Why do electric powered automobiles need to be so complicated?

Google was not invented for you to ask wordy twat questions of us demigodz

OK, I'm speaking for the others.

As the son of my Dad I can guarantee that you are wasting your time.

Kindly f*ck off until you have figured out how to do fusion the simple way like what I have. No one will pay bugger all interest anyway.

Footnote, Dad said Whoops and then rolled around larfing.

These things I understand.

DNA

Sno-o-o-o-ort !-)

...Jim Thompson

There are much information on DIY electric cars on the net. Use Google and search for "electric car +DIY", without the quotation marks.

It is a real education.

Have fun!

Rolf

Here is one of the better explained conversions, that explains why it is rather complicated and expensive. Link:

Rolf

As far as I know you don't. You will need them on a hybrid though which may be what you're thinking of.

No.

Not sure if it's the *same* but they can do this very well.

It can certainly slow it.

In any event would you feel safe in a car without brakes ?

This is already done. See 'regenerative braking'.

Toys aren't the same.

Graham

Actually, an electric motor will have its greatest torque when it is stalled. You know that a motor is the same as a generator, well when the motor is running it generates an EMF which opposes the applied EMF. In other words, the generated voltage is subtracted from the applied voltage, this will reduce the current flowing in the coils of the motor and therefore the torque.

I don't see why electronic speed control would be a problem

Regenerative braking is certainly be possible. However, it may be wise to include some additional system for safety.

I doubt regenerative braking could stop a car as quickly as a conventional braking system. Also remember that the regenerative braking would only act on the driving wheels, which may not be all four.

You would still want a brake pedal even if the actual braking was done via the motor as you would need some way for the driver to tell the car to break and how hard. You probably wouldn't want the car to do emergency stop every time you took your foot off the accelerator.

Petrol (gasoline) has energy of about 33 MJ (Mega Joules) per litre, or about 125 MJ per gallon. So a 10 gallon fuel tank will hold approximately 1250 MJ of energy. Now internal combustion engines are not very efficient, lets assume 20% of this energy is usable, we then have ~250MJ of usable energy in a car fuel tank.

Therefore:

The energy density of NiMH batteries is ~70Wh/Kg so we would need ~1000 kg = 1 tonne of batteries to hold as much usable energy as 10 gallons of gasoline. Even taking into account the poor efficiency of an internal combustion engine.

I think this is the real problem with electric vehicles.

Regenerative braking would make the braking asymptotic, which isn't much good when a kid is in the road in front of you. Four wheel braking could be accomplished by four wheel motors, but now we start to get complicated. First, the braking characteristics have to be right when cornering as much as when stopping. Also, when cornering, the wheels have to go at different speeds (thats what the diff is for on an IC car).

So the drive has got to be coordinated with conventional brakes. And it's got to be coordinated with the steering. That's why electric powered automobiles need to be so complicated.

Paul Burke

Good point. The braking effect would be limited by motor power. Just compare acceleration with much the more rapid braking and it becomes obvious why it's not practical to use this alone.

Graham

Clutch/transmission, because accelerating requires much greater force than does overcoming aerodynamic and other losses at cruise. You either start moving very slowly (which most people don't like to wait for), or you shift gears as you get to higher speeds.

Mostly true. But trains don't have to accelerate quickly.

Which is easily handled by varying the applied voltage with the drive frequency, and is already done in many variable speed motor drive applications.

You don't need as many gears, but without them, you either install a gigantic motor to handle accelerating torque (and then is grossly overpowered for its use), or you accept very slow acceleration.

It isn't, and is in fact required for practical use.

John Perry

Thanks to all who replied! Other than the a-hole who thinks too much of himself. Nice to know that he/she only represents a small part of this group.

But let's not forget that the controller is switching hundreds of amps so while not a problem, it's not trivial either (mentioned since the op was asking why ev's are so complicated).

Ken Muldrew snipped-for-privacy@ucalgazry.ca (remove all letters after y in the alphabet)

A little research will tell who to ignore on which topics. Mr. Thompson, for example, (and I know he's not the a-hole you had in mind) is a whiz of an engineer but is, er, "old-fashioned" on social issues.

A little further research will convince you that this is actually a social/pilitical issues discussion group among engineers.

"old-fashioned"? Am I now? I'm probably as liberal as they come on "personal" choice issues. I'm even for freedom FROM religion. But I AM a HAWK... kill or be killed.

Illegal immigration? Nothing that a few gunship helicopters couldn't cure in a few hours.

Indeed ;-)

...Jim Thompson

Lets make all immigration illegal. But if you are shrewd enough to come here and land a job for a year, you get instant citizenship. That way we skim the best from other countries, and leave them with the bad end of the gene pool.

Luhan

Too easily scammed.

John

Thats the point, we want the ones who show initiative. We want the scammers, schemers, and others who just dont go allong with the status que - exactly the type of people who started this country in the first place. Or do you suggest going back to British rule?

Luhan

Nah, you can be honest and still show initiative--most of the crooks I've known (several to many) were crooked because they were lazy or greedy, not because they were smart. Of course, if the scammers and schemers all promise to live in your neighbourhood, I'll be less worried about it.

Cheers,

Phil Hobbs

Scan back yourself and you'll see I specified holding a job here - not being a crook.

This is really my commentary on the issue of 'illegal' aliens. I just have no problem with anyone who comes here to work. Friends of mine often hire guys right off the local street corner here when they need some heavy work done. Far as I have seen, they are really good workers.

Luhan

But they're sinking the health care systems in places like Yuma, AZ.

...Jim Thompson