48Vdc is supposedly the highest voltage that is still considered safe. (https://electronics.stackexchange.com/questions/267789/how-s...)
It certainly sounds like a smart move on the copper savings alone.
Tesla shares 48V architecture with other automakers
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Re: Tesla shares 48V architecture with other automakers
#12Why would a car need a 48V system for accessories? In general the things a car's 12V system powers have gotten less power hungry over time (LED's, heat pump) and in particular, an EV loses the highest power electrical device on the 12V bus, the starter. The typical equipment used for the entertainment and control systems are going to be much more available with 12V supplies, just because that's the industry standard.…
Like I said, the 12V bus in an EV isn't driving a bunch of high power stuff.
Take a look at the fusebox in any modern car, EV or not. (There will most likely be more than one fusebox.)
You'll see lots of 20A, 30A, 40A parts, some even larger. Running those circuits on 12 volts takes more copper than you probably think it does. More copper and beefier (read: much more expensive) connectors. The move to 48V is frankly overdue.
Re: Tesla shares 48V architecture with other automakers
#13Why would a car need a 48V system for accessories? In general the things a car's 12V system powers have gotten less power hungry over time (LED's, heat pump) and in particular, an EV loses the highest power electrical device on the 12V bus, the starter. The typical equipment used for the entertainment and control systems are going to be much more available with 12V supplies, just because that's the industry standard.…
Just to add the basic idea, the amount of power is amps * volts. So to carry the same amount of energy with a higher voltage, you can you use less amps. The amount of amps impacts how big the wires are, lower amps need smaller wires and that means less space for wires but more importantly less weight of the wires. There is a lot of wiring in a car. Tesla claims this could be 1/4 the amount of copper wiring in an article, below.
This article describes a bit about this, but also says something I never heard, that there were 6v auto systems in the 1960s. https://www.mining.com/new-tesla-low-voltage-system-a-big-de...
Re: Tesla shares 48V architecture with other automakers
#14Re: Tesla shares 48V architecture with other automakers
#15Why would a car need a 48V system for accessories? In general the things a car's 12V system powers have gotten less power hungry over time (LED's, heat pump) and in particular, an EV loses the highest power electrical device on the 12V bus, the starter. The typical equipment used for the entertainment and control systems are going to be much more available with 12V supplies, just because that's the industry standard.…
Power steering pumps are electric and have one of the largest wires in my truck. With an EV you also have a heat pump, maybe a heater, coolant pumps now that you don't a constant spinning pulley, windows, lights, headlamps, power doors, seats, radio, amplifier, small PC, etc.
From the article "Switching to 48V architecture alleviates a huge number of challenges automakers are facing with 12V. The biggest one, though, is complexity: You need far less complex wiring harnesses to power all your vehicle systems"
My take is that 12v requires almost a dedicated power line for each part, while a 48v could run to a bus line that gets tapped. 48v might be something that divides easier with the battery pack, and drops the 12v battery.
Re: Tesla shares 48V architecture with other automakers
#16Why would a car need a 48V system for accessories? In general the things a car's 12V system powers have gotten less power hungry over time (LED's, heat pump) and in particular, an EV loses the highest power electrical device on the 12V bus, the starter. The typical equipment used for the entertainment and control systems are going to be much more available with 12V supplies, just because that's the industry standard.…
Anything drawing over 250 watts is going to need over 12 gauge wire. I put a 2200 watt inverter in my truck and I needed to put 4/0 gauge cables to it which are huge. 48v would mean I could have gotten away with only 8 gauge wire.
Re: Tesla shares 48V architecture with other automakers
#17Why would a car need a 48V system for accessories? In general the things a car's 12V system powers have gotten less power hungry over time (LED's, heat pump) and in particular, an EV loses the highest power electrical device on the 12V bus, the starter. The typical equipment used for the entertainment and control systems are going to be much more available with 12V supplies, just because that's the industry standard.…
Here is an explainer:
https://youtu.be/ky1Z2klPalw?t=573
Transcript:
. . . a little bit about electrical electrical engineering um you don't need to know a lot but just a little bit uh we'll understand that you actually want a higher voltage in order to reduce the resistance losses.
So the heating in any wire is the current is the square of the current. So if you're trying to get a particular power rating through then as you increase the voltage you can decrease the current. Voltage times amperage equals your power. To hold power constant, the heating is is proportionate to the square of the current. So you want to raise the voltage in order to lower the current thus lower the heating in the wire.
And the net effect being that you can have much thinner wires, then as you raise the voltage you can you can drop the the the thickness of the wires. You can have much you can use much less, in a nutshell. You can use much less copper and the wire harness weighs much less as you raised the voltage.
Re: Tesla shares 48V architecture with other automakers
#18Do more stuff like this, Elon. I really don’t like not liking you.
weird comment... maybe we shouldn't feel the need to idolize humans...
We humans are all terrible on some level (except my mom, she was a saint), but if you have enormous power, you can help or hurt a lot of people based on your actions. Musk has a lot of power. He must be a terribly lonely person, not knowing if he can trust anyone or they just want something from him.
Re: Tesla shares 48V architecture with other automakers
#19Why would a car need a 48V system for accessories? In general the things a car's 12V system powers have gotten less power hungry over time (LED's, heat pump) and in particular, an EV loses the highest power electrical device on the 12V bus, the starter. The typical equipment used for the entertainment and control systems are going to be much more available with 12V supplies, just because that's the industry standard.…
The savings in terms of weight and efficiency are actually significant. This was covered in Tesla's investor day presentation earlier in the year:
The section on electronic architecture (~10min): https://www.youtube.com/live/Hl1zEzVUV7w?si=-Vz0gKT5YDbtrG9V...
The sub section (~4min) on 48V in particular: https://www.youtube.com/live/Hl1zEzVUV7w?si=shfI2vEz9taTLSm7...
Re: Tesla shares 48V architecture with other automakers
#20Why would a car need a 48V system for accessories? In general the things a car's 12V system powers have gotten less power hungry over time (LED's, heat pump) and in particular, an EV loses the highest power electrical device on the 12V bus, the starter. The typical equipment used for the entertainment and control systems are going to be much more available with 12V supplies, just because that's the industry standard.…
Some devices in a car are still pretty power hungry. Eg. The blower motor for the fan (typically 800 watts = 70 amps @12v). Heated rear screen (240 watts = 20 amps). Window motors are pretty powerful too.
End result is you need a lot of fairly chunky cables to power those things.
And the price of copper has been steadily climbing since 1960 - unlike other commodities which have been getting easier and easier to extract with more automation in mines.