24V is common in trucks, and yet never made it to regular cars because there was never sufficient reason.
Using a higher voltage is not an innovation (it's an obvious change, and we've gone from 6V to 12V to, in some cases, 24V already) - rather it's just a slight efficiency improvement in largely non-critical systems, with not a lot of incentive to take on the cost of transition.
In a a personal ICE vehicle, the only real significant power was to the starter motor and from the generator, and the distance there was short so the copper didn't really matter and thus no one cared for 24V - unlike industry where you might have significant aux systems. With EVs, you have heat pumps and brake boosters on the auxillary power, so you now have a stronger driver for conversion.
Even within 12V, you'd get a larger weight reduction from not carrying an aux battery, and just feeding through a converter from the HV system.
The 12v battery performs the very significant safety feature of allowing the HV battery to be disconnected when the car isn’t ready to move. You’d need to have a converter in the HV battery to avoid that down side, and then you have a new downside of a fault could cause your 12v line to be HV instead.
Fair point, but I imagine disconnecting is mainly to avoid live HV wiring throughout the vehicle, and thus reducing risk of catastrophic shorts or arcing.
If the aux supply is near or in the battery, leaving that connected would while the rest of HV is interrupted would probably not cause any notable increase in risk.
At the same time, vehicle fires have been caused by a shorted auxillary battery (I have personally experienced an entire industrial building burn down because the 12V battery in a parked ICE car shorted and went up in flames), so I imagine only having one battery to worry about is a risk reduction.
Using a higher voltage is not an innovation (it's an obvious change, and we've gone from 6V to 12V to, in some cases, 24V already) - rather it's just a slight efficiency improvement in largely non-critical systems, with not a lot of incentive to take on the cost of transition.
In a a personal ICE vehicle, the only real significant power was to the starter motor and from the generator, and the distance there was short so the copper didn't really matter and thus no one cared for 24V - unlike industry where you might have significant aux systems. With EVs, you have heat pumps and brake boosters on the auxillary power, so you now have a stronger driver for conversion.
Even within 12V, you'd get a larger weight reduction from not carrying an aux battery, and just feeding through a converter from the HV system.