally starting selling its weird modernist looking, stainless steel, bullet proof cybertruck. A tweet at X explains another thing about the new model that is a landmark change in automative electronics standards:

Techies are obsessed with Cybertruck's 48 volt architecture. 12 volt has been the standard for over 50 years, though a 1965 VW bug actually had a 6 volt system. . . . 

The reality is that the car industry has been moving toward 48V for the last decade. But it's a difficult transition. Part of the reason is that we've moved from MECHANICAL linkages to ELECTRONIC. Things like the air conditioner, power steering, and power brakes tapped into the main engine mechnically. Power brakes, for example, were powered by the vacuum generatedby the engine. Even the original Tesla Model S didn't have electronic brakes -- it had an electronic device generate a vaccuum, which then powered normal brakes. 

Nowadays, everything is electronic, not just in electric cars, but in traditional gasoline cars as well. Lower voltage means power needs to be delivered by thicker copper cables, which now becomes a major expense for the car, as well as an extra hundred pounds of weight to carry around. 

Increasing the DC voltage to 48V from 12V reduces the the copper thickness by exactly 4 (Ohms Law), reducing the cost and weight of copper by 75%. 

Specifically, one of the things driving the change is "Power over Ethernet". I know what you are thinking, WTF is Ethernet doing in a car??? 

Here's the deal. There are cameras throughout the car now that need to send hi-def video from the edges of the car to the central computer. This far exceeds the bandwidth of old technologies so they are using gigabite Ethernet these days. They've developed a special wiring standard that needs only a single pair of copper wires for both transmit and receive ("Single Pair Ethernet"). They've also developed enough technology to use that same pair to transmit power. These cameras use several watts of power, so would otherwise need additional cables for power. Single-pair Ethernet carrying power thus solves a ton of requirements for car makers. The desired voltage of such systems is 48 volts. 

The same revolution is happening for consumers, by the way. The USB C Power Delivery standard maxes out at 48 volts when you try to power your laptop at 240 watts. Power = volts times current, and USB cables support a maximum of 5 amps of current. 

48 volts is where government regulators have decided that DC electronics are "safe" from electrocuting people. Getting much beyond that introduces a whole new level of government interference and regulations. 

Thus, 48 volts is probably going to be the standard for cars, Ethernet, and USB for the next hundred years. 

Tesla's Cybertruck is making the jump early. . . .  it's likely going to result in a lot of recalls as Tesla makes fixes. But that's okay for a low-volume, new product. What Tesla doesn't want is to change to 48 volts in a Model Y and suddenly have to do a recall of a million vehicles. Cybertruck is a good test platforms to get it working. Presumably, we'll next see it in the higher end Models S/X, and then eventually in the Models 3/Y.