Electric cars.

I thought I would start a new thread..because having found the data on the Tzero, it bears a bit more discussion.

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got - at an average speed of 50mph - a figure of 217Wh per mile

Now I accept that they were probably driving in the sort of way that those idiots trying to 60mpg out of skoda diesels drive..but its still a data point.

That means to achieve 500 miles range they would need just 10KWh.

This on a 200bhp sports car..

I still reckon that to get serious range at sensible power levels you need around 50KWh.

Even taking my tiddly little lithium batteries at 150Wh/kg, thats only

333kg. and about 167 liters of space. (I just measured mine. 36Wh in 120 cc of volume)

Thats a cinch to fit in a car. Under the floor. I mean a petrol tank is 60 liters in a decent one..this is not even three times that.

Add in lets say a kilowatt per kg of the rest of the power train (easily achievable) the motor(s) and control gear would weigh in around 150kg

so about 483kg for the 200bhp power train.

Thats the practicaliies

Now for fuel efficiency and economy.

Comparison with diesel at 10kw/litre

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shows that to be *as efficient* that diesel ought to be able to do a 100 miles on just two liters of fuel. In fact its more like two GALLONS showing that the diesel is, with respect to the electric car (neglecting charging and generation inefficiencies) about 27% efficient. That bears out my gut feeling that a diesel is at its very very best, capable of about 40% thermal efficiency, and is probably operating at less than 30% even in the most favourable regimes. And far far worse idling at traffic lights :-)

taking not the 200Wh/mile figure, but somethig nearer 400Wh per mile, as being realistic and figuring on an overall 80% charge efficiency, you get 2 miles per unit of electrical input. So whats that - 5p a mile worst case. At sort of off peak prices you might be down to 1.5p a mile or better.

With diesel at £3.42 a gallon and doing 50mpg, thats 6.8p a mile.

Overall energy efficiency.

If we take an average of 50% power station efficiency, 90% transmission efficiency and 80% charge efficiency (these are realistic figures, according to experience and what data I could find) and apply that to the figure of 217wh per mile, we get 36% overall losses...so 602Wh per mile is what the power station has to BURN to get the car doing its stuff.That, applied to diesel at 10KWh per liter gives us an overall 'fuel consumption' of 62mpg...on an economy run. So overallI reckon there is nothing to choose.

Charging issues

to charge 50kWh overnight in ten hours is a peak rate of 5Kw. Somewhat beyond a 13A socket, ...but NOT beyond a 13A ring, which is typically rated at 30A or 7.5kw. Its certainly less than the load a cooker spur - rated on a 40A 45A or 60A trip - could handle.

A fast charge at a service station WOULD be a challenge. If the batteries would take a half hour charge - after 500 miles you'd need that sort of break anyway - you are looking at 100KW - say 300A at mains voltages.

Chances are however in the UK that 500 miles is all you would ever need to do in a day. Keeping your 'tank full' would be basically what you would do every night.

Sadly this makes 'on street' parking a thing of the past :-) No bad thing anyway IMHO.

On street users would have to drive to Tescos and charge their once a week while they did their shopping :-)

Or get the AA out with their 400KW batteries and get a 'tankful'..or at least enough to get them to where they could charge.

Cost of cells and operations Mmm. This is the current killer. I paid about $6 per watt hour for a bargain buy. that puts the cost of the 50kWh pack at $300,000 in terms of what is currently actually in production. Say £200k. ;-)

Motors? well a halfway decent vacuim cleaner motor is about 50 quid for a couple of bhp so 5 grand should net you 200bhp of electric motors. Not an issue there.

We reckon to get 200-300 cycles out of a pack...at 500 miles range, that comes out to 100,000-150,000 miles. Acceptable. Amortise the pack cost even at 200,000 pounds, and you are up to a shade over 2pounds a mile. That is not cost effective, but its not so far outside what would be cost effective on a big luxury car (and I think that is where this sort of thing may actually come in first - not in town cars, but in big Lexus style cars, where the utter smoothness of the electric drives will be seen as a great benefit) When you consider that there should actually be - apart from possibly brake pad and tyre changes NO SERVICE COSTS AT ALL (ok, maybe a squirt of oil and grease somewhere..) it actually gets to look a bit more sensible.

