Featured Automotive 12v vs 48v Architecture ?

when is tesla switching all their vehicles?

 

You said "the benefits are extensive" but what are the benefits other than making power wires slightly smaller gauge? The article didn't have any more information. It seems like this change would only be worth a few pounds per vehicle.

 

Lighter electric motors too, for steering and such.

 

About the time I replace my 12V buss, 2019 Model 3. <GRINS>

Bob Wilson

 

That only applies to a couple of small motors on the car though - steering, HVAC, the battery fan, etc. Maybe the brake booster, I imagine that is run on low voltage, but I'm not really sure. We are probably talking about a pound or two per vehicle. All the powertrain MG units won't be affected. And the inverter wouldn't be any different.

 

Right, but it's only a few pounds of some of the most expensive materials in the car. Times hundreds of millions of cars.

 

I have a vague memory that some Toyota vehicles with electric-motor power steering are already running it from its own DC/DC converter at 48 volts, but I don't remember which ones or where I saw it, so grain of salt. That motor needs to have some serious grunt.

 

Copper wires are definitely not anywhere close to the most expensive materials in the car. Probably not even in the top ten.

Compared with designing hundreds of new standard sizes and configurations for batteries, changing around the whole supply chain, retooling battery factories all over the world, phasing these new batteries and cars and alternators in over many years (since cars that need 12v batteries will still be around in 20-30 years) etc., and getting all of the automotive manufacturers to agree to that - which they won't, so you will need multiple standards for the same thing for many years. All so we can use a little bit less of highly-recyclable, and highly-recycled copper (a commodity, not a precious or rare metal).

I would believe that. We have a Mazda with electric power steering, and I assume it is just 12 volts because it's a pretty simple car, but it does have an 80 amp fuse for the power steering.

 

The old GM 'mild' hybrids used a 48 V power system.

Bob Wilson

 

In a traditional vehicle the advantages are slight. In a vehicle that uses a lot of power like electronic AC, water pumps, electronic power steering, other power electronics like electronic turbo or super chargers, there are advantages to those parts. It does require volume of the other 12V parts. Because of safety concerns a 48V hybrid might be significantly less expensive, with higher voltages for plugins.

 

It's another way to exclusive limited supply parts that will be more expensive than widely available generic 12 volt parts.

48 volt cables would require more complex shielding from 5 volt digital devices used in computer control modules that can be fried more readily "fried" when coming in contact with voltages.

That has cause devastating results that have cost loss of life in commercial aircraft accidents.

 

This would create a large market for 48V to 12V DC buck converters.

JeffD

 

Be prepared to pay $400 for a replacement starter battery. We all complain about paying $200 for a battery for the Prius that most of us here own.

 

Does 48v DC really need to be shielded from DC any more than 12v currently is? It's still DC just lower amps, seems like it would require less care if anything.

 

I guess I look at a finished wiring harness as considerably more valuable than its constituent copper, by the pound anyway.

 

The copper's the only constituent there'd be less of. The rest is all insulation and chafe protection and terminals and connectors.

They already minimize the copper as much as they can, by using the crazy thin high temperature automotive insulation, allowing angel-hair-thickness wires that would horrify any electrician used to 90℃ house wiring.

At 48 V they could make the copper even thinner ... but they might have to make the insulation 4✕ thicker.

 

Rats will get a kick out of it if the insulation is soy based. Sparks at 48 volts would more likely cause fires.