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42-Volt Autos 619

Posted by michael
from the more-power dept.
brianlmoon writes "Car Audio Electronics Magazine has a story about the auto industry switching to 36/42-Volt systems starting in 2004 and being completely switched by 2020. The demand for luxuries in cars has grown to where 12/14-Volts is just simply not enough. The automotive sound enthusiasts are going to benefit greatly as amplification will be much easier and cleaner with 3 times the voltage availble. Mobile computing will also benefit: "One of the real benefits of jumping to 42-volt systems, especially for hybrid vehicles, is the ability of the vehicle to offer regular 110-volt electrical outlets". It seems cars will have dual systems for a while for legacy equipment."
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42-Volt Autos

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  • Oh great (Score:2, Interesting)

    by ArchieBunker (132337)
    Can't wait to see what these new batteries are going to cost...

  • Wow! (Score:2, Redundant)

    by jeffkjo1 (663413)
    This news is positively shocking!
  • Bastards! (Score:3, Funny)

    by Anonymous Coward on Sunday June 15, 2003 @01:41PM (#6205059)
    If they had chosen -56/48 VDC systems, cars would be compatible with Telco systems.
  • by nurb432 (527695) on Sunday June 15, 2003 @01:41PM (#6205062) Homepage Journal
    I remember hearing that from a commercial back in the early 50's...

    Never create an artificial ceiling.. as it will be exceeded.. always.

  • More accidents? (Score:5, Insightful)

    by roryh (141204) on Sunday June 15, 2003 @01:42PM (#6205069) Homepage
    Most car drivers I see don't pay enough attention on the road as it is, and that's without the ability to plug in household applicances. Multi-car pileups because someone was checking their email or pr0n?
    • by moofdaddy (570503) on Sunday June 15, 2003 @01:49PM (#6205108) Homepage
      The day I see someone making a smoothy as they drive down rt. 95 is the day I stop driving.
      • My aunt and uncle were driving on one of the major highways in Toronto (the 401, I think) and saw a car weaving back and forth in its own--and adjacent--lanes.

        While (very carefully) passing this car, they observed the driver knitting.

  • by reiggin (646111) on Sunday June 15, 2003 @01:43PM (#6205073)
    Does this mean if my new car has a 42v system and the car battery dies and leaves me stranded out in BFE, I have to wait for another 42v car to come by before I can get a jump? That would suck.
    • by Drakin (415182) on Sunday June 15, 2003 @01:54PM (#6205138)
      Naw, just flag down 3 12 volt cars to give you a boost...
    • by Stigmata669 (517894) on Sunday June 15, 2003 @01:55PM (#6205147)
      No, you just need to jump start your car with 4 friends in parallel. I see a whole new brand of MONSTER(tm) jumper cables coming on.
    • No, you just need three and a half regular cars and some extra jumper cables.
    • by s20451 (410424) on Sunday June 15, 2003 @02:07PM (#6205241) Journal
      Yes, you would be screwed if you had to charge a 42v battery from one 12v. Even four 12v in series might be a problem; the extra (48-42)=6v load would be dissipated in the battery, and shorting a few volts across a battery might not be good for it.

      If the car companies had any brains, they would anticipate this problem. They could put some electronic thingy on the charging posts that automatically senses 12v and runs it through some power electronics to step it up to 42v. I don't know how efficient that would be.

      Or, if the engine electrical system still runs on 12v (through a step-down), there could be a direct interface to the starter -- once the engine is started, the alternator takes over and charges the battery at 42v.

      On the other hand, they could just go with the inelegant solution of designing an interface that makes it impossible to connect jumper cables. Then you would be in trouble.
      • On the other hand, they could just go with the inelegant solution of designing an interface that makes it impossible to connect jumper cables.

        We had to boost one of our cars the other day, and the only other vehicle handy was my father's Montana. The battery is in there in such a way that you cannot access the terminals directly, at least not without cutting away parts of the frame (or removing the battery, of course). To allow for boosts TO the van, they have a 'remote positive terminal' which you can
        • by Jboy_24 (88864) on Sunday June 15, 2003 @03:58PM (#6206002) Homepage
          You should NEVER use both the positive and negative terminal's from a battery for boosting. Basically by doing this your essentially flicking a lighter by a source of hydrogen (the battery). When you make the final connection between batteries there is ALWAYS a large amount of sparks. Batteries product hydrogen and in some cases will explode if you provide a spark near them. This has the handy side-effect of showering everyone near by with large amounts of Sulfuric acid.

          The WAY you should boost a car is to connect positive battery terminal to positve battery terminal, then connect the negative to a part of the frame where there is no paint and you can get a good connection, away from the battery compartment.

          If you absolutly must connect to the negative terminal (can't find a good ground), connect the most dangerous negative terminal first (most enclosed space, less water in battery etc). That way there will be no sparks near the dangerous battery.

      • Why higher voltages? The higher the voltage, the lower the current (amps).

        Losses are mostly related to the number of amps. So, given that you have a 12V battery, and require about 1.2 kW for the starter motor, you need about 100 amps. That requires hefty cables.

        At 42V, that same 1.2kW starter motor requires only 29 amps.

        If you want to be able to plug in an "old fashioned" 12V radio, a local step-down converter can be had pretty cheaply, and can convert 42 to 12 without trouble. This works the same way as
    • Early 36/42 Volt systems will usually be dual 12/36 Volt systems, as they haven't solved all the problems with things like headlights, which work quite a bit better at 12 Volts than at 42(High current is good, you can have a thicker filament, which is more durable). In addition to those with a 12 Volt system, early pure 42 Volt cars will likely have a converter that you can use to start off of a 12 volt car, or I think, help start a 12 volt car. The interesting stuff is in the steer by wire and electric bra
      • they haven't solved all the problems with things like headlights, which work quite a bit better at 12 Volts than at 42

        My guess is that most 36/42 volt cars will have xenon-arc HID lamps. The retail cost on those has gone from $5K - $500 in a very short period of time and will probably keep dropping. A typical Kia may never have HIDs, but most cars probably will. Now if only folks will keep their damned lenses clean and reflectors balanced to cut down on the glare!

        There are a lot of other parts that will
  • by MosesJones (55544) on Sunday June 15, 2003 @01:44PM (#6205077) Homepage

    Sure it mentions Hybrids in there but we all know that it is the "luxury" cars driving these changes, larger power-supplies will require more power to charge, which in turn requires more fuel.

    So excuse me if I don't "welcome" this so someone can have an even louder stereo while pumping even more chemicals into the atmosphere. So we can have 110v power supplies so... so what ? So a "busy exec" can have an even large mobile office ? So Ted and Rhona in the back can have a Playstation 2 each ?

    I would say that goverments should be introducing regulations to reduce fuel emissions... but somehow in the country where this will be plonked into Canyenero style SUVs I doubt that the Oil President will concern himself with more fuel being used.
    • And what do you drive?
      • A Train... (Score:3, Funny)

        by MosesJones (55544)

        Except I don't drive it, I have a chauffer who does it for me, there are also lots of other people who share the same chauffer :-)
    • don't worry....in a bout 10 years we should be recycling all our carbon so the crap we put in the air will eventualy get put back into the cars.

      http://www.discover.com/may_03/featoil.html
    • It depends on how many hungry things are hooked up, not how much voltage the battery has.

      A higher voltage on the line is a good thing because it means less current through the wires, which in turn means less losses across them. Oh, and less current through the entire system means it is easier to keep a proper ground level across the entire chassis.

    • It will actually make cars MORE fuel efficient by replacing bulky mechanical systems with electrical ones that would draw too much power on the current 12v systems. Not only will they be more efficient due to being electrical systems, but also weight will be improved for vehicles as well. The new standard was partly chosen to be 42v because the amperage levels would still be safe enough for people, but more than enough to compensate for the increase in vehicle electronics...

      Also people's stereos won't ne
    • One of the great things about hybrids is that they can piggyback on improvements in well established automotive technologies.

      A vast network of gas stations, ample opportunities to fuel your hybrid

      More efficient internal combustion, even more efficient hybrids

      More widespread 42V electrics? Cheaper electrical components for hybrids.
    • by Mooncaller (669824)
      You prove that enviro waccos are ALL a bunch of ignorant twits. Go back to school, and come back after your balls have dropped.

      The luxury market does not drive any portion of the auto industry. It is the least profitable buisness segment. New tech appears in the luxury models only because that is the only economic way to proof it (beta testing). So the luxury lines provide a testbed for development, which justifies their existence. The auto industry does not ever develop tech that can not be applied acros

      • Re:Hybred Voltage (Score:3, Interesting)

        by Technician (215283)
        For electronics that a consumer can contact, the voltage still needs to be limited. With lots of grounded metal nearby, doing auto wireing is kinda like wireing your house circuit breaker panel while standing in a puddle in bare feet. It's not a great idea at high voltage.

        This means that for a given efficiensy, the wieght of the wiring is proportional to the square of the current. I.e. Twice the current needs 4 times the copper.

        Anybody want to take a stab at figuring wire sizes for a 1 volt drop in tw
  • Why 42 volts? The first thing that comes up is how to convert it to 110V AC! Methinks the battery manufacturers are pushing for this mediocre solution in order to ensure that plenty of new batteries get on the market before replacing those yet again with a better standard. I tell ya, somewhere, there's warehouses full of soon to be obsolete batteries, and they're all going to waste.

    Of course, in the unlikely event that exactly the opposite happens, and we experience a shortage of 12 V batteries, Just ge
  • Note to self... buy stock in 60-Volt battery jump-start kits and AAA.
  • Oh Great. (Score:5, Funny)

    by robogun (466062) on Sunday June 15, 2003 @01:45PM (#6205086)
    My neighborhood already rocks with jackasses with 3,000 watt sound systems in their cars. Just what we need, 12,000 watt sound systems at 3 in the morning.
  • Everybody knows that the answer is 42...

    volts...
    • Re:This is obvious (Score:3, Insightful)

      by throwaway18 (521472)
      I remember an article in an IEE magazine about this a couple of years ago.

      A nominal 12V car battery produces about 13.8V when fully charged. When it is being charged the voltage across the terminals can be as high as
      15.5volts. The voltage also varies with temperature and load.

      Electrical systems must meet more stringent safety requirements if they use 50V or more. 42V was chosen to keep within the 50V limit during charging.

      Some people are confused about the reasons for a higer voltage. The amount of power
  • Cool! (Score:5, Funny)

    by Anonymous Coward on Sunday June 15, 2003 @01:47PM (#6205093)
    Now I can have 2 blue lights under my D-reg Ford Escort!
  • by green pizza (159161) on Sunday June 15, 2003 @01:47PM (#6205094) Homepage
    This will be really nice when I find myself needing a jump... now I'll need three or four 12v batteries daisy chained to do a jumpstart.

    Not to mention the other downsides (easier to get shocked from 36+ volts, easier for the electrical system to fry itself in a flood situation, etc).

    Is it just me, or is the automotive industry quickly moving to purely disposable/recycleable cars? When I look at a 2003 model car, I have a hard time picturing it still running and still together in 15 years. Really makes me wonder what a 2010 model car will be like.
    • by qbwiz (87077) <johnNO@SPAMbaumanfamily.com> on Sunday June 15, 2003 @02:33PM (#6205390) Homepage
      A 2010 model car will only be designed to last 8 years; a 2015 model car will only be designed to last 3 years. I'd recommend staying away from cars and the roads every year past 2017.
    • by XO (250276) <blade.eric@[ ]il.com ['gma' in gap]> on Sunday June 15, 2003 @02:43PM (#6205454) Homepage Journal
      I bet people said the exact same thing in the 50's and 60's when they went from 6v to 12v.

      Well, similar things, anyway.

      I've got a 1985 pickup that still runs like a champ, althogh it's got a lot of not-right parts mounted to it, and several pieces on the engine are outright broken. lol.

      I've got a 1993 dodge daytona, that i just put a junkyard engine in, and it runs like a champ, too. actually, it runs better than it did new.
    • This will be really nice when I find myself needing a jump...

      When you someday get a newer car (one that would have a 36/42 volt system), you'll find it has features to greatly reduce the chance you'll run your battery down... like automatic shutoff of the lights if you leave them on by mistake. Most newer cars have these features, and certainly any 42 volt cars in the near future would have it.

      easier to get shocked from 36+ volts

      42 volts is still very safe. Even in europe with stringent electrical s

  • Ummmm... (Score:2, Interesting)

    by davidstrauss (544062)
    I was always under the impression that clean amplification had to do with a clean, stable power source, not high voltage. Also, why does voltage matter for more power-hungry electronics? Amperage is the measure of load. Homes have exponentially increased power comsumption, yet the answer has been higer amperage wiring, not extensive high-voltage circuits. Finally, how does 42V DC convert much easier to 120V AC? Don't you still have to use an inverter?
    • RTFA. It's all explained therein.
    • Re:Ummmm... (Score:3, Insightful)

      by droleary (47999)

      Finally, how does 42V DC convert much easier to 120V AC? Don't you still have to use an inverter?

      Yeah, that's exactly what I was thinking. You can already get a pretty beefy inverter for under $100 to run equipment from your car. I think this is just another case of the big auto manufacturers tacking another $1000 on to the price of a car instead of giving us really innovative vehicles like this [acpropulsion.com].

  • by zulux (112259)
    On of the great things about 12V car systems - that (except for the coils and spark circut)is almost impossible to kill yourself electrically when you tinker with your car.

    42 vols can kill you though - it can easily jump across wet skin.

    • by dougmc (70836) <dougmc+slashdot@frenzied.us> on Sunday June 15, 2003 @01:56PM (#6205155) Homepage
      42 vols can kill you though - it can easily jump across wet skin.
      As can 12 volts. Or one volt.

      It's just that more current will flow with 42 volts than 12 volts -- 3.5 times as much.

      Also, to kill you, the current needs to flow through your heart (unless it's a LOT more voltage, pushing enough current to start cooking your flesh.) This means that you'd have to touch each terminal with a hand.

      I remember the 68 volt batteries that they used for old flourescent lights. Even getting your fingers wet you could barely feel the voltage with them, and not at all having each hand touch a terminal. (Yes, I was a curious kid.)

      In short, I don't see how 42 volts is going to kill you. Even 110 volts has a hard time doing it.

      • The system runs at 36 Volts, The battery is the only thing that is 42 Volts. And there will actually be less current flowing with a 36 Volt system, 1/3 as much. Power = Amps x Volts; Increase Volts, and Amps go down, at a given power. The 68 Volt batteries you speak of probably didn't put out much power.

        The issue with the new 36/42 Volt systems is that at a given power output, the electricity is more likely to choose you than it was at 12/14 Volts(yes, you have a 14 Volt battery in your car). So at 42 Volt

      • by |<amikaze (155975) on Sunday June 15, 2003 @02:21PM (#6205324)
        Exactly. There seems to be a lot of fear about car batteries in general, because people have heard that "10mA of current through the heart can kill someone". They see "500A of cold-cranking power", and start to freak out. What they don't realize is Ohm's law.

        V = I * R, or re-arranged for what I'm going to show, I = V / R.

        I measured my body's resistance using a multimeter, and usually got between 150Kohm and 200Kohm (hand to hand, going through my heart). Plugging this in for a 12V car battery, we get I = 12V / 150Kohm = .00008A, or .08mA. With a 42V battery, we get .28mA. Still WAAAY lower than what can even start to hurt a human. It doesn't matter how many AMPS the battery can put out, with that kind of resistance, that's THE amount of current it can push through.
    • and car companies are all for the end of tinkering.
      if you can't tinker for fear of death then you will aways take it to the dealership and pay $50 an hour to have minor work done n your car
  • by evenprime (324363) on Sunday June 15, 2003 @01:48PM (#6205103) Homepage Journal
    Way cool. One of the arguments that the Big Three automakers have been offering for why they don't make ultra-efficient [technologyreview.com] ICE SUVs is that they require more expensive high voltage electrical systems. That's also one reason (albit a minor one) why gas-electric hybrids are so expensive.

    Car manufacturers have said that it is more expensive for them if their product line has to have two different types of electrical systems. If high voltage electrical systems are going to be standard equipment, though, that argument will disappear.
  • by mizhi (186984) on Sunday June 15, 2003 @01:49PM (#6205106) Homepage
    Oh great, now instead of merely shaking the earth as they drive by, cars with souped up stereo systems will be able to actually crack the pavement and lift small dogs several inches off the ground.
  • by Visigothe (3176) on Sunday June 15, 2003 @01:51PM (#6205115) Homepage
    Why exactly is the ability to attach more electrical crap to my car a good thing?

    Oh, I know... It's so I can check my email, sip my Vente Latte, talk on the phone, keep my McMuffin warm all while driving.

    Woo Hoo! I am so glad I will be able to do that. I hate it when I get distracted by driving.
    • Dear Visigothe,

      It seems as though you have somehow missed basic geek brainwashing. Please report to the nearest re-education facility. You will soon see the light. More gadgets is good.

      The Geek Enforcement
  • by The Optimizer (14168) on Sunday June 15, 2003 @01:51PM (#6205118)
    Saw this one coming when we bought a new car for my wife and it had a water cooled alternator!

    Her car has more luxuries and gizmos than any of our previous cars: Navagation System, Universal Garage Door Opener, 11-speaker sound system w/ DSP, CD Changer, Rear hatch auto-closer (close hatch the last inch), 8 airbags, 16-way power seats, rear wiper arm, etc.. bla.. bla.. bla... and so on..

    I talked to my mechanic about it and they already knew the 42-volt systems were coming. They said 42-volts was chosen to avoid amperages that would harm humans while providing enough capacity for all the stuff being piled onto the latest models.

    It's a small miracle that the battery drain if the car isn't driven every day....

    • 16-way power seats, rear wiper arm, etc.. bla.. bla.. bla... and so on..

      It wipes your bum too? How long before this shows up on Darwin Awards [darwinawards.com]?
  • by autopr0n (534291) on Sunday June 15, 2003 @01:52PM (#6205124) Homepage Journal
    Check it out. Just $20 or so [excess-solutions.com]. Radioshack sells an adaptor but it's $99. Fucking rip-off artists. There are a couple of cars out today that have 110VAC outlets already.

    One of the main advantages of the 42 volt system is that you can have electronic, rather then hydrolic brakes.
    • Yeah, you can convert 12VDC to 120VAC, but you need one heck of a lot of amps running through your car's electrical system in order to do it. Switching to 42VDC means you have less chance of melting the wires in your car.
      • More specifically, it allows you to have smaller wires (uber good... putting a 500watt inverter in the trunk of a 12v car requires several pounds of very thick cable).
        • You know, I'm not disagreeing or anything, but people keep saying this and it still doesn't make any sense to me. The heat should be caused by resistance, meaning based on current, not voltage. I mean, to my mind, anyway. The current remains the same whether you have high volts or high amps, so why does raising the voltage and lowering the amperage mean you can have smaller wires? Ohm's law would seem to suggest that it won't make any difference, your wattage will remain the same. Could someone please fill
  • by di0s (582680) <cabbot917NO@SPAMgmail.com> on Sunday June 15, 2003 @01:54PM (#6205137) Homepage Journal
    It seems cars will have dual systems for a while for legacy equipment."
    My late Ford Pinto isn't legacy equipment, you insensitive clod!
  • self sustaining arcs (Score:2, Interesting)

    by Anonymous Coward
    The only problem I see with this is that a 12V system cannot self sustain an arc while a 42V system easily can. If a 42V car gets in an accident, the higher voltage system may present a problem for emergency workers as they could receive a nasty electric shock while trying to open the car up to get the passengers out.
  • by Mononoke (88668) on Sunday June 15, 2003 @01:57PM (#6205164) Homepage Journal
    Higher voltage system allows lighter gauge wire to carry the same amount of current (weight savings).

    Higher voltage systems are less affected by corroded contacts and connections.

    Higher voltage systems allow physically smaller fuses for the same power handling.

    All of these allow cheaper cabling, connectors, fusing, etc.

  • That's bollocks (Score:5, Informative)

    by Rosco P. Coltrane (209368) on Sunday June 15, 2003 @02:02PM (#6205197)
    A 42-volt system will slash weight

    Where ? 12V lead/acid batteries have 6 elements, 42V batteries would have 21. That's 21 lead plates and associated acid cell. The only thing that would be lighter would wire harnesses, because the wires would be lower-gauge wiring since they wouldn't have to transport as much current. I can't see that being a real weight economy.

    improve fuel economy

    How ? do 42V alternators have a better efficiency than 12V ones ? And even if that was the case, wouldn't, say, driving the alternator with something else than a rubber belt improve efficiency much more dramatically ?

    permit the replacement of many mechanical parts with electrical ones

    How ? what are the mechanical parts that can't be replaced by 12V electrical equivalents that could be replaced by 42V ones ?

    power all sorts of new gizmos like seat heaters, video, etc,

    I can't wait to see cars with seat heaters or video units ...

    and, of most concern to us, improve efficiency for all automotive electrical devices

    I don't know about overall efficiency, but in all fairness, that's true : it's easier to step the voltage down than up. So yes, many devices would become lighter, cheaper and probably more efficient.

    opening the door to higher audio amplifier power with far less complexity than the current crop of 12-volt, high-power amplifiers. Not only can will this translate to lower cost and more compact aftermarket power amps, even head units could cheaply integrate 100-plus RMS watts per channel power.

    That's about the only application where I can see a 42V system be useful.

    All I see in that "improvement" is trouble, exactly like when cars switched from 6V to 12V, and more money to aftermarket accessory makes. For many years, you'll have dual-voltage devices (complicated and defeating the purpose of having a higher voltage in the car) that will be more expensive and heavier, you'll have to buy another cell phone charger, power-supply, CB and whatnot, you'll have to use voltage converters, people without a clue will plug 12V devices in 42V cars, giving more money to garages, ... Okay, when the switch to 42V is made, then everything will supposedly be peachy. But that's not tomorrow : there are still cars around with 6V batteries, or negative hot, *today* while those standards are supposed to be long dead.

    In short, a half-load of technical shit, trouble for everybody and a lot of money for the automotive industry ...
    • The only thing that would be lighter would wire harnesses, because the wires would be lower-gauge wiring since they wouldn't have to transport as much current. I can't see that being a real weight economy.

      Actually, in some racing vehicles the wiring harness is replaced with one piece of fiberoptic cable which runs around the car, and a couple of positive leads which do likewise. Turns out you save a lot of weight by eliminating all that excess wiring since for many devices you have to run multiple wir

      • Where the power is (Score:3, Informative)

        by ChrisMaple (607946)
        power loss in wire = resistance of wire times square of current. If voltage at the load is 3 times larger and current is 1/3 as large, the power at the load is constant, but the resistance of the wire can be 9 times higher for the same power loss in the wire.

        So the wire can be 1/3 the diameter. (Ignoring the fact that the smaller wire won't dissipate heat as well)

    • Re:That's bollocks (Score:3, Insightful)

      by Have Blue (616)
      people without a clue will plug 12V devices in 42V cars, giving more money to garages

      This problem is easily removed by making the plugs incompatible.
    • Re:That's bollocks (Score:3, Informative)

      by Gumber (17306)
      regarding the ways in wich having 42v electrics can improve fuel efficiency.

      42v electrics makes it practical to throw around enough power to do things like:

      1. Electrically operated valves can offer increaced flexibility in valve timing, allowing a broader efficiency band for the engine.

      2. Electrically operated accessories mean that things like Airconditioning and power steering don't take more power than they need when operating at high RPMs

      3. Starters and Alternators can be replaced by motor-generat
    • by aquarian (134728) on Sunday June 15, 2003 @06:01PM (#6206726)
      A 42-volt system will slash weight

      Where ? 12V lead/acid batteries have 6 elements, 42V batteries would have 21. That's 21 lead plates and associated acid cell.


      Get with the times. Upping the voltage allows the same punch with less current, which allows the use of smaller, lighter, NiMH batteries. Of course NiMH could be built in larger sizes, but they're not -- and being able to use smaller, commodity sizes is a hell of a lot cheaper. In fact the Honda Insight and Toyota Prius use commodity NiMH 'D' flashlight cells chained together in a big battery pack. 35 of these in series gives a 42V battery with more oomph than a stone-age lead-acid wet cell, is longer lived, more reliable, hardly affected by temperature, and a fraction of the weight. In case you haven't noticed, car batteries are *heavy.* Engineers love to be able to reduce vehicle weight, but the real savings is in shipping cost!

      the wires would be lower-gauge wiring since they wouldn't have to transport as much current. I can't see that being a real weight economy.

      No, but it sure is cheaper -- and more reliable. Higher voltage is less affected by bad grounds, corrosion, etc., which are the source of most vehicle electric problems.

      improve fuel economy

      How ? do 42V alternators have a better efficiency than 12V ones ? And even if that was the case, wouldn't, say, driving the alternator with something else than a rubber belt improve efficiency much more dramatically ?


      Yes, higher voltage devices are more efficient. But besides that, the move is toward direct drive, combination, generator/starter/traction motors that live in the bellhousing like the one in the Honda hybrids. There's no belt, and no losses (or maintenance issues) due to that. There's one device, not two or three. It lives in a thermally stable, clean, dry environment. In ten years, more cars will have this hybrid-like architecture than not, whether or not they'll be true hybrids. It's simply a better way to build a car.

      permit the replacement of many mechanical parts with electrical ones

      How ? what are the mechanical parts that can't be replaced by 12V electrical equivalents that could be replaced by 42V ones ?


      Electric air conditioning compressors, power steering and brake servos, etc., become viable with a higher voltage system. Higher voltage allows them to be smaller, lighter, cheaper, and efficient enough to surpass current technologies.

      and, of most concern to us, improve efficiency for all automotive electrical devices

      I don't know about overall efficiency, but in all fairness, that's true : it's easier to step the voltage down than up. So yes, many devices would become lighter, cheaper and probably more efficient.


      Well if you don't know, then STFU. "I don't know what I'm talking about, but here I go anyway..."

      And yes, many devices would become lighter, cheaper, and more efficient. A few watts here, a few watts there, it all adds up. A few dollars here, a few dollars there, that all adds up too -- except that automakers think in *fractions of pennies.*

      opening the door to higher audio amplifier power with far less complexity than the current crop of 12-volt, high-power amplifiers. Not only can will this translate to lower cost and more compact aftermarket power amps, even head units could cheaply integrate 100-plus RMS watts per channel power.

      That's about the only application where I can see a 42V system be useful.


      I'm sure.

  • He was charged with battery!
  • It's because we use more power in the cars today. It's not just for lights and the engine anymore. Take a look at all the things that are put into cars today. 12v is a problem and you have to run thick cables to all these things. It is not very practical anymore. Fx some cars have eletric AC (for non-tropical locations).
  • by Animats (122034) on Sunday June 15, 2003 @02:10PM (#6205259) Homepage
    This isn't about car audio; that's just where the poster found the story. This is about driving larger motors, like power steering. Power steering is about to go electric. The plants to build electric power steering units in volume have been under construction for months now. 12V power steering has been tried; it's on the Fiat Punto now. It doesn't work well, and scaling it up to larger vehicles hasn't been successful.

    The 2004 Chevy Malibu will launch this fall with a 42V electrical system and Delphi E-Steer electrical power steering. It's not full steer-by-wire; there's still a mechanical linkage. But that's for backup, through a flexible coupling. The real steering is done with a sensor on the steering column, a motor in the steering box, and a computer watching speed, steering angle, skid information, and such.

    This will make converting cars to computer control much easier.

  • by dougmc (70836) <dougmc+slashdot@frenzied.us> on Sunday June 15, 2003 @02:10PM (#6205261) Homepage
    36 volts rather than 12 volts would mean that your wires could be 1/3rd the size and still transmit the same power. This is the real reason they're doing this.

    The new batteries shouldn't cost 3x as much either. Yes, it will have 3x as many cells, but the cells could be 1/3rd the size, which could give the battery the same capacity as one of today. Of course, they do expect higher electricity demands in the future, so batteries will probably get larger (and would have to do so even if we stayed with 12v) so the size and price of batteries will probably increase somewhat.

    As far as providing 110V AC circuits, they can do this pretty easily and cheaply now, if they wish. 36V systems won't make this that much easier. (It will make it easier to provide higher capacity 110v circuits, however. A hair dryer draws 1500 watts, which is 10 amps at 110 V or 125 amps at 12 volts. 10 amps is a lot, and 125 amps is massive. Assuming a 100% efficient inverter (which isn't possible), a 36v system could would only need 42 amps to power that hair dryer. Still a lot, but the wires needed to power the inverter would be a lot smaller.

    (Of course, 42 amps is still a lot, and so it's unlikely that many cars will have an inverter capable of producing 1500 watts of power. But 500 seems likely.)

    And no, I wouldn't expect this to affect the 1000+ watt stereos out there much. A 36v system would make wiring up one of these stereos simpler, because you could use smaller wires, but other than that it would be the same. The stereo could have some smaller wires internally as well, so in theory it might be a bit smaller and cheaper, but I'd expect that effect to be minimal.

  • if I'm wrong, but I heard 24V is the "lethal treshold" voltage, i.e. anything above it can kill, below - not (YMMV of course). So if your car breaks and you get your limb stuck with some powered element, with some bad luck you will fry to death, where 12V was safe, at worst giving you rather painful electric shock and some burns.
  • Because P=IV quadrupling (well, 3.5x) the voltage gives you a four fold increase in power at your maximum safe current.

    On the down side increased voltages require much thicker conductors (or better ones, like gold), and more/richer copper alloys means more expense and weight - not a thing the car industry will be keen on.

    OTOH for electric cars and multistage ones (think hybrid fuel cell charging battery type) battery and capacitor efficiency increases as the voltage rises, and so does energy loss accr
  • by Chanc_Gorkon (94133) <[gorkon] [at] [gmail.com]> on Sunday June 15, 2003 @02:41PM (#6205442)
    What is really needed more is a 12 volt battery that can provide current for longer periods of time. I would rather see a parallel system. 2 12 volt batteries with either 2 alternantors (one for car and all of it's internal acessories and one for the external plugin ones. Also, the second battery could also be charged off of regenerative brakes and or solar cells as well as a alternator.

    I don't see how changing voltage will make cleaner sound. The biggest problem with mobile electronics is lack of a good ground. The ground on a modern vehicle sucks. When I run a HF radio in the car, most of the losses are because of the ground system in the car. It's near impossible to fix that properly. The antenna systems in the car are almost always verticals and normaly you'd either burial radials or have a decent ground plane built. With a car, it's impossible to change the width of your ground plane because it's mobile. Mobile installations almost always require an antenna tuner because of this and this is just to make sure your SWR stays radio safe. You may have a radio capable of 100 Watts, but I have never seen one produce it. Plus the alternator produces alot of hash that needs to be blanked out or filtered out. RF chokes on the power cords and other things to get rid of this noise. When you run off of just batteries, that noise is not there anymore and you don't need those filters. :)
  • Short circuits? (Score:4, Interesting)

    by Zog The Undeniable (632031) on Monday June 16, 2003 @03:30AM (#6209952)
    42V is enough to pass through dirty water, so I anticipate all kinds of problems when things get wet, unless everything is carefully designed to tolerate some electrical leakage. On the contrary, a 12V motor will actually run underwater with no sealing!
  • by thogard (43403) on Monday June 16, 2003 @04:47AM (#6210183) Homepage
    Right now nearly every add on in a car (radio, cell charger, that sort of thing) uses a version of the 7805 or 7812 regulator. These devices can cope with voltages up to 40V and thats considered reasonable based on surges on a 12 v system. With a 42V system, that already exceeds the input voltage of most low cost voltage regualtors and when you figure in for surges at 3x, its outside of all the low cost DC regulators. The resut is a part that is now a single 5 volt regulator may need a swtiching power supply until someone comes up with a 7812 style device that can cope with the much higher voltages.
    • You're right. The 78xx series are only good to about 36V or so. Unfortunately they are linear devices, and dissipate a fair amount of heat when doing their thing. I would rather see small switching supplies used anyway from an efficiency standpoint, like these [digikey.com] or the Panasonic ones at the bottom of this page [digikey.com].

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