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posted by Fnord666 on Monday February 26 2018, @12:12AM   Printer-friendly
from the shocking-news dept.

Car companies, starting with Volvo last summer, have laid out plans to electrify entire lineups of vehicles. But the fine print makes it clear that the coming decade and beyond will focus not just on massive battery packs powering electric motors, but also on adding a little extra juice to the venerable internal combustion engine.

Increasingly, that juice will arrive in the form of new electrical systems built to a 48-volt standard, instead of the 12-volt systems that have dominated since the 1950s. Simpler than Prius-type drivetrains and less expensive than Tesla-scale battery power, the new electrical architecture both satisfies the demands of cars made more power hungry by their gadget load and enables the use of lower-cost hybrid drive systems.

https://www.nytimes.com/2018/02/08/business/electric-cars-48-volts.html


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  • (Score: 1, Insightful) by Anonymous Coward on Monday February 26 2018, @02:28AM (20 children)

    by Anonymous Coward on Monday February 26 2018, @02:28AM (#643694)

    what LED runs on 48 volts?
    might as well move to HPS cabin lights

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  • (Score: 5, Informative) by requerdanos on Monday February 26 2018, @02:39AM (6 children)

    by requerdanos (5997) Subscriber Badge on Monday February 26 2018, @02:39AM (#643699) Journal

    what LED runs on 48 volts?

    The selection of 48 volt LEDs is just as expansive as that of 12 volt LEDs: None.

    We use resistors, LEDs in series, and other various tricks to run low voltage lighting on higher voltage supplies.

    • (Score: 2) by fyngyrz on Monday February 26 2018, @03:02AM

      by fyngyrz (6567) on Monday February 26 2018, @03:02AM (#643716) Journal

      The selection of 48 volt LEDs is just as expansive as that of 12 volt LEDs: None.

      That is irrelevant to the point that 12v filaments are more physically robust than 48v filaments.

      And given that, such electrical "tricks" to make LEDs work in a 48v environment are easy, robust, and long-term dependable; much more so than heated filaments — of any kind.

    • (Score: 2, Informative) by anubi on Monday February 26 2018, @06:41AM (4 children)

      by anubi (2828) on Monday February 26 2018, @06:41AM (#643797) Journal

      Well, the 100-Watt LED chip arrays normally run on around 32-34 Volts.

      The 10-Watt LED chip arrays I have seen run on around 10 volts, although I have a couple that also want to see about 30 volts.

      The voltages are predicated on each blue ( white if phosphored ) LED chips having a Vf of about three volts.

      Its customary to current-drive these, not voltage drive them. Their current/voltage curve is extremely nonlinear.

      Its like trying to drive a zener diode. Except some of the energy dissipated is released as light instead of heat.

      So most people involve a current-mode SwitchMode Power Switcher design. Turns out the LED, needing constant current, is an ideal match for the current-mode switching designs, that optimally power a constant current load.

      So what voltage you have to start off with is really a tiny consideration. Many designs are extremely tolerant of quite wide input voltage range.

      We have made some extremely clever innovations in SwitchMode power conversion in the last 30 years or so. We can convert DC from one form to another just about as easily as a gearbox handles RPM/Torque tradeoffs.

      At this point, I just hope they go ahead and ditch lead-acid car battery technologies... as unmonitored series cells are trouble prone due to slight variations in cell current leakages, which forces the "better" cells in the series stack to accept overcharge as the charger tries to top off the laggards. And, of course, the stronger cells in a series stack will cause severe damage to the weaker ones as the whole bank nears discharge, and the stronger cells will actually ram current backwards through the weaker cells that pooped out first.

      Here's hoping the newer 48 volt car batteries will be lithium smart-batteries with the proper charge balancing and cell monitoring, and hopefully standardize on a public interface.... personally I would love to see them interface as an isolated SPI. So I would get serial clock and data ( incoming and outgoing ) data, and a "Yes, I am talking to You" Chip Select line. So we can use them for many other things besides cars.

      If I had my druthers, I would have the batteries protection circuitry disable the connection to the power terminals ( via biasing of MOSFET switches ) until the SPI port has been talked to and told to turn it on.... and continued SPI to keep it on... as when we start talking this much energy stored with this kind of release rate, its kinda like wanting to keep gasoline in the proper container as well. If the energy is released without control, bad things are likely to happen.

