backtop


Print 86 comment(s) - last by 91TTZ.. on Sep 20 at 9:40 PM


Audi e-tron
Concept has four electric motors and a single battery pack

The world of electric and hybrid vehicles is progressing and growing at a rapid pace. While most people still think of hybrids and electric vehicles as low performance machines, there are an increasing number of high-performance electric vehicles being unveiled.

The first high performance EV was the Tesla Roadster with good performance thanks to the impressive torque of the electric motor. Audio has unveiled its latest concept car at the International Motor Show in Frankfurt called the Audi e-tron which just so happens to look like an electrified Audi R8.

The most impressive feature of the concept isn’t just its all-electric power train, but its tremendous amount of torque. Audi claims that the e-tron has a torque rating of  3,319.03 lb-ft. All that torque is generated by four individual electric motors situated at each wheel allowing the vehicle to be all-wheel drive.

The car has a total of 313 HP and promises to hit 60 mph in about 4.8 seconds. A more impressive number is that the car can go from about 37 mph to 74 mph in only 4.1 seconds. The all-electric range for the lithium-ion battery pack is 154 miles.

The EV is a large beast at 3,527 pounds and it measures in at 74.5-inches wide x 167.72-inches long and 48.43-inches tall with a wheelbase of 102.36-inches. The massive single battery pack alone weighs 1,036 pounds.

"We are trying to find a concept that requires no compromises," says Michael Dick, Member of the Board of Management of AUDI AG, Technical Development. "Electromobility means more to us than just electrifying conventional cars. Instead, we are dedicated to a holistic approach to all aspects of the topic."

Audi's American President called potential Volt buyers idiots not long ago and then quickly claimed he forgot what he said. There was only speculation surrounding the Audio EV concept at the time the comments were made.



Comments     Threshold


This article is over a month old, voting and posting comments is disabled

<Drool>
By Aeternum on 9/15/2009 10:51:13 AM , Rating: 2
LOL who needs a Kenworth now? Tow semi-trailers in style :)
J/K. Gotta say other electric vehicles are smokin fast without over 3k torque so this must be a 'cause we can' thing. Seriously though would love to have one. Seems electric cars are coming along nicely now.




RE: <Drool>
By guacamojo on 9/15/2009 11:04:30 AM , Rating: 3
3,000 ft-lbs of torque is useless in a sports car. How do you couple it to the road? The car will just sit and burn rubber for a while, but you can do that with far less torque.

Torque is great when you're pulling a boat up the ramp, but I don't think you're going to do that in your E-tron.

I'd bet that they got the torque for free when they spec'd the 300 hp electric motors, and the statistic sounded impressive.


RE: <Drool>
By Spuke on 9/15/2009 11:46:54 AM , Rating: 2
quote:
3,000 ft-lbs of torque is useless in a sports car. How do you couple it to the road?
With todays tires, you don't. The torque would be severely limited in reality. BTW, I heard rumors of this car for the past two months or so. The rumors were an actual electric R8. But it turns out it's just a concept car with an R8-like body.


RE: <Drool>
By theapparition on 9/15/2009 3:16:32 PM , Rating: 4
Not at all true.

Take an old C5 Corvette, with only approximately 360ft-lbs. Multiply that by 3.06 for first gear and 3.42 for differential gear. That's a torque multiplier of 10.46 which is a total of ~3800ft-lbs at the rear wheels.

Not at all much different. Also explains why 0-60 times are so similar to a C5. A C6 would even be higher in the 4500ft-lbs range.

Quite a bit of difference between engine torque and wheel torque.


RE: <Drool>
By Spuke on 9/16/2009 11:38:06 AM , Rating: 3
quote:
Quite a bit of difference between engine torque and wheel torque.
Then what does a Dynojet measure?


RE: <Drool>
By theapparition on 9/16/2009 12:57:10 PM , Rating: 2
Have you ever run a Dynojet?

I have.

You have to enter those parameters in when stating the pull. For automatics, it uses the ODB port to determine which gear you're in.

When an engine is rated for torque and power, per the SAE standard, it is tested on an engine stand, not in a car.

It is a misnomer that when gearheads (like myself) rate cars with rwhp and rwtq, it is really engine hp and torque accounting for drivetrain losses.


RE: <Drool>
By Zoomer on 9/16/2009 6:30:23 PM , Rating: 2
Since the motors are at the wheels with no drivetrain, wouldn't engine torque = wheel torque?


RE: <Drool>
By theapparition on 9/17/2009 7:45:38 AM , Rating: 2
No. The wheel torque in a car with an ICE will be approximately 10x that of the engine itself. (All depends on the gearing in the transmission and differential, but 10x is decent 1st gear average.)

Wheel torque in a car with a motor mounted in the hub will be equal to the torque rating of the motor.

