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42-Volt Autos
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."
Way cool. One of the arguments that the Big Three automakers have been offering for why they don't make ultra-efficient 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.
"Weapons should be hardy rather than decorative" - Miyamoto Musashi
I think that goes for OS's too
Check it out. Just $20 or so. 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.
autopr0n is like, down and stuff.
but only as legacy from being military vehicles, 24 volt systems ae needed to crank some of the old and new massive diesil engines in the transport trucks ect. the hummer has the 24 volt system so that it can jump start(or in military terms slave start)a tractor trailor.
since some military trucks spend a lot of time sitting and not driving this happens more than you might wish to think
I used to have a cool sig, back when I cared
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.
I'm a blockhead.
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A 42-volt system will slash weight
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... 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.
...
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,
In short, a half-load of technical shit, trouble for everybody and a lot of money for the automotive industry
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
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.
Toronto-area transit rider? Rate your ride.
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.
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.
.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.
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 =
The difference in voltage between the two terminals is of magnitude 48 but the current is flowing in the reverse direction from "normal". If you attached a voltmeter, it would read -48 (attach it backwards and it will read 48...)
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.
Gorkman
It is not that simple. As you apply higher voltage to your skin, its resistance will decrease very rapidly, and in the result the current flowing through your body will be much greater. And yes, 48V can kill you.
So the wire can be 1/3 the diameter. (Ignoring the fact that the smaller wire won't dissipate heat as well)
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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.
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.