Tom2

They're just around the corner..... Soon you'll start to see 36V batteries replacing the common 12V battery of today.

These 36V batteries will be backed up by a 42V electrical system.

In the 1st generation cars, we'll see a 42V system with a DC/DC converter to a 12V system. That way, all the current 12V accessories will still work.

A few years later, the 2nd generation cars will completely eliminate the 12V system and run everything on a 42V system. Engineers are still currently working on 42V accessories (think about it-- even current headlights wouldn't last in a 42V system) for these new systems.

There are already a few cars running around in Europe with these new 42V systems, and it is expected to hit the U.S. beginning in 2005. Manufacturers claim that it will be a rapid transition and that most models will be running these new systems within 2 years.

Why, do you ask, are they changing to 42V systems?

Several reasons:

1- Modern cars and future cars will have an increased electical need. 12V systems replaced 6V systems back in the early 1950's. Until recently, a 12V system was sufficient. With the increasing electronics on modern cars, we will soon require these higher voltage systems.

2- Having a 42V electical system will allow automotive engineers to run wiring that is 66% smaller than current wiring. Even alternators/generators will be smaller and lighter weight. This will help keep vehicle weight down and increase fuel economy.

The more voltage in the system, the less current that will be required to power anything in the vehicle. Soon we will see electically powered water pumps, which will free up wasted power of the engine. We might even see electrically operated intake and exhuast valves. With a 42V electrical system, this is entirely possible. Without it, we'll never see it happen.

russianDude

Why can't they just increase the Current (I), and keep the same voltage?

Voltage does not mean sh*t, current is what counts.

Tom2

Did you ever hear of Ohm's Law?

If you run higher voltage, you can use LESS current. Less current means THINNER wires. Thinner wires mean LESS weight. Less weight means better fuel economy.

russianDude

I am not sure I agree that weight of the wire will be less. For Higher voltage you can have thiner wire, but you need more insulator material to shield them from other wires.

Tom2

Okay, russiandude, whatever.

I'm telling you the reasons that they're making the switch. If you don't agree, then fine.

All the information I posted came from one of my Engineering trade magazines. The wiring will indeed be thinner and lighter than current automotive wiring. If you have higher voltage, you don't need as much current.

Think of electrical current as water rushing through a pipe.

Voltage would be the force of the water
Current would be the amount of water flowing through the pipe.

Now, if you could increase the force (voltage) you could do MORE work with a smaller amount flowing (current) though. This would allow you to have a smaller pipe to carry the water.

It's the same thing in electricity.

russianDude

hey, you don't need to tell me about physics... but more voltage will need more insulator material around the wire ( yes you can have thinner wires ).
I guess those engineers just want to save every penny, have they though of making plastic cars?

codehead

The jump in voltage isn't that big--I doubt that you need significantly more insulation (it's not like 3x voltage needs 3x insulation; if that was the case our household wiring would be huge).

There is also interest in electrically controlled valves for obvious reasons. You really need to go to a higher voltage for that to be practical.

Anyway, you can bet it will happen.

Pull_T

I've been reading about these for a WHILE now.
I heard of the switch to 42volt AC prolly 5 years ago.Since then I have eagerly grabbed anything I could on the topics.

Keep in mind I don't know much about it other than sheer theory. So its not like I think I know everything about this crap.......cuz I don't know much at all.......but what i do know is enuff to get me excited,in a purely automotive fashion of course...hahah.

When the 12V DC system was adopted,we did not have nearly as much electrical crap in cars.
Now we have everything from DVD's to stability control.......etc....
These things are all limited by the fact that they have to conform to 12volt DC power.
By only using 12 volts,you must have a device consume more amps if it is a power hungry item...like a large amplifier or what now. You multiply the volts times 3 and you use only a third as many amps........simple really. You still wind up with the same amount of power(watts) in the end.

Looks like the C6 Corvette might be one of the first to use it.

(I'm kinda wondering what aftermarket electronis companies will do with this new power. Holy subwoofers,Batman)

And as far as valve actuation goes,people have been working to get rid of most of the valvetrain for years.

A camshaft is a HUGE compromise. You pick one set profile and have to live with it.
This basically makes the engine perform well in one small powerband. To widen this,you use displacement or forced induction,which eats gasoline and increases emissions.

Most companies have variable cams of some sort by now. VTEC,vvt-i...etc.
They use a couple cam profiles and some even have the ability to infinitely degree the camshaft,thereby giving you more profiles.

Now imagine if the valves were hydraulically actuated?
What if there was no cam and the EEC decided which profile to use at any given moment? The computer could literally select from HUNDREDS of profiles for any given situation.
This will do A LOT to minimize emissions,increase fuel economy.....and let the engine breathe like a high revving 4 cylinder when it needs to as well as giving the torque of a large displacement V8.
It lets the the engine run optimized at every throttle position and rpm. No longer will you get low end torque and sacrifice higher rpm hp....

