Comment by amelius
8 hours ago
Yikes, that sounds dangerous.
I'd personally prefer e.g. 48V even if that meant some more losses and/or thicker cables.
8 hours ago
Yikes, that sounds dangerous.
I'd personally prefer e.g. 48V even if that meant some more losses and/or thicker cables.
> Yikes, that sounds dangerous.
It is.
> I'd personally prefer e.g. 48V even if that meant some more losses and/or thicker cables.
That's unfortunately not an option. The problem with the 600 to 1000 V domain is that it is able to creep where lower voltage would stay constrained and high enough that it can jump small gaps and start arcing spontaneously. The fact that it is DC makes it more dangerous still. But from an economy and practical engineering perspective it makes perfect sense. Keep in mind that these cars are often built using Lithium-Ion packs (though fortunately we are finally seeing a change here towards safer options, even if they are slightly less dense and more expensive), so the electrocution risks are small compared to the thermal runaway risks.
Running an EV off 48V would lead to a heavily, heavily compromised vehicle. There just aren’t components that can handle 5-10kA of current with a reasonable size.
What parts of the car need that amount of current?
Are you talking about the charging circuitry?
What are the requirements for the motor(s)?
Both as you mentioned. Charge circuitry for DCFC can be >200kW.
Motors, for instantaneous current, can easily exceed 100kW, some much much more than that.
Even assuming limitations to 100kW (which, would be very low for motor current), that's still 2000 amps at 48V. Remember, 100kW is ~134 hp.
Charging speed is directly related to the voltage of the pack. Even if your own vehicle had arm-thick cables to support high speed charging at 48v there is no quick charger in the world that could support it. You would be stuck in the bad old days of needing hours to recharge the battery on your EV.
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