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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: 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.

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  • (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.