Lotus is working on using hydraulics,some others are working on electromagnetics,some are working on pnuemnatic actuation......

Basically,they will all prolly use a valve spring to return the valve to closed position when its said and done.
If you use hydraulics or air or electricity to close the valve,they(people working on this stuff) found that it slams the valve closed too hard and sacrifices durability.......

Lotus has units that are fully running and says within 5 years they will be in production auto's easily enuff.

I won't even go into auto-ignition...hahah.
With that you will use a spark plug to start the engine and then the ignition system will just shut off as the mixture will ignite itself with compression and retained heat in the combustion chamber........much like a diesel.

This is the future of automibiles as much as a hybrid electric is.

Sorry.......was bored so felt like typing.

AkuraCLS

thats pretty cool, where'd u find the article?

astro

damn PullT, thanks for the informative write up, now I can see the implications a little bit more clearly than from Tom2's explanation...

Tom2

Yes, solenoid actuated intake and exhaust valves have been a dream of drivetrain engineers for years now.

Any engine can be optimized for power across the entire rpm range.

Electric water pumps, power steering pumps etc... are only the beginning. This will "free up" horsepower than can then be used to move the vehicle.

None of this is even possible without a big change in current electrical systems (42V).

Did anyone know that the new Saturn Vue uses "electrical steering"?

astro

wow, what if a fuse blows in the steering assembly?

VTEChump

Power = Voltage * Current
12 V * 3 A = 36 W
42 V * 3 A = 126 W



Simple......

bl^5

Saturn's been doing that since the early 90's

soopa

what determines the current?



this is a great post. good to learn something new...

anyone have links to more info?

flipwhip

oh wow, you guys' eagerness to learn. *a sing tear rolls down my cheek* here is some information taken from www.howstuffworks.com

The three most basic units in electricity are voltage (V), current (I) and resistance (r). Voltage is measured in volts, current is measured in amps and resistance is measured in ohms.
A neat analogy to help understand these terms is a system of plumbing pipes. The voltage is equivalent to the water pressure, the current is equivalent to the flow rate, and the resistance is like the pipe size.

There is a basic equation in electrical engineering that states how the three terms relate. It says that the current is equal to the voltage divided by the resistance.

I = V/r

Let's see how this relation applies to the plumbing system. Let's say you have a tank of pressurized water connected to a hose that you are using to water the garden.

What happens if you increase the pressure in the tank? You probably can guess that this makes more water come out of the hose. The same is true of an electrical system: Increasing the voltage will make more current flow.

Let's say you increase the diameter of the hose and all of the fittings to the tank. You probably guessed that this also makes more water come out of the hose. This is like decreasing the resistance in an electrical system, which increases the current flow.

Electrical power is measured in watts. In an electrical system power (P) is equal to the voltage multiplied by the current.


P = VI

The water analogy still applies. Take a hose and point it at a waterwheel like the ones that were used to turn grinding stones in watermills. You can increase the power generated by the waterwheel in two ways. If you increase the pressure of the water coming out of the hose, it hits the waterwheel with a lot more force and the wheel turns faster, generating more power. If you increase the flow rate, the waterwheel turns faster because of the weight of the extra water hitting it.

In an electrical system, increasing either the current or the voltage will result in higher power. Let's say you have a system with a 6-volt light bulb hooked up to a 6-volt battery. The power output of the light bulb is 100 watts. Using the equation above, we can calculate how much current in amps would be required to get 100 watts out of this 6-volt bulb.

You know that P = 100 W, and V = 6 V. So you can rearrange the equation to solve for I and substitute in the numbers.


I = P/V = 100 W / 6 V = 16.66 amps
What would happen if you use a 12-volt battery and a 12-volt light bulb to get 100 watts of power?


100 W / 12 V = 8.33 amps
So this system produces the same power, but with half the current. There is an advantage that comes from using less current to make the same amount of power. The resistance in electrical wires consumes power, and the power consumed increases as the current going through the wires increases. You can see how this happens by doing a little rearranging of the two equations. What you need is an equation for power in terms of resistance and current. Let's rearrange the first equation:


I = V / R can be restated as V = I R
Now you can substitute the equation for V into the other equation:


P = V I substituting for V we get P = IR I, or P = I2R
What this equation tells you is that the power consumed by the wires increases if the resistance of the wires increases (for instance, if the wires get smaller or are made of a less conductive material). But it increases dramatically if the current going through the wires increases. So using a higher voltage to reduce the current can make electrical systems more efficient. The efficiency of electric motors also improves at higher voltages.

This improvement in efficiency is what is driving the automobile industry to adopt a higher voltage standard. Carmakers are moving toward a 42-volt electrical system from the current 12-volt electrical systems. The electrical demand on cars has been steadily increasing since the first cars were made. The first cars didn't even have electrical headlights; they used oil lanterns. Today cars have thousands of electrical circuits, and future cars will demand even more power. The change to 42 volts will help cars meet the greater electrical demand placed on them without having to increase the size of wires and generators to handle the greater current.