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To Power the Future, Carmakers Flip on 48-Volt Systems

nytimes.com

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Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#41

Post by mschuster91 »

Gibbon1 wrote: post #12
saltcured wrote: post #6

Earlier quoted context omitted.

You want a higher voltage to allow more power without huge cables due to high current. You want low voltage to avoid high-voltage safety issues which increase engineering, assembly, maintenance, and emergency costs. The 48V system sits right at the boundary where you can deliver enough power for more auxilliary systems and some mild-hybrid techniques including frequent start/stop systems, brief acceleration boost, an…

> Yet, it's not high enough to require switching to a different electrical wiring safety paradigm. This is the tldr. Also once you ditch lead acid batteries for higher voltage hybrid batteries there no reason to keep using 12VDC. The math bit is that the required wire size is related to the inverse square of the voltage. At the same time reduced current means smaller switches.

> Also once you ditch lead acid batteries for higher voltage hybrid batteries there no reason to keep using 12VDC.

Not really. The operating voltages for most of the actual electronic circuits will still be the usual 3V3/5V/12V - and converting from 12V to 5V/3V3 is easier than from 48V.

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#42

Post by ben_w »

nimbius wrote: post #38
csours wrote: post #34

> "But skeptics may wonder why engineers are devoting so much effort to developing the mild hybrid systems that could be seen as stopgap measures on the path to a fully electric vehicle fleet." Let's do some napkin math. Assumptions: 1. Gasoline will never exceed $10/gallon. (assumes eventual plant/algae sourcing/some kind of magic). 1a. Vehicles achieve 50 mpg (2 gallons/ 100 miles) via tricks like 48-volt. Thus fut…

>Gasoline will never exceed $10/gallon. The consequences and repercussions of global warming and climate change plus Nixon era doctrine of interventionalist policy in the interest of maintaining global US oil hegemony have easily put real barrel cost easily above this. Iraq didnt pay for itself twice, after all.

Algae derived oil, if it could be made to work at scale, has none of those problems. It is a not unreasonable upper limit for a totally renewable source of petrochemical fuel.

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#43

Post by jaclaz »

GeorgeTirebiter wrote: post #29
twic wrote: post #11

Earlier quoted context omitted.

The specific number of 48V is presumably inherited from telecommunications: https://electronics.stackexchange.com/questions/10851/why-do... There's lots of telecom equipment that works at 48V, so it's presumably cheap and easy for carmakers to find suppliers.

There is practically no overlap between automotive and telecom. When I was at Tesla, we couldn't find even one manufacturer for common use subsystems (e.g. window motors). It's a chicken and egg problem for now. That's why 'everything' is still at 12V.

Canot say in the US, but in EU most trucks have (since I can remember) 24 V circuits, so there is anyway a long list of parts at 24 V manufactured.

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#44

Post by Theodores »

sowbug wrote: post #3

There is a TLDR for this article, but as far as I can tell it cannot be derived from the article itself. Will someone please explain why 48-volt systems are newly desirable in cars?

I thought the article did a good job of providing examples such as the VW group using 48V to provide 'sportscar' handling in their high end SUV offerings. Having 48V means that these things can be done.

Incidentally VW started out with 6V. Early Beetle and bus models have the joys of 6V electrics, usually replaced for 12V. The advantages are clear. And so it is with the move to 48V.

With turbocharging there is the problem of the wait, by simply using an electric motor then this problem is solved and a smaller engine can be used to deliver the same power and torque. This is not possible on 12V. But it is on 48V.

Stop-start is another area where 48V makes sense. Plus the HVAC.

Why don't Americans have kettles? Because of 110V, you need 240V to boil a kettle properly. Clearly 240V needs proper British Style plugs with convoluted earth arrangements and different wiring. So 48V is the happy compromise where there is no need for excessively regulated voltages. The 48V number is a multiple of 12V therefore four 12V batteries in series will get the desired potential difference.

Much like how we still have older USB ports for keyboards as well as the fancier ones that do power and multiple monitors, there are plans to run the two power levels in the wiring loom. All the lights on the dashboard will run at 12v for now as will the motors in the doors and seats. However, in time those will possibly become 48V too. Sportscars demand theatre with doors that open in cool ways, so imaginably there will be application here for 48V door locks. Imaginably regular VW hatchbacks will have similar 48V based door mechanisms soon with older models still using the 12V cheaper components.