      If its a well-known public interface, even Arduinos can talk to it. Gotta have power switches anyway. Might as well use the one in the battery.

      Bikes, toys, boats, and solar storage comes to mind, others will follow.

      --
      "Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
      • (Score: 2, Insightful) by Anonymous Coward on Monday February 26 2018, @09:00AM (1 child)

        by Anonymous Coward on Monday February 26 2018, @09:00AM (#643833)

        Here's hoping the newer 48 volt car batteries will be lithium

        How to lithium batteries handle the kind of abuse that car batteries need to withstand?

        - Cranking the starter, hearing the RPMs drop because the battery is close to empty, and just as the RPMs are dropping too low, the engine springs to life.

        - Being outside of the winter, slowly losing charge, until there isn't enough power to even blink the alarm diode, before someone finally gets around to find a 300 foot extension cord (not everyone can have their apartment next to the parking lot) and put a charger on it.

        I know phone lithium batteries tend to die at just the thought of that kind of abuse. They really don't like to go below 40% charge, especially not for a long time.

        And no, putting electronic restrictions in that prevent one from starting the car only means that people will be unable to get to work, which will be the number one thing to stop your idea if anyone tries it.

        • (Score: 2) by toddestan on Tuesday February 27 2018, @03:20AM

          by toddestan (4982) on Tuesday February 27 2018, @03:20AM (#644441)

          I got 13 years out of my last car's battery. And that is in a northern climate too. Battery still worked when I replaced it, though it was getting kind of obvious that the end was approaching. Given my experience with lithium ion batteries, I'd be surprised if one would last half as long.

          Yes, I know Tesla expects their batteries to last longer, but they've also engineered their batteries packs with heating/cooling and normally don't let them go the extremes on the charge/discharge range. The battery in my car sits unprotected in the engine compartment is is basically exposed to the elements.

      • (Score: 2) by Grishnakh on Monday February 26 2018, @10:12PM

        by Grishnakh (2831) on Monday February 26 2018, @10:12PM (#644247)

        Well, the 100-Watt LED chip arrays normally run on around 32-34 Volts.

        So what voltage you have to start off with is really a tiny consideration. Many designs are extremely tolerant of quite wide input voltage range.
        We have made some extremely clever innovations in SwitchMode power conversion in the last 30 years or so. We can convert DC from one form to another just about as easily as a gearbox handles RPM/Torque tradeoffs.

        Yes, that's the whole point. You don't need 12V to drive LEDs, since you're going to use a SMPS to drive the LEDs no matter what the vehicle supply voltage is. So you'll just redesign your LED drive circuit to use a ~48V supply instead of a ~12V one. The problem is all these crazy posters here who seem to think we're going to have big 48V-12V converters in cars for several decades to power everything electronic, because they can't seem to understand the idea that electrical devices in the car will simply be driven directly with 48V when cars start coming with such systems.

      • (Score: 2) by requerdanos on Monday February 26 2018, @10:17PM

        by requerdanos (5997) Subscriber Badge on Monday February 26 2018, @10:17PM (#644252) Journal

        Here's hoping the newer 48 volt car batteries will... standardize on a public interface.... personally I would love to see them interface as an isolated SPI. So I would get serial clock and data ( incoming and outgoing ) data, and a "Yes, I am talking to You" Chip Select line.... If I had my druthers,

        Well, "Tesla", probably one of the leading companies in the new-type-of-car-battery business, uses DRM and forced software updates [theregister.co.uk] to manage their batteries (Note: not "your" batteries, even if you ostensibly "own" them). Even worse, when last it was discussed here, lots of users of this site argued that Tesla had the right to do whatever they want with batteries they manufactured (but don't own) and they only had the consumers' best interests at heart. (Users of this site!)

        So it's not looking good for your best-and-safest-for-everyone proposal, which I would submit has very little chance of surviving what could arguably called the prevailing Apple-Microsoft-DRM mindset. You are much more likely to have to phone the (contract call center for the) company that manages "your" 48 volt battery, talk your way up to at least level 2 support, and then ask nicely what they can read of your battery's characteristics.

