For years, the chassis of every car has been connected to the battery negative. Changing that would require a re-design of the whole car's wiring system, and probably a lot more copper as every electrical accessory would now need a negative wire.
No need for that - it just needs the on-board 'charger' to provide galvanic isolation between the a.c. supply side and the the vehicle's d.c. side - i.e. what's many conventional SMPSU designs give you anyway. The traction side (usually LV rather than ELV) is usually all copper anyway and the 12V side can continue with its single insulation and chassis return as before.
For years, the chassis of every car has been connected to the battery negative. Changing that would require a re-design of the whole car's wiring system, and probably a lot more copper as every electrical accessory would now need a negative wire.
No need for that - it just needs the on-board 'charger' to provide galvanic isolation between the a.c. supply side and the the vehicle's d.c. side - i.e. what's many conventional SMPSU designs give you anyway. The traction side (usually LV rather than ELV) is usually all copper anyway and the 12V side can continue with its single insulation and chassis return as before.