Before these hatchbacks get 48V windows they will probably get the 48V ABS and the 48V power steering along with the 48V stop start.

None of this is a waste of time for companies such as Volvo and how they are engineering their platforms to take any one of many power supplies, hybrid or full electric. Volvo have no future plans for making ICE only vehicles and clearly the market is going towards this smart 48V tech whether the future is full electric or not.

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#45

Post by wazoox »

csours wrote: post #34

> "But skeptics may wonder why engineers are devoting so much effort to developing the mild hybrid systems that could be seen as stopgap measures on the path to a fully electric vehicle fleet." Let's do some napkin math. Assumptions: 1. Gasoline will never exceed $10/gallon. (assumes eventual plant/algae sourcing/some kind of magic). 1a. Vehicles achieve 50 mpg (2 gallons/ 100 miles) via tricks like 48-volt. Thus fut…

In most of Europe, gasoline is already close to 10$/gallon (1.50€/l or more).

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#46

Post by _ph_ »

csours wrote: post #34

> "But skeptics may wonder why engineers are devoting so much effort to developing the mild hybrid systems that could be seen as stopgap measures on the path to a fully electric vehicle fleet." Let's do some napkin math. Assumptions: 1. Gasoline will never exceed $10/gallon. (assumes eventual plant/algae sourcing/some kind of magic). 1a. Vehicles achieve 50 mpg (2 gallons/ 100 miles) via tricks like 48-volt. Thus fut…

The big error in your calculation is, that you calculate only the cost of the battery, but not the cost reduction of removing the most complex parts of a combustion engined car: the engine itself, the gearbox and the whole exhaust system including cleaning. If you calculate this in, you should come up with very different numbers - a lot of experts think, that electic cars might be even cheaper to buy in the early 20ies years.

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#47

Post by _ph_ »

Certainly a nice technology, but I think it is 10 years late. This kind of modernized eletrical design of combustion engined cars which enables mild-hybrids should have been standard 5 years ago. Going forward I cannot see a large future for combustion-engined cars at all - for a few few years, plugin hybrids migth be popular for those, who need a lot of range. But pure electric cars are now coming to the market in numbers. I don't think as stated in the article, that in 2025 only 5% of the vehicles sold will be electric, I would assume that number rather for 2020.

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#48

Post by kev009 »

jaclaz wrote: post #43
GeorgeTirebiter wrote: post #29

Earlier quoted context omitted.

There is practically no overlap between automotive and telecom. When I was at Tesla, we couldn't find even one manufacturer for common use subsystems (e.g. window motors). It's a chicken and egg problem for now. That's why 'everything' is still at 12V.

Canot say in the US, but in EU most trucks have (since I can remember) 24 V circuits, so there is anyway a long list of parts at 24 V manufactured.

All US military vehicles (even COTS ones with civilian counterparts like the CUCV and newer) use 24v. So do most heavy trucks.

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#49

Post by paganel »

_ph_ wrote: post #47

Certainly a nice technology, but I think it is 10 years late. This kind of modernized eletrical design of combustion engined cars which enables mild-hybrids should have been standard 5 years ago. Going forward I cannot see a large future for combustion-engined cars at all - for a few few years, plugin hybrids migth be popular for those, who need a lot of range. But pure electric cars are now coming to the market in n…

2020 is only 2 years from now, we’re nowhere close to that 5% number.

Re: To Power the Future, Carmakers Flip on 48-Volt Systems

#50

Post by _ph_ »

paganel wrote: post #49
_ph_ wrote: post #47

Certainly a nice technology, but I think it is 10 years late. This kind of modernized eletrical design of combustion engined cars which enables mild-hybrids should have been standard 5 years ago. Going forward I cannot see a large future for combustion-engined cars at all - for a few few years, plugin hybrids migth be popular for those, who need a lot of range. But pure electric cars are now coming to the market in n…

2020 is only 2 years from now, we’re nowhere close to that 5% number.

We are already at over 1% EVs in several important markets in 2017, and the EV sales numbers almost double every year, so 2020 probably won't see 5%, but should be pretty close to that - at least closer than 2025.
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