  • (Score: 3, Insightful) by Grishnakh on Monday February 26 2018, @02:44AM (12 children)

    by Grishnakh (2831) on Monday February 26 2018, @02:44AM (#643703)

    What LEDs run on 12V? Answer: none of them. LEDs operate on less than 1V. To make them useful on any normal power supply (12VDC, 110VAC, etc.), you either need to use a voltage regulator circuit, or as a quick hack, daisy-chain a bunch of them in series and then add a dropping resistor. The latter is pretty crappy in a car because the voltage fluctuates so much and can have significant spikes (which you can deal with using a TVS suppressor).

    • (Score: 2) by fyngyrz on Monday February 26 2018, @03:04AM (7 children)

      by fyngyrz (6567) on Monday February 26 2018, @03:04AM (#643718) Journal

      What LEDs run on 12V? Answer: none of them.

      Switching voltage regulators are very efficient and can provide the voltage conversions required. It's really not a problem at all.

      • (Score: 5, Informative) by Grishnakh on Monday February 26 2018, @03:52AM (6 children)

        by Grishnakh (2831) on Monday February 26 2018, @03:52AM (#643739)

        Exactly my point.

        The only downside with lighting for moving to 48V is that you wouldn't be able to use off-the-shelf parts already in your supply chain; you'd have to get your suppliers to make new 48V parts instead. But once that's done, it's no big deal. Automakers have to get lots of parts redesigned or modified for new generations of cars anyway. If you're doing a fresh design of, for instance, an LED/DRL headlight assembly, it's no more work to make it 48V than 12V. Honestly I'm surprised they haven't bothered with this sooner, though the fairly recent move to changing everything to LEDs might have changed the equation (making new standards for incandescent bulbs isn't so easy; with LEDs you don't care because they're all built-in): with 48V, you can reduce the wiring size significantly, saving some weight and also saving a lot of copper, which is expensive. They stand to save a bunch of money per car just by reducing copper wiring, and probably more by reducing motor sizes (again, reducing copper).

        • (Score: 2) by fyngyrz on Monday February 26 2018, @06:16AM (5 children)

          by fyngyrz (6567) on Monday February 26 2018, @06:16AM (#643786) Journal

          They can also move the power supplies out of the LEDs; one common source for various E and I needs would be much more cost effective. No reason 12v devices wouldn't still be in the loop, either – the current crop of entertainment systems, for instance.

          The important stuff here, as you note, is the motors. Between those and environmental control systems, there's the potential serious efficiency gain.

          • (Score: 2) by Grishnakh on Monday February 26 2018, @09:17PM (4 children)

            by Grishnakh (2831) on Monday February 26 2018, @09:17PM (#644204)

            Why would you need 12V for infotainment? Infotainment systems are electronic, so they run on something like 3.3V, not 12V, and perhaps some other odd voltage for the LCD panel, and probably something else odd (and higher than 12V) for the audio amplifiers. When a new generation of cars with 48V buses is designed, the new generation of infotainment will simply be designed to use a 48V supply. The audio amplifier engineers will probably be happy about that too.

            • (Score: 2) by fyngyrz on Tuesday February 27 2018, @02:21PM (3 children)

              by fyngyrz (6567) on Tuesday February 27 2018, @02:21PM (#644618) Journal

              Why would you need 12V for infotainment?

              Two reasons: That's the tech that's typical, so it's painless; and power amplifiers like 12v. They would like 48v even better, but again, that tends to obsolete a bunch of already existing power amp design.

              When a new generation of cars with 48V buses is designed, the new generation of infotainment will simply be designed to use a 48V supply. The audio amplifier engineers will probably be happy about that too.

              Perhaps. Or perhaps 48v will fall flat on its face, like 6v power systems have. We will see.

              • (Score: 2) by Grishnakh on Tuesday February 27 2018, @04:54PM (2 children)

                by Grishnakh (2831) on Tuesday February 27 2018, @04:54PM (#644671)

                That's the tech that's typical, so it's painless

                No, it's not. No infotainment system runs on 12V internally; modern electronics all run at 3.3V these days. And there's no such thing as "typical" in infotainment, as there's nothing that's off-the-shelf: every system is custom-designed for that automaker. With a new generation of cars using a new 48V bus and a new generation of infotainment systems, they'll just design the infotainment to run from a 48V external supply.

                and power amplifiers like 12v

                No, they don't. Every decent audio amp used in cars uses a DC-to-DC converter to boost the supply voltage.

                that tends to obsolete a bunch of already existing power amp design.

                No, it just means they need to slightly redesign their DC-DC converter. Power amps in cars are, much like infotainment systems, made custom for that vehicle to an extent. Toyota doesn't go to Best Buy and purchase Kenwood amps off the shelf.

                Or perhaps 48v will fall flat on its face, like 6v power systems have.

                Huh? 6V systems did no such thing; they were somewhat common in cars ages ago. They came *before* the push to standardize on 12V, so "falling flat on their face" doesn't make any sense in this context, as 6V was never pushed as a successor. There *was* a push a couple decades ago to move to 36V, and that one *did* fall flat on its face, unfortunately.

                But you're right, it's quite possible. After all, with electric cars looking like they're going to be the norm in a decade, those have battery voltages well above 48V (I think the LEAF is at 380V??). However, there's a lot of motors and electronics in cars these days and it's getting worse, so there's some gains to be made in efficiency with a higher voltage bus for things other than the traction motor, and you don't want to run your window motors and infotainment at 380V (you could, but it's much more dangerous and there's new issues with insulation due to the high voltage).

                • (Score: 2) by fyngyrz on Tuesday February 27 2018, @05:50PM (1 child)

                  by fyngyrz (6567) on Tuesday February 27 2018, @05:50PM (#644706) Journal

                  No, it's not. No infotainment system runs on 12V internally; modern electronics all run at 3.3V these days.

                  ...converted from the 12v using the existing internal design. If the vehicle produces a usable 12v (well, 12.6...14.5 as per usual) supply, then a redesign is not required. And entertainment systems are just the tip of the iceberg. GPSs, camera systems, ham radio gear, CBs, IR systems, light bars... you get the idea. They're all 12v. Likely there will be significant pressure to keep them that way, or everyone has to redesign. Redesign costs money. Not to mention that the new 48v-only vehicle won't be compatible with 99.99% of what's out there from the start, and that's hardly a selling point.

                  Every decent audio amp used in cars uses a DC-to-DC converter to boost the supply voltage.

                  ...which again, is part of the existing internal design. Redesign costs money. New PCBs; new RF shielding or alteration to same; new FCC testing; new performance testing and validation; component validation for the extreme temperature ranges under operating conditions; component warehousing, acquisition, and assembly automation or training; complete rejiggering of manufacturing costs; marketing; etc. I did this stuff for a living for decades. There's no "it's easy" in this domain.

                  That's not even counting the car installer, etc., who might try to keep both kinds of systems in stock for the two types of power systems; that's quite an economic blow. I'm thinking your 48v devices are going to be a special order, assuming they want to deal with them at all.

                  6V systems did no such thing; they were somewhat common in cars ages ago.

                  ...and now they are not. Or IOW, just as I said, 6v vehicle systems have fallen on their collective face. This is, of course, because higher voltages make for higher efficiencies for most major clients of vehicular power consumption. Which is why 48v might get in there; but I think it's still very likely that these 48v systems will generate 12-ish volts to support the huge constellation of power clients that currently require that as an input supply; and given that they do provide such a supply, there's no motivation to change anything else very quickly.

                  • (Score: 2) by Grishnakh on Tuesday February 27 2018, @07:18PM

                    by Grishnakh (2831) on Tuesday February 27 2018, @07:18PM (#644742)

                    And entertainment systems are just the tip of the iceberg. GPSs, camera systems, ham radio gear, CBs, IR systems, light bars... you get the idea. They're all 12v.

                    Ham radios, CDs, and light bars are not standard equipment on any passenger car. Automakers don't design their cars for aftermarket equipment. The most you're going to see is 48V-to-12V converters for lighter sockets, since people do use accessories that plug into those and will demand working lighter sockets in new vehicles. Ham radios, I believe, are too high-power to run off standard lighter sockets (which can only supply 5A/60W in many cars), so those will need some additional converter ($$). But automakers really don't care about the puny number of hams on the road. And from what I've seen of hams, they always drive shitty old cars anyway, not brand-new ones. The only people who still use CB these days are truckers.

                    Redesign costs money.

                    They're redesigning many things with every new vehicle generation anyway. They don't keep using the same infotainment system across 3 generations.

                    ...which again, is part of the existing internal design. Redesign costs money. New PCBs; new RF shielding or alteration to same; new FCC testing; new performance testing and validation; component validation for the extreme temperature ranges under operating conditions; component warehousing, acquisition, and assembly automation or training; complete rejiggering of manufacturing costs; marketing; etc. I did this stuff for a living for decades.

                    And yet you seem to think they're going to keep using the same electronics design for 20 years. I don't care what you did for decades, I know full well that vehicle electronics routinely change with every vehicle generation, which is 3-6 years.

                    That's not even counting the car installer, etc., who might try to keep both kinds of systems in stock for the two types of power systems; that's quite an economic blow. I'm thinking your 48v devices are going to be a special order, assuming they want to deal with them at all.

                    Automakers do not care what "installers" do, or what anyone in the aftermarket does, for the most part. They sure as hell don't design their cars for audio enthusiasts who intend to install custom stereos. The aftermarket goes wherever the automakers go; if they switch to 48V systems, the aftermarket will be forced to follow.

                    Or IOW, just as I said, 6v vehicle systems have fallen on their collective face.

                    I'm sorry, this is just plain silly. That's like claiming that the landline telephone "fell on its face". "Fell on its face" means that something was a flop: it was attempted, but failed, such as a Hollywood movie that costs $100M and then nets $5M. Landline phones did not fail; they were enormously successful for many, many decades, until recent years where cellphones have become very popular. From what I've read, 6V cars were somewhat common at one time long ago, they simply became obsolete, just like 4-wheel drum brakes and manual-crank windows.

    • (Score: 1, Informative) by Anonymous Coward on Monday February 26 2018, @04:33AM (3 children)

      by Anonymous Coward on Monday February 26 2018, @04:33AM (#643762)

      LEDs operate on less than 1V

      Most LEDs won't run on 1V. It obviously depends on the part but many need 2V or more to operate.

      The voltage drop usually depends on several factors, including temperature and operating current. LED manufacturers publish graphs that show how this works. See the datasheet for your specific part.

      • (Score: 2) by Grishnakh on Monday February 26 2018, @09:21PM (2 children)

        by Grishnakh (2831) on Monday February 26 2018, @09:21PM (#644207)

        Depends on the LED. If you're talking about a simple indicator LED, those are usually 0.7-1V. The ultra-high-brightness ones are probably a little higher, but I've never heard of any diode that had a 2V Vf rating.

        • (Score: 1, Informative) by Anonymous Coward on Monday February 26 2018, @11:16PM (1 child)

          by Anonymous Coward on Monday February 26 2018, @11:16PM (#644297)

          If you're talking about a simple indicator LED, those are usually 0.7-1V. The ultra-high-brightness ones are probably a little higher, but I've never heard of any diode that had a 2V Vf rating.

          Then you have not looked at many LEDs. A 0.7V indicator LED would be a highly specialized part. Where did you even find such a thing? Can you identify even one currently-available part with less than or equal to 1V Vf typical?

          We can use digikey search filters to get a general feel for what's available in their catalogue. Under the "LED Indication - Discrete" category, they list, based on Vf (typical):

          • 1.2V: 1 part listed (this is the lowest typical Vf in the entire catalogue, and it is a non-stocked item to boot)
          • (zero parts listed between 1.2V and 1.6V)
          • 1.6–1.69V: 84 parts listed
          • 1.7–1.79V: 393 parts listed
          • 1.8–1.89V: 986 parts listed
          • 1.9–1.99V: 1774 parts listed
          • 2.0–2.09V: 5434 parts listed
          • 2.1–2.19V: 3827 parts listed
          • 2.2–2.29V: 2366 parts listed
          • 2.3–2.39V: 308 parts listed

          etc. (The catalogue keeps going all the way up to 14V Vf typical). Note that the numbers include duplicates, e.g., the same component in various kinds of packaging.

          These are indicators so not the same type of LED used for lighting purposes. For that, this is a typical part that could be used for lighting purposes [digikey.ca]: note the Vf typical of 2.95V -- much higher than 0.7V!

          • (Score: 0) by Anonymous Coward on Monday February 26 2018, @11:37PM

            by Anonymous Coward on Monday February 26 2018, @11:37PM (#644307)

            Note that at the Vf (typical) represents the voltage at some fixed operating current. With a lower current the LED will probably operate at a lower voltage... to a point. Sometimes this information is in the datasheet. If you care about your product yields, it is best to ensure your LED driver circuit can supply at least what is specified for your part.