Conclusions

Apart from inertia, and battery costs,nothing is stopping anyone from building a top class electric car.. the technology exists to build an electric car that would certainly perform as well as, and in many ways better than, a current state of the art diesel, with no worse overall fuel economy from oil well to street mile, and conceivably better.

It could be charged overnight, have a top speed in excess of 120mph, a performance rivalling any car in the 200bhp class, and have a 500 mile range driven reaosnably gently (and with the whole motor system under computer control, thats nothing more than setting a switch..)

Its oin-street pollution would be zero, and due to the fact that the power stations can certainly act more realistically to sink carbon and have higher thermal efficiencies than a car can, its overall pollution would be less.

If nuclear power to generate electricity comes along - or other green energy generation methods - it has to be seen in a new light: How does it compare with

- biofuels

- nuclear electric to hydrogen in IC engines

- nuclear electric to hydrogen in fuel cell electrics

It matches biofuels directly in the same way as burning diesels does now. I.e. not a lot in it. Once you burn biodiesel you end up with the overall

20-40% efficiency. The more efficient power station is offset by the losses in transmission and charging.

It knocks the spots of hydrogen, because fuel cell efficiences are simply limited by the same sorts of efficiency limits that limit heat engines. With hydrogen you get a double whammy - creating it is inefficient and so is burning it. If we didn't have suitable batteries, it woild be the only answer ...but we do..

Batteries are simply the best way to store electrical energy bar none in terms of efficiency. And lithium batteries are small enough and light enough for all but extremely high power or long duration use. I.e. not for boats, and not for aircraft Well not airliners. I reckon that if it hasn't happened already, the first man carry ing microlight or glider powered by lithium batteries is months away only.

Why aren't peole doing it?

I think two reasons

Firstly, the 'green' tag is flawed unless the electricity comes from other than fossil sources. As I feel I have demostrated that the overall fuel efficiency is similar to class diesel car. (performance is BETTER though ;-))

Cost. The batteries are simply way too expensive right now. Ther is however absolutely no reason why they should be...there is nothing intrinsically expensive about a lithium polymer battery. In massive volumes, one might expect them to be cheaper than lead acid batteries ultimately.

This is why I think Tzero have the better approach, and the Priuset al are deeply flawed from a marketing perspective. Electric cars have not actually

- until mated with a nuclear generating backbone - got any green points to make. What they do offer, is extaordinary peak power to weight ratios, but good econonmy at cruise, coupled with almost vibration and noise free operation. That puts them straight into the luxury market.

ULTIMATELY when the batteries are cheap you wiill see them being turned out as mass market shopping trolleys, but not yet. The high level of development money needs to be recouped in more profitable markets.

Reply to
The Natural Philosopher
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the M6, M1, M62, M25 et al at all?

Chris.

Reply to
mcbrien410

NO. just just don't choke in them.

Reply to
Doctor Drivel

This is three times the consumption you posted in the other thread.

I make it 10 times that.

There is the issue of installed battery capacity being different from acceptable depth of discharge. When we looked at battery storage for a remote site the capital charges on the battery were twice the cost of the generated electricity's fuel portion, which itself was about the same as grid power.

I'm not knocking the concept and I will look at the rest of your post again but am pushed atm.

AJH

Reply to
AJH

Oh I nearly fell asleep after reading that message. Can you get to the point in a few lines ? Stick to a diesel car, far more economical than running an electric one.

Reply to
gtl

consumption'

Look at:

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Toshiba battey can be charged to 80% in a few minutes.

Also the smoothness and silence which a diesel tractor like engines just can't get. Then servicing that costs of a small check and check the brakes and running gear. Cheaper to service and far more reliable. The car will also be much better designed as no large engine/transmission.

I think you are wrong. The marketing is right for the time. Toyota, and others, would not put on a mains charging plug as this would give it the wrong image. That is changing. What concerns people is having a flat battery miles from nowhere, and charging from the mains (fine if you have a garage or car port). There are no few minute recharge stations about yet (the Toshiba battery). Many want the hybrid with larger batteries and a mains charger as an alternative. A Califorinan company has installed a charging point and larger Lith Ion batteries and getting 120mph (US), which is more in UK gallons. The overnight charging is very cheap.

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cars would benefit from a small high efficient free wheeling piston (the only moving part) Stirling engine that charges the batteries, when they get to a certain low level. A Steam Cell could also be used for charging.
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A Stirling or Steam Cell is very small.

They do not pollute at point of use. That is a GREAT advantage. Towns and cities, where millions of lungs are exposed, are instantly cleaned up.

You are way behind. Mitsubishi are developing EV cars right now. The batteries will be in place by the time their cars come to market in 4 to 5 years time.

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is an all new dedicated electric in design of body and mechanicals to take advantage of the technology.

Reply to
Doctor Drivel

Nope. Toyota Prius knocks them for 6.

Reply to
Doctor Drivel

Until you want to heat the car, and have more than two people in it.

No, it wouldn't be.

Because there are no advantages over similar cars with IC engines.

Reply to
Nick Finnigan

Electric motors give off heat. This can be harnessed.

It would. Clean at point of use.

You are confused. Please read all again.

Reply to
Doctor Drivel

Don't underestimate electric vehicles. Batteries have come a long way, and the laest technology has no relatio to the outdated lead/acid battery in your car. In addition to the extened range, Toshiba recently announced Lithium batteries that can charge to 80% in one minute, and fully charge in

  1. Electricity is a way more efficient way of generating motion than petrol or derv. Using petrol or derv to make steam, turn a generator, and put the electricity in a car is more efficient than putting petrol or derv directly into a car. Electricity can also be generated from motion of the car itself, regenerative breaking, which petrol or derv can't do. Electric cars are vastly superior to petrol in maintenance costs. They require no transmissions, no cooling systems, no oil changes, and with periodic battery replacements, will last forever. Then the ride: smooth, silent, vibration free. That alone is a great environmental plus.
Reply to
Doctor Drivel

Check out

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miles on Lith Ion batteries and circa $40,000.

"Target Price: $38,000 to $45,000

The Electrum Spyder is an exciting 2 passenger convertible all electric freeway flier that will be available in a limited production. Powered by a

288 vdc system, the Spyder provides an effective range of up to 150 miles at a top speed governed at 80 miles an hour on a full charge using nickel zinc batteries, standard in all of our vehicles. As with all of our Electrum series the Spyder is available with optional lithium ion batteries with a range of up to 300 miles on a single charge."
Reply to
Doctor Drivel

The message from "Doctor Drivel" contains these words:

You can't have it both ways Dribble. If electric motors were 100% efficient there would be no waste heat at all.

With hub mounted electric motors recovery of any waste heat would be a problem and unsprung weight is traditionally considered undesirable so why are hub motors the obvious choice?

To change the subject somewhat I remember reading an article in a technical journal back in 1961 that suggested that hydraulic motors were the way to go but that never caught on either.

Reply to
Roger

As AJH pointed out, its 10x that, which takes you upto 3 mill per car. Thats why I'm not buying one!

You said fuel economy was comparable, but you neglected the main route of fuel consumption: not road fuel, but the fuel used in production. To explain. Why do the batteries cost so much? The answer is because it takes a huge amount of energy to get them produced. (That includes production of the materials the batteries are made from.) While its not exact, cost is a rough guide to energy use. If something takes me 1000 barrels of oil and 6 months to make, its gonna cost. The 6 months means

6 months of supporting a human being, and that comes down to energy. We need money to buy energy firectly, and money to buy things that took energy to produce, eg food, clothes, etc etc.

In short, the whole electric car system is energy hungry. It thus has nothing to offer over fossils.

Its very hard to beat fossil fuel because it is so very available, in such huge quantities. Its cost is therefore relatively low.

NT

Reply to
meow2222

Roger, keep you hand on your washing machine motor for while. Or keep it there for a few hours.

One inboard motor can be utilised with a small diff. More Rogerness to follow...

Yes that was Rogerness all right.

Reply to
Doctor Drivel

On Tue, 29 Nov 2005 21:18:42 -0000, "Doctor Drivel"

A 4 pack of 40 litre AA Duracells please.

Reply to
Matt

And in summer you melt

Reply to
Matt

Lord Hall, are you into electric cars now? Do you think a Makita would propel one?

Reply to
Doctor Drivel

Lord Hall, do you keep your heater on full in summer in your appalling car?

Reply to
Doctor Drivel

I'm not Lord Hall. But in answer to your question, no I drop the top or use the air conditioning or when I feel like it do both.

Reply to
Matt

Lord Hall, so why would you keep the heater on in an electric car in the summer?

Reply to
Doctor Drivel

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