They are making this out to sound like something special, when it's really not. Where it does differ is the motors delivery of torque. Full torque is available at almost 0 RPM, while an ICE reaches max torque at a much higher RPM. That is why it is essential to drop the clutch (or use a high stalled auto) at the RPM where most torque is delivered for the best launch.


RE: <Drool>
By Spuke on 9/17/2009 1:31:20 PM , Rating: 2
quote:
Have you ever run a Dynojet?
I have not but that's why I'm asking. When you get a graph from a dyno, the torque rating isn't 4500 lb-ft (or whatever ridiculously high number). Maybe this discussion of torque multiplication is confusing me but I always thought that the actual torque number when a car is dyno'd was the result of the gearbox multiplication. My car would make say 220 lb-ft at the wheels on a Dynojet not 3000 lb-ft.


RE: <Drool>
By theapparition on 9/17/2009 3:58:35 PM , Rating: 2
No. It measures that high number and then back-calculates through input parameters to determine theoretical engine torque.

That's why I stated before the the concept of rwtq is flawed, yet often quoted (hell, even by myself). Yet what is being delivered to the tires is quite different.

In fact, dynojets don't even measure the engine RPM on older cars, rather use the tire diameter and tire RPM to generate those graphs.

For a simple ballpark figure, take the engine power and divide it by tire RPM. Power = Torque * RPM/5252.

So if an engine is developing 300hp at 6000RPM, and there is a 10x reduction through gearing, than the torque being delivered is 300hp*5252*(6000RPM/10) = 2626ft-lbs.

Pretty simple, and also requires that a dynojet knows what size rear differential and what gear the car is being operated in. Otherwise the results are junk......and also how some unscrupulous tuners like to improve thier results.


RE: <Drool>
By AbsShek on 9/15/2009 12:05:44 PM , Rating: 3
Looks like it will need the torque to lug around the already heavy battery and motors... add in a boat and ur screwed...

pretty impressive acceleration times for such a heavy car though... i guess that's where the torque comes in...


RE: <Drool>
By andrinoaa on 9/15/2009 5:34:34 PM , Rating: 2
Maybe, you won't afford to buy one unless you sell the boat.
If you can afford one, you can afford a towing vehicle too! Yada yada yada


RE: <Drool>
By scrapsma54 on 9/15/2009 12:11:31 PM , Rating: 2
I am sure audi is designing a nice little independent variable gearboxes for the sunnuva guns, if their is such a thing as indestructible.


RE: <Drool>
By mcnabney on 9/17/2009 10:04:25 AM , Rating: 2
You do understand that having independent motors on each wheel eliminates the gearbox entirely?

I believe the Tesla only has two forward 'gears' and a reverse. You actually don't even need to use the second forward 'gear', since it is technically not a gear. The article should have also mentioned that by adding a heavy battery and four light motors you can also remove a heavy engine, transmission, axles, exhaust, fuel tank, and fuel weight.


RE: <Drool>
By Trippytiger on 9/19/2009 3:05:53 PM , Rating: 2
The Tesla Roadster is actually down to one gear now. The ratios they wanted to use in the transmission were very far apart, which caused components to break. So they settled for water cooling the electric motor to solve the overheating problem that the two-speed gearbox was meant to fix in the first place.


RE: <Drool>
By markitect on 9/15/2009 1:21:03 PM , Rating: 2
your missing the fact that if the engines are per wheel there is little or no transmission, Your car transmission probably multiplies your torque by 3-5 times what the engine is rated at when your in first gear.


RE: <Drool>
By theapparition on 9/15/2009 3:18:27 PM , Rating: 2
Engine and differential in a modern high performance car is closer to 9-12x multiplier.

So even more reinforcement.


RE: <Drool>
By Chemical Chris on 9/15/2009 1:31:18 PM , Rating: 5
quote:
37 mph to 74 mph in only 4.1 seconds

That is what torque gives you, 'passing power'. Instantaneous power at any rpm.
Also, with so much torque, less mechanical torque multiplication must be used, allowing the motor/gears to be smaller and simpler, important with a motor and gear pack at each wheel.
oversimplified idea: If you had 300lb-ft and and 300hp, you would need gears to get the power to the road. with 3000lb-ft and 300hp, no gears would be necessary. Remember horsepower = (torque * rpm) /5252. So, if two engines have 300hp, but one has 10x the torque, it will have 10x the power per rpm/would have fewer rpm's to go through to get to peak power. The current R8 has a first gear ratio of 4.37, sixth is 0.93, final drive is 3.71. Torque is 317lb-ft from 4.5-6Krpm. Therefore, the wheels see 5139lb-ft in first, 1093lb-ft in sixth.
Im starting to rant, so Ill end now...

ChemC


RE: <Drool>
By fic2 on 9/15/2009 1:33:16 PM , Rating: 2
quote:
3,000 ft-lbs of torque is useless in a sports car. How do you couple it to the road? The car will just sit and burn rubber for a while, but you can do that with far less torque.


It's pretty easy to program the "gearing" so that the tires don't burn rubber. Tesla already does this. They take apply max power until the tires slip, then back off. Rinse, repeat.


RE: <Drool>
By Spuke on 9/15/09, Rating: 0
RE: <Drool>
By Amiga500 on 9/15/2009 2:23:32 PM , Rating: 2
Read about gearing and torque multiplication.


RE: <Drool>
By theapparition on 9/15/2009 3:27:12 PM , Rating: 3
No clue where you came up with this number.

Not to beat a dead horse, but that 3000ft-lbs is divided by each tire, or 750ft-lbs/tire.
A C5 would have approx 1800ft-lbs to each of the rear wheels (assming posi traction), and while you can get some slippage in a base C5, it is minimal and well within the capability of the stock run-crap tires they used to put on there. Add decent rubber, and you're fine. A LS3 C6 would even put more down, approx 2200ft-lbs per tire, and that is fine as well.

Go to R compound tires and even 4000ft-lbs is a non-issue at the track. Take that a step further to wide slicks and that number goes up further. My C5 drag car puts out 9000ft-lbs at the wheels! Hoosier slicks have never disappointed me.

So net effect is this car would actually be slower than most modern Corvettes, Porshes, and even ricer STi's while tires wouldn't even be an issue. A fact that the released performance numbers confirm, despite the sensationalist headline.


RE: <Drool>
By Spuke on 9/16/2009 11:39:38 AM , Rating: 2
quote:
A C5 would have approx 1800ft-lbs to each of the rear wheels
Again, if a C5 has 1800 lb-ft of torque at the rear wheels, what does a Dynojet measure?


RE: <Drool>
By Spuke on 9/16/2009 11:41:34 AM , Rating: 2
quote:
Go to R compound tires and even 4000ft-lbs is a non-issue at the track. Take that a step further to wide slicks and that number goes up further.
I'm not talking about specialty tires, I'm talking about tires are put on street cars from the factory which 99.9% of the population will be using. A set of Michelin PS2's ain't putting down 3000 lb-ft to the pavement without electronic nannies.


RE: <Drool>
By theapparition on 9/16/2009 1:06:49 PM , Rating: 2
Michelin P/S 2 (great tire BTW) come in various sizes, including 335 width. Do you actually mean to imply that a P/S 2 in a 335 coudn't handle more than a similar 195 width. There are quite a wide variety of P/S 2 tires sold on cars, but since we are talking about sports cars, yes, I believe they are 335 P/S 2's on the ZR1. So a blanket statement that 99.9% of tires couldn't hold xxxx torque is pretty misleading.

Weight of the car, contact patch, and rubber compound all contribute to the amount of friction force that the tire is capable of.

Now, keep in mind, that torque I talked about is at the shaft, you now have to divide that by the moment arm (also known as tire radius) to find out what the pavement/rubber interface force will be.

You can disbelieve all you want, but fact remains that quoted performance numbers match closely towards conventional gas engine cars of 10x "less" rated torque.


RE: <Drool>
By Spuke on 9/17/2009 1:36:31 PM , Rating: 2
quote:
You can disbelieve all you want, but fact remains that quoted performance numbers match closely towards conventional gas engine cars of 10x "less" rated torque.
it's not about disbelief, it's about you guys not explaining yourselves. I'm asking the questions to get an explanation. When I take my car to the dyno, the sheet doesn't say I have 3000 lb-ft it says I have 220. Yet you guys are saying that a C5 actually puts down X 1000 lb-ft of torque to the road. If that is so, what does a Dynojet measure?


RE: <Drool>
By theapparition on 9/17/2009 4:03:07 PM , Rating: 2
Answered above.


RE: <Drool>
By 91TTZ on 9/20/2009 9:35:53 PM , Rating: 2
quote:
When I take my car to the dyno, the sheet doesn't say I have 3000 lb-ft it says I have 220. Yet you guys are saying that a C5 actually puts down X 1000 lb-ft of torque to the road. If that is so, what does a Dynojet measure?


I think that the majority of people replying in this thread have little to no knowledge of how cars or dyno's work.

I'll do my best to answer your question:

When you dyno your car they make you put it in 4th gear to do the pull. They do this to get it as close to a 1:1 ratio through the tranny as possible. From the spark plug clamp they know what RPM your engine is turning, and the dyno computer already knows what RPM the drum is turning. It's all math from there. They aren't going to show you a 10x multiplication because your ratio is about 1:1 during the pull. In addition, even if you pulled it in 1st gear and you had a 10x gearing multiple, the dyno computer would divide it by some ratio between engine rpm and drum rpm.


RE: <Drool>
By 91TTZ on 9/20/2009 9:40:59 PM , Rating: 2
quote:
When I take my car to the dyno, the sheet doesn't say I have 3000 lb-ft it says I have 220. Yet you guys are saying that a C5 actually puts down X 1000 lb-ft of torque to the road. If that is so, what does a Dynojet measure?


I think that the majority of people replying in this thread have little to no knowledge of how cars or dyno's work.

I'll do my best to answer your question:

When you dyno your car they make you put it in 4th gear to do the pull. They do this to get it as close to a 1:1 ratio through the tranny as possible. From the spark plug clamp they know what RPM your engine is turning, and the dyno computer already knows what RPM the drum is turning. It's all math from there. They aren't going to show you a 10x multiplication because your ratio is about 1:1 during the pull. In addition, even if you pulled it in 1st gear and you had a 10x gearing multiple, the dyno computer would divide it by some ratio between engine rpm and drum rpm.


RE: <Drool>
By Spuke on 9/17/2009 1:43:20 PM , Rating: 2
You said,
quote:
Go to R compound tires and even 4000ft-lbs is a non-issue at the track. T

I said,
quote:
I'm not talking about specialty tires, I'm talking about tires are put on street cars from the factory


Michelin PS2's are regular street tires and I have yet to see a twin turbo Viper with 1000+ lb-ft of torque NOT smoke a set. I have yet to see a Solstice with 300 lb-ft NOT smoke a set. FACT, todays STREET tires can't hold the torque that this Audi will will be putting down, especially at that super low rpm, without electronic nannies.


RE: <Drool>
By theapparition on 9/17/2009 4:01:39 PM , Rating: 2
If you put a wide enough tire on any car, it will hold fine.

I only took issue with your 280ft-lb comment that seemed to be pulled from air. Can you supply some sort of data that supports a street tires limit of grip at 280ft-lbs. If not, than admit it was just a WAG.


RE: <Drool>
By zephyrprime on 9/15/2009 5:51:41 PM , Rating: 2
quote:
I'd bet that they got the torque for free when they spec'd the 300 hp electric motors, and the statistic sounded impressive.
Probably. All the EV's of the future will have super high torque by modern standards. This Audi is leader of the pack for now but I remember reading an article just the other day about a new electric motor design that doubles torque.


RE: <Drool>
By MrBlastman on 9/15/2009 12:10:48 PM , Rating: 1
What is more amusing (I got this equation from my brother who is a car mechanic), is this torque figure is at an absurdly low RPM--495.29 RPM to be exact.

You can calculate it yourself:

313 HP * 5252 / 3319 = 495.29.

So, the torque might help it get off the line but the thing is a porker at 3527 lbs and with only 313 HP it explains why the 0-60 time is so mediocre with all that torque (that and it is very low end torque).

The thing that bothers me the most though is the independent electric motors, one for each wheel. That REALLY bothers me. If you are say going for a mountain run, or on the track and are in a tight turn (say a sharp one or a set of esses) and one of your motors happens to burn out due to the stress induced from the load on one of the wheels... You are going to go right off the side of the cliff or off the track into the wall (or another car).

Thanks Audi for the idea, I think I'm going to pass on this concept for now. Granted it gives higher efficiency due to being afforded no driveshaft, but, I'd rather take a traditional driveshaft/multi-differential design any day to give me more safety rather than taking that sort of risk. Sure, the odds might be low, but, I'm essentially doubling my risk for that type of catastrophe (as the risk already exists for a tire blowout). With a single engine the car would coast to a stop (though the weight bias would be changed depending on the acceleration which might cause a spin-out), I suppose though it depends. The risk is less however since there is one engine rather than four plus the individual wheel strain would be somewhat mitigated.


RE: <Drool>
By ice456789 on 9/15/2009 12:16:38 PM , Rating: 3
This may be a stupid question, but does RPM apply on an electric car the same way it does on a normal car?


RE: <Drool>
By threepac3 on 9/15/2009 12:50:10 PM , Rating: 2
They still do but aren't exactly relative to internal combustion engines.


RE: <Drool>
By Spuke on 9/15/2009 1:30:42 PM , Rating: 2
quote:
They still do but aren't exactly relative to internal combustion engines.
RPM is RPM. Electric motors don't have some special RPM. Electric motors spin, combustion engines spin.


RE: <Drool>
By JediJeb on 9/15/2009 2:54:16 PM , Rating: 3
quote:
RPM is RPM. Electric motors don't have some special RPM. Electric motors spin, combustion engines spin.


True, but there is gear reduction with regular drivetrains, but if the electