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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
(Score: 1, Interesting) by Anonymous Coward on Monday February 26 2018, @12:30AM (72 children)
12V has a couple of things going for it -- as long as there are lower cost cars using incandescent light bulbs, the 12V filaments are thicker and more vibration resistant than higher voltage bulbs. Also, 12V switches don't arc, but special switches with arc extinguishing are required over ~30V DC...or more expensive solid state switches.
(Score: 0) by Anonymous Coward on Monday February 26 2018, @12:47AM (33 children)
The article explains they will be utilizing a dual voltage system, 12 and 48 on different circuits. This is probably specifically for the low power stuff like lights, instrument cluster, cabin lights, aux power and what not.
(Score: 2) by Grishnakh on Monday February 26 2018, @02:21AM (32 children)
This is probably specifically for the low power stuff like lights, instrument cluster, cabin lights, aux power and what not.
Why would you need 12V for any of that stuff? Lights are LED now, cabin lights should be if they aren't already, the instrument cluster has been using LEDs and other stuff for ages now, etc. The only thing you "need" 12V for is your cigarette lighter socket, because commonly-available accessories that plug into these are 12V.
(Score: 1, Insightful) by Anonymous Coward on Monday February 26 2018, @02:28AM (20 children)
what LED runs on 48 volts?
might as well move to HPS cabin lights
(Score: 5, Informative) by requerdanos on Monday February 26 2018, @02:39AM (6 children)
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
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)
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)
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
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
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
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)
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)
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)
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)
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)
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)
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.
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)
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)
...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.
...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.
...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
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)
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)
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)
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):
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
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.
(Score: 2) by sjames on Monday February 26 2018, @03:52AM (10 children)
Cost. The 12v rated contacts in all the switches won't stand up to 48v at all. All of the off the shelf motors, switches, etc are 12v. Those instrument clusters all run on 12V. Basically, adding a voltage converter will be a LOT cheaper than redesigning all of that and totally replacing all of those off the shelf parts.
(Score: 4, Insightful) by Grishnakh on Monday February 26 2018, @04:01AM (9 children)
Mostly wrong.
1. Instrument clusters: no one reuses instrument clusters. Every car has a different one, and every car gets a completely different one when it's redesigned for a new generation. You have to redesign your instrument cluster every 3-6 years anyway, so designing it for 48V is no extra cost.
2. Switches: lots of stuff is going away from high-current switches, and moving to extremely low-current switches with MOSFET power switching circuits. This lets you use the vehicle network to get commands from switches, and then remotely actuate stuff elsewhere in the car (like in a different door, in the case of window switches), so wiring is simpler and you don't need to route high-power wires all over the place.
3. Motors do get changed from time to time. 48V motors are smaller and cheaper than 12V ones because you need much less copper winding to get the same torque.
(Score: 2) by sjames on Monday February 26 2018, @04:30AM (8 children)
The cluster itself may change from year to year, but the parts that make up the cluster don't.
Perhaps going away, but far from gone.
in the same volume with the same available data on lifetime, 48v motors would be cheaper. But 12v motors for automotive applications are in volume production and have been for a long time.
(Score: 2) by Grishnakh on Monday February 26 2018, @06:26AM (7 children)
The cluster itself may change from year to year, but the parts that make up the cluster don't.
They absolutely do: every new cluster means you need an all-new PCB designed. If you're going to redesign the PCB, you might as well redesign the power supply on it. Why on earth would you stick the same 12V power supply on there, and then design in a 48V-to-12V DC-DC converter somewhere, when you can just slightly modify the power supply on the cluster PCB to handle 48V?
(Score: 2) by sjames on Monday February 26 2018, @06:43AM (4 children)
Because you already need the 12V converter, so it comes "for free"
(Score: 2) by Grishnakh on Monday February 26 2018, @03:59PM (3 children)
What do you need the 12V converter for? No, it's really not "free": adding more 12V loads means your converter needs to be upsized, and you need heavier-gauge copper wiring to these loads where you were too lazy or stupid to just modify the design for 48V operation when you were redesigning it in the first place. This doesn't make any sense at all.
(Score: 2) by sjames on Monday February 26 2018, @07:10PM (2 children)
People expect the aux power socket (the "lighter") to provide 12V at a decent amperage. After-market equipment is expected to just work.
EVENTUALLY, the 12V will go away entirely. I think you way under-estimate how much carry-over there is from year to year in design. Automotive engineering is quite conservative as a whole.
There's a reason that part catalogs generally include a list of model and year ranges that the same part fits. Warranty repairs and recalls are expensive and damaging to reputation.
(Score: 2) by Grishnakh on Monday February 26 2018, @07:33PM (1 child)
Yes, it is conservative and a lot of parts are carried over, but that does not include instrument clusters (they're always updated with new generations, and sometimes in the middle of generations too), nor does it extend to circuit designs. As I said before, it would be completely idiotic to design an all-new instrument cluster PCB and not bother to design in a new power supply if you have a 48V bus available. It's not like designing for a 48V supply instead of 12V is something completely new and different. And you're not going to use the same DC-to-DC converter for a lighter socket as for something critical like your instrument cluster; that too would be idiotic, because someone could plug something into the lighter socket causing the DC-to-DC converter to fail, and now your dashboard is dead.
(Score: 2) by sjames on Monday February 26 2018, @09:10PM
As opposed to now where someone could plug something into the lighter socket and the whole electrical system is dead?
Or more likely in both cases, a fuse blows and life goes on.
(Score: 2) by hamsterdan on Monday February 26 2018, @11:31PM (1 child)
Don't underestimate bean counters. My friend's leaf has a standard 12v lead acid battery, even if the car is 100% electric. when his battery died, the car wouldn't start. because the single 12v battery was dead. An F-150 gave him a boost, a V8 gas-guzzling jump-started an electric car, so yes, everything is possible.
One of the advantages of switching to 48v is wire size, even on gas-powered vehicules, we're talking about lots of pounds that could be shaved from the vehicule's weight, but if they leave legacy 12v in there for *everything* on the market, fine by me. For those of you old enough to remember the cigar lighters in cars, it was a legacy from when it was really used to light cigars.
(Score: 2) by Grishnakh on Tuesday February 27 2018, @03:02AM
The Leaf most likely has a 12V battery because off-the-shelf parts from Nissan's parts bin are all 12V, and a single not-top-selling model just isn't enough to get a bunch of 48V accessories made (which wouldn't help the Leaf that much at this point anyway, because its main battery is 380V, and the auto industry has been talking about a new voltage standard for decades but never actually agreed to one). If a large carmaker switches ALL its models to a new voltage standard, the old 12V stuff will be disappearing pretty quickly, if not within one car generation, definitely two.
Here's [mynissanleaf.com] an interesting post about those Leaf batteries BTW.
(Score: 2, Interesting) by Ethanol-fueled on Monday February 26 2018, @12:48AM (4 children)
Don't forget about boats. Your garden-variety Party Barges run from 12 volt marine batteries, then you throw an inverter in there, and now you can operate test equipment in the field and yet still have a wide latitude for Jerry-rigging in emergencies.
But back to car motors, American (and other) automotive manufacturers have long been interested in creating ever more efficient internal combustion engines. For example, turbocharged 3-cylinder motors which deliver ridiculous amounts of horsepower given their small footprint. But you wouldn't believe that given that American drivers like their power.
Personally I'm partial to the 4-banger + 5-speed manual transmission. Allows you to give chase and beat up all of those obnoxious fuckers who drive sports cars with automatics.
(Score: 2) by Runaway1956 on Monday February 26 2018, @01:45AM (3 children)
You've just reminded me of my youth. My first car was pretty much dead before I ever laid eyes on it. Acceleration was abysmal. The road we lived on led out onto Highway 18, between two curves. I would wait for no one to be in sight, then pull out - and often times, a truck would come around the bend behind me, bearing down on my young ass. Scary! I learned that you've got to have something that will accelerate when you need it.
No, I don't run huge twelve cylinder engines, and I never felt the need for 500 (or more) horsepower - but I have always demanded something that would run. When I punch that accelerator, I expect to be pushed back into the seat.
Back in the day, few of your 4-bangers had that ability. Today? Some of those little 4-cylinders are amazing. Not to mention the V-6 engines. If the manufacturers were to stop building V-8 engines today, few people would really miss them.
At the moment, I'm pretty happy with a new version of the old inline-six engine. Chevrolet's 270 powers a Trailblazer away from a stop sign pretty respectably. Internally, it seems to be pretty much the same as any old inline, but electronic ignition and fuel injection makes it an entirely new beast.
(Score: -1, Flamebait) by Anonymous Coward on Monday February 26 2018, @06:23AM (2 children)
Once again Runaway is triggered, and starts talking about his ass, and trucks, and the day his mom got out of prison. David Allen Coe [youtube.com] And we end with a Chevy ad? Offtopic does not begin to cover this!
Mine was always a Ford family, so I must despise you from a distance, Runaway. Thank you again for disrupting the flow of discussion with totally irrelevant random recollections from your past.
(How old is he, anyway?)
(Score: 0) by Anonymous Coward on Monday February 26 2018, @06:53AM (1 child)
Judging from his posts, he has seen a lot. And I feel a bit wiser after I have read his posts.
(Score: 0) by Anonymous Coward on Monday February 26 2018, @09:30AM
Either you are starting from very low levels of wisdom, or you are Runaway commenting about his own post as AC. These are the only two possibilities.
(Score: 2) by frojack on Monday February 26 2018, @12:53AM (18 children)
Will they get away with thinner wires?
Also why would they need spark arrestingly switches? There are plenty of spark sources in the typical car. Not to mention cigarette lighters.
No, you are mistaken. I've always had this sig.
(Score: 2, Interesting) by Anonymous Coward on Monday February 26 2018, @01:04AM (2 children)
> why would they need spark arrestingly switches?
An arc across the switch points quickly erodes the contacts and destroys the switch -- instead of thousands of uses (over the life of the car), you might get a hundred or something. Arc welding voltage is ~30V DC, anything higher than that will maintain an arc for awhile when the switch is opened (turned off).
AC switches are a different problem, since the alternating current goes through zero volts 120 times/sec (or 100 in 50Hz countries)...the arc can't last longer than 1/120 sec.
(Score: 1) by anubi on Monday February 26 2018, @07:05AM
Another thing is that the day of the mechanical switch is fading. It won't go out, but MOSFETS are making great inroads as they can easily be controlled with much smaller signals, like a relay, and can be tailored for controlled ON and OFF time.
One thing I am looking forward to is the elimination of the starter motor and alternator as separate entities. This may already exist somewhere, but it sure seems to me that the flywheel, loaded with neodymium magnets, would make a good rotor for a motor/generator. The hybrid cars may be using this already - I am not up to speed on their design. I do know that every place I have a contact, I have a high probability of failure. Especially on a car.
Ever seen those guys "steam cleaning" a modern engine, with all those sensors and wiring? I cringe and wonder how much longer that engine will run with forced water application and corrosion starting up in its sensors... almost like seeing a Katrina or Harvey flood car. Pretty on the outside, and what evil lurks in some little sensor contacts, corroding, deep in the bowels of the thing? But it looks great on the used car lot.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 0) by Anonymous Coward on Monday February 26 2018, @07:33PM
Just looks at how long a set of points will last on a 64 ford pickup and you'll get an
idea about how arcing kills contacts. One was lucky to get 3000 miles before you
had to file the points contacts.
(Score: 3, Informative) by sjames on Monday February 26 2018, @04:00AM (14 children)
Thinner wires but thicker insulation due to safety regulations.
Arresting the spark isn't due to fire hazard, it's so the switch contacts don't pit and erode. They need the switches to hold up until the warranty is expired.
(Score: 2) by Grishnakh on Monday February 26 2018, @06:32AM (13 children)
Thinner wires but thicker insulation due to safety regulations.
Doubtful. Typical wire jackets can already handle hundreds of volts (probably 600V), so 12V -> 48V isn't really a change, unless the OEMs are getting special wire with thinner insulation than usual. (i.e., If you go out and buy some wire right now, there's no such thing as "12V wire"; it all handles voltages far above anything you're likely to throw at it. Wire with insulation for only 12V would be ridiculously fragile anyway, since you don't need much insulation for such low voltage.) Even if they are using thinner-insulation wire, insulation doesn't add significant cost, unlike copper.
(Score: 2) by sjames on Monday February 26 2018, @06:39AM (8 children)
I'm thinking more for mechanical requirements rather than electrical.
(Score: 2) by Grishnakh on Monday February 26 2018, @04:29PM (7 children)
Here again, you're not making much sense. They *already* use a particular amount/type of wire insulation in cars for mechanical reasons, rather than electrical, because cars are a harsh environment (lots of vibration), and the voltage is extremely low. Changing to 48V isn't going to affect that significantly. 48V is still low-voltage, and the mechanical requirements are the same.
(Score: 2) by sjames on Monday February 26 2018, @06:54PM (6 children)
And if you use a smaller gauge wire, you have to replace that with something.
(Score: 2) by Grishnakh on Monday February 26 2018, @07:46PM (5 children)
Why are you so argumentative on this topic? If you use a smaller gauge wire, you just use a smaller gauge wire. They already have small-gauge wires in cars (for ultra low-current signal lines); it's not like they have to go find something new. They have a whole range of wires they already use, now they just use more of the smaller stuff and less of the larger stuff.
(Score: 2) by sjames on Monday February 26 2018, @09:08PM (4 children)
I'm replying because you're replying. Why are YOU so argumentative on this topic?
(Score: 2) by Grishnakh on Monday February 26 2018, @09:35PM (3 children)
Because you keep coming up with things that aren't really problems with converting to 48V and claiming that they are, that's why. The ideas you have are simply wrong: wiring insulation is not a significant factor, redesigning parts and intentionally sticking with 12V when it's no extra work to design for 48V is stupid and not going to happen. In this thread, you really seem to be hung up on wire insulation for some odd reason. What is your obsession with this? Do you just *have* to get the last word in? There's no difference in wire for 12V or 48V systems, I've said it over and over.
(Score: 2) by sjames on Monday February 26 2018, @11:31PM (2 children)
Problems? I have presented no problems, just likely solutions for the transitional period as automotive systems transition to 48V. I do hope they don't cheap out on the wires. And there's no reason that can't save some copper and still have adequate mechanical properties.
Why do you expect a conservative industry to re-design the entire electrical system in one shot when they don't have to?
(Score: 2) by Grishnakh on Tuesday February 27 2018, @03:05AM (1 child)
Why do you expect any industry to re-design something major and stick with an obsolete standard instead of just moving to the new standard that they've already adopted?
(Score: 2) by sjames on Tuesday February 27 2018, @04:25AM
Because that's how it tends to be done. It spreads risk as well as engineering effort and part validation. Given that there are so far no deployments, how much testing of a 48v window motor do you suppose is available? Everything I have read indicates that the intention is very much to use a DC-DC converter for all of the accessory systems and even the engine controller. See these [jalopnik.com] links [assemblymag.com] for example.
Beyond that, I doubt they will go 48v on all models in the first year. They'll want to use the same parts as much as possible across the line.
As I said, they will likely EVENTUALLY move other parts over to 48v, but that will be a while.
(Score: 3, Informative) by anubi on Monday February 26 2018, @07:15AM (3 children)
I just hope they don't start using aluminum wire!
Looked at any modern washing machine motors? Aluminum wire! With orange lacquer so it LOOKS like copper.
I found that out when I decommissioned a machine with a rusted out tub. While I did recover several handfuls of nice colored wire for my projects, what became a firepit, and a mount for a sink I wanted for the back yard, I had kept the motor as a donor for copper wire that I like for things like tying plants. To my chagrin, when I ground the motor open to get to the wire wound on the stator, the wire itself was aluminum!
No problem for me, and the motor did not fail because of this, but I found it interesting that the motor was wound with orange-lacquered aluminum wire. Pretty obvious when I took a small file to it.
Also, note a lot of the "Heavy Duty 4 Gauge Jumper Cables" look like copper. Look for "CCA". I know, we automotive types see CCA and think "Cold Cranking Amperes". That's not what the manufacturer of those cables meant. "CCA" is their term for "Copper Clad Aluminum". That's right, Aluminum wire in your battery jump cables. That nice low-gauge rating may not mean as much as you was hoping it meant.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 2) by deimtee on Monday February 26 2018, @10:24AM (2 children)
Aluminium is less ductile and less dense than copper, but per linear mass is both stronger and a better conductor. Per unit volume copper is almost twice as good as a conductor, but is three times heavier.
Fixed wiring as in a motor probably should be aluminium, it would reduce the total weight.
One of the main reasons for not using it is actually the problem of terminations. It is difficult to reliably connect to as the surface oxide layer is basically sapphire. CCA sounds like an interesting solution to that.
CCA Jumper cables, yeah those cheating fuckers need a few CCA's through their privates. Aluminium wire will crack if repeatedly flexed as happens to jumper cables.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 2) by Grishnakh on Monday February 26 2018, @03:53PM
Fixed wiring as in a motor probably should be aluminium, it would reduce the total weight.
I doubt that. Motors have two main parts: the windings and the core (this applies to both the rotor and the stator, though some motors omit windings in the stator and use permanent magnets). The core is usually made of thin laminations of iron, and is used for conducting magnetic flux. Using aluminum windings would require you to significantly enlarge the whole motor, including the core, which means you'll be adding a bunch more mass in iron, which is even more dense than copper.
Iron is cheap, though, so for cost-sensitive applications where you care more about cost than size, and weight isn't a big concern, it can make sense. A laundry machine is a good example of such an application: heavier is actually better here usually (modern washers actually add concrete to increase mass), and there's generally plenty of room for a motor. But in a car, even if the motors weigh the same, size is much more important than shaving a few pennies of cost.
(Score: 2, Informative) by Anonymous Coward on Monday February 26 2018, @04:25PM
Copper has the same problem. Neither metal has a fatigue limit -- i.e., both copper and aluminum will inevitably fail under cyclic loading/unloading (no matter how small the load). Aluminum does fail faster, though. If you don't use your jumper cables more than a couple times a year (like most people) then either kind could last a lifetime.
So as with most things in life, it's a cost/benefit tradeoff. CCA should have a substantially lower upfront cost. It will also weigh less, which might be an advantage (keeping it in your car -> less mass -> less fuel consumed? This effect is probably in the noise).
On the other hand, aluminum is thicker than copper for the same conductivity, so CCA cables will be physically larger. Also your copper cables will probably be worth something in scrap later while the CCA cables will probably be worthless.
(Score: 3, Informative) by corey on Monday February 26 2018, @01:15AM
Merit to the switch argument but incandescent is old tech anyway, new cars are moving to LED lighting anyway.
(Score: 3, Insightful) by fyngyrz on Monday February 26 2018, @02:59AM (5 children)
...this technology is on its last legs anyway. Not really a current factor.
(Score: 3, Funny) by Anonymous Coward on Monday February 26 2018, @06:41AM
My first car was 6v, positive ground. Also had left-hand thread lug bolts on the driver's side. something left over from wagon axle nuts. But I converted it to 12v neg ground, to keep up the the times and to avoid having the jumper cables attached incorrectly by young 'uns. Problem was, I had to go through and take out and reverse every single bulb in the car, 'cause the 'lectricity was used to going the other way, and it just could put up with the positive poll being on the wrong side. Starter motor ran backwards, to, so the engine started running backwards. Not so much of a problem, but I only had one forward gear, and three in reverse. So I just turned the front seat around, put a flex extension on the steering, put alternate pedals and a mirror to see the instrument cluster. Drove for nigh on to a decade like that. Kids these days! Don't even know what a "ground" is!
(Score: 1) by anubi on Monday February 26 2018, @08:01AM (3 children)
Ok, I can't "resist"... you left yourself so wide open with that pun. So I will take you up on it.
Ummm, yes, it IS a current factor. Typically LED's give a helluva lot more light per watt than incandescent will. [cnet.com] Especially lower temperature incandescent like automotive. You will get the same light from 500mA of LED current as you did from 2 Amperes of current to an incandescent.
Not only that, if done right, the LED will easily outlive the car and its owner. No more getting pulled over for burned out tail light.
The only thing that seems to make an LED dim over time is how hard it is driven... ease off a bit and the thing will live longer than you will.
Drive 'em hard and they will fail in seconds, minutes, hours, days, weeks... and most designers seem to try to make the numbers look better than the competition - and design stuff that does not last very long. Stuff like lumenaires for businesses. They put 'em in and within a year, al lot of the die are, well, dead.
Given the lifetime, more robust connections can be made, which move the tradeoff from ease-of-replacement to reliability. Replacement of an LED tail light assembly could conceivably involve use of a soldering iron and heat shrink - as it the original wiring was crimped in place and sealed by factory automatons. How many times you have run across light bulbs that worked when wiggled because of a corroded connector?
But you are so right... incandescent technologies are nearly completely obsolete. There are very few holdouts where high temperatures and adverse conditions are involved, or spectral requirements of some laboratory devices. I am working toward getting rid of all incandescents in my life, but admittedly the light in the oven is going to remain incandescent for quite some time.
One of the things I really like about LED's is that, between phosphors and physics, I can get darned near any color of light I want. So I do not have to make a spectrum of colors and throw most of it away with filters.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 0) by Anonymous Coward on Monday February 26 2018, @09:12PM (2 children)
An incandescent oven light is desirable for me, as I bake bread and make yogurt often. A little extra heat in an out of the way place is nice to have.
(Score: 2) by Grishnakh on Monday February 26 2018, @10:05PM (1 child)
Huh? The heat produced by an oven light is nothing compared to that produced by the oven's heating elements. An LED light in an oven would be nice, as it would be much whiter and could be brighter than standard oven bulbs. But we don't have other lighting technology that works all that reliably at 500F, so we have to stick with bulbs for now.
(Score: 0) by Anonymous Coward on Tuesday February 27 2018, @07:00AM
He means with the main element off. If his bulb is 40 watts, he's using it as a 40-watt heating element.
We have lighting technology that works much hotter:
https://en.wikipedia.org/wiki/Sulfur_lamp [wikipedia.org]
https://en.wikipedia.org/wiki/Xenon_arc_lamp [wikipedia.org]
https://en.wikipedia.org/wiki/Hydrargyrum_medium-arc_iodide_lamp [wikipedia.org]
Lots of gas-discharge tubes will work fine. Mix them to obtain the desired color of light.
(Score: 4, Insightful) by JoeMerchant on Monday February 26 2018, @03:14AM (6 children)
Well, there you have it: a reason why new cars have to be serviced at the dealer, a reason why a $3 toggle switch can now be billed out at $87.
Lights: all LED, similar reasoning.
I think they stopped at 48V because over 50 you start worrying about serious electric shock on skin contact, and insulation classes ramp up accordingly.
🌻🌻 [google.com]
(Score: 2) by Grishnakh on Monday February 26 2018, @04:09PM (5 children)
Well, there you have it: a reason why new cars have to be serviced at the dealer, a reason why a $3 toggle switch can now be billed out at $87.
Solid state has nothing to do with that. A switch at the dealer is going to be expensive regardless, because it's a product with no competition, as each one is unique to the automaker (and maybe model of car). And then the local dealer marks it up even more because they can: that one is basically a "stupid tax", which you pay if you're too stupid to use a web browser and buy one online.
With much lower currents going through the mechanical portion, solid state switches can last longer than the old kind.
Lights: all LED, similar reasoning.
LEDs generally last the life of the car.
(Score: 2) by JoeMerchant on Monday February 26 2018, @08:10PM (4 children)
Nice thought, and true for the light emitting junction, however: contact corrosion, wire and insulation failure, and a half dozen other things can cause a light to fail, requiring replacement of the lamp module and more.
Sure, they could hard-solder the contacts, but will they?
🌻🌻 [google.com]
(Score: 2) by Grishnakh on Monday February 26 2018, @08:47PM (3 children)
Those things all apply to incandescent bulbs too. LEDs remove the biggest failure point: the bulb itself, plus they eliminate the crappy connection at the bulb itself: with LEDs, you use a much more modern automotive connector to interface the wire harness to the lamp module, instead of being stuck with a decades-old bulb design.
They've had LED lights on cars now for a couple of decades, starting with the CHMSLs (the 3rd brake lights), and some cars have had LED main brake lights for quite a while too. Have we seen significant failures with these? I doubt it.
(Score: 2) by JoeMerchant on Monday February 26 2018, @08:54PM (2 children)
Define significant...
I've definitely seen half-functional LED lamp modules driving around.
🌻🌻 [google.com]
(Score: 2) by Grishnakh on Monday February 26 2018, @09:55PM (1 child)
Well in that case, it sounds like the individual diodes failed, rather than there being a problem with the wiring, connections, etc. LEDs do age and fail over enough time (less if the LED is driven closer to its limit).
(Score: 2) by JoeMerchant on Tuesday February 27 2018, @02:16AM
Sometimes an individual diode, more often half a panel... and let's not even get into those LED matrix billboard signs.
🌻🌻 [google.com]