Why haven't we moved to higher DC voltages?

[LoganD]

They don't re-engineer everything to that extreme of a degree, though. There's always going to be legacy hardware.

At any rate, this isn't the kind of engineering I'm talking about. I mean the type of things they would have to do to ensure that absolutely nothing from a low voltage system is used in a high voltage system. Especially as it would be prohibitively expensive to do a 100% roll-in, so there would be legacy systems in place that would have to run on their own separate buses.

I can't think of a single vehicle made that started life 100% fresh, with no shared components with other or previous models. That's the sort of thing that would have to happen with a voltage change. It was not terribly difficult in the 50s and such, when you had negligible electrical components and the "electronics" was your kid's ham radio riding in the back seat.

There's already cars with 48V systems in production. This is not theoretical.

You underestimate how thoroughly everything is re-engineered with every new vehicle platform. There is almost nothing that is carried over when a platform is changed.

In the field, I'm not seeing that. There is a lot of carryover both between designs and carried forward into replacement designs. Design inertia is a thing because clean sheets are prohibitively expensive, and there is usually no positive value in new for the sake of new.


If anyone was going to do it, I'd wager it to be a smaller car company that contracts out everything electronic to a single supplier like Bosch or Hitachi. (Probably Bosch, Hitachi is a follower not a leader)

I do hope you don't think I am being combative! I ask questions because I want to understand rationale. Having to throw away a lot of legacy items like bulbs is a huge thing. And on the technician side, having to get 48v capable scantools would be a huge expense. As much as people hated OBD-II twenty-plus years ago, having a single standardized DLC is a huge cost saver.

Everything is changing right now. Cars have changed so much in the last 5 years, and it's accelerating. The systems and electronics on a vehicle from 2024 will be unrecognizable to a vehicle from 2014.

[j-c-c]

I believe the use of "shock" is rather subjective here. Accidentally shorting out the terminals on a fully charged Group 24 battery will "shock" anyone nearby, with noise, surprise, light flash, heat,etc, that they will not care much about whether they actually conducted any electrons thru their body. Regarding higher voltages, the actual real power is still W*V. The NEC (a 100+ year old constantly revised National electrical code mainly written for safety) I believe in the past was mainly focused on lethality, not shock, and it was many decades felt the human body's natural resistance to a lethal shock was 77 Volts. It might have been slightly arbitrary, but they had to pick a number. Which was the reason installed sound systems could be wired at up to 70 Volts, and not require NEC regulations. I believe that 77 volt number still has lot of merit.

Everyone knows a 9V battery on your tongue will get your attention, but that's it. I have decades of experience with 20-24G wiring in audio end of the concert business, which has high needs for reliability, and the cabling is often abused in many ways, night after night. The cases of simple wire failure are almost non existent. Connector/connection failure is the usual culprit and that is also rare when properly designed/assemble.

Only real 'downside" of merit I have read above for not moving beyond 12V today, in a few years, the 12V/ICE will be a museum piece, it seems anyway.

This could have been an improvement say 12? years ago.

[Greenlight]

I worked for an OEM in R&D for a few years. We worked on the 36V & 42V systems for a while in 1999~2003. One of the big problems we faced was arcing in switches, causing them to NOT meet the durability specifications. Other suppliers (AC, window regulator, radio,...…) reported problems as well. There were also EMF issues that were not present in the 12v systems.

Of course the problems could be fixed, but for a price. And in automotive, adding a few dollars to the price of a car is a big deal.

The overall cost/benefit was not conducive with proceeding at the time.

As far as I know they have revisited this issue and there may by high voltage systems in the near future.

[Rick!]

I've been waiting for this 48volt event since last century and it still isn't mainstream.

The only items I see benefiting from the higher voltage are PWMs and electromechanical solenoids and anything using MRF. Response times go way down and theoretical performance goes up since now there is more opportunity to measure, predict, respond per event. But if I can't create ride "goodness" a customer can feel and then wants to pay more for it, that's not winning.

I learned long ago that if the change doesn't increase profits or sell more vehicles that it's not going to get funded. It seems the 48 volt push has fallen into the 'not getting funded' bucket for most OEMs. From what some others are saying here, the tech has not been matured yet which means it's not on the shelf to be implemented. During a vehicle project is not the place to develop technology as it's really hard to insert "development breakthrough" into the Gantt chart timeline.

[Zmechanic]

I believe the use of "shock" is rather subjective here. Accidentally shorting out the terminals on a fully charged Group 24 battery will "shock" anyone nearby, with noise, surprise, light flash, heat,etc, that they will not care much about whether they actually conducted any electrons thru their body. Regarding higher voltages, the actual real power is still W*V. The NEC (a 100+ year old constantly revised National electrical code mainly written for safety) I believe in the past was mainly focused on lethality, not shock, and it was many decades felt the human body's natural resistance to a lethal shock was 77 Volts. It might have been slightly arbitrary, but they had to pick a number. Which was the reason installed sound systems could be wired at up to 70 Volts, and not require NEC regulations. I believe that 77 volt number still has lot of merit.

Everyone knows a 9V battery on your tongue will get your attention, but that's it. I have decades of experience with 20-24G wiring in audio end of the concert business, which has high needs for reliability, and the cabling is often abused in many ways, night after night. The cases of simple wire failure are almost non existent. Connector/connection failure is the usual culprit and that is also rare when properly designed/assemble.

Only real 'downside" of merit I have read above for not moving beyond 12V today, in a few years, the 12V/ICE will be a museum piece, it seems anyway.

This could have been an improvement say 12? years ago.

Anything over 60VDC (static) or 42Vpk alternating is generally consider hazardous voltage in DRY installation. It drops to 35VDC and 24Vpk alternating in wet conditions. That's according to UL and IEC standards.

[j-c-c]

Interesting, I suspect over time the "V" thresholds have lowered, as more lawyers arrive.
I also wonder if the "35" was chosen intentionally as if they had chosen say "11" as the threshold.
Somebody wants this idea to go away?

Somebody should have caught my blatant/stupid "w*V" miss type.

[gruntguru]

Turn the question around: What are the advantages of higher voltage?. . . . .

. . . . So, again, what are the advantages that would justify having to re-engineer literally every component in a given car?

Mild hybrid will drive the change.