There is an industry discussion going on about changing vehicle system voltage to 42Vdc. I suspect it is related to a very similar discussion as we have gone thru above.

The issue is simple: the higher the operating voltage the smaller a motor can be to provide the required power output. Don't get side tracked with starter motors: they are not continuous duty rated motors so they can be much smaller. So long as they are allowed to cool as required between operating periods they will last just fine.

It will be interesting to see how this all shakes out. Giving up the room required for the serpentine belt system and radiator fan will allow much more flexibility to reduce the physical size of the engine compartment. This will in turn allow making cars aerodynamic frontal area smaller. Making cars lighter and more aerodynamically clean.

Thus improving fuel mileage ratings. I have long thought that Detroit was well beyond the point of diminishing returns on making engines more "efficient." I put efficient in quotes because the media and other organizations incorrectly interpret miles per gallon as efficiency and use that hammer to drive Detroit to smaller and smaller cars.

Aerodynamics and weight reduction remain as the only choices left to make cars get better fuel mileage. ...And the aerodynamics has done all it can for the moment. Being able to disconnect from the current radiator/fan/belt system in the front will allow a major realignment of the outside of cars and will likely improve the aerodynamics.

 

42? Are you sure it isn't 36 or 48?

Ahh, I see. 36 Volt battery 42 Volt system.

 

36, 42... Don't know the specifics, just some trade literature. Once you go above "low voltage," nominally 30 vdc, it doesn't make alot of difference on the specific voltage.

So then it becomes a decision about size, weight, & capacity.

 

42 because 48 is considered "high voltage" and they'd have to retrain all the technicians.

GM tried to do this several years ago, to no avail. There's just so much automotive infrastructure designed around a 13.8v electrical system.

 

The military uses 24v, surely the big 3 have experience in this area...

 

But most dealer mechanics do not.

Dealership expectations for service revenues drive a LOT of what automakers do, consider the changing of service intervals from 7500 (Prius I) or 10000 (2005 FEH) to 5000 miles...certainly the newer cars are not LESS reliable than their predecessors!

Dealers complain when their highest margin (scheduled maintenance work) revenue declines, and the automakers are forced to change their recommendations to keep them happy. Having to send their entire service staff to electrical school to learn how to be safe around 48 VDC is not something they will like!

 

The reality is that the drive to higher & higher miles per gallon that is being imposed on the automakers will push them into doing away with the large frontal area of the current radiator and auxiliary drive system.

So going to higher voltages helps that problem by making motors smaller, doing away with the serpentine belt system, and putting the radiator somewhere else.

For example, if you can put the power source (motor) and the compressor for the A/C system somewhere else & make it smaller, you free up a lot of real estate inside the engine compartment. Real estate that can be used for many things including a reduction of aerodynamic drag.

 

Yes, I would dearly LOVE to have a Porsche Caymen with a "reversed" Prius drive train. But perhaps with DFI and even a multi-mode engine, Otto/Atkinson/Miller modes. The new Prius engine already transitions from Otto mode into Atkinson mode as the throttle opening rises.

Hmmm...

Wonder if Subaru will soon be producing a hybrid using the B4, "boxer 4" engine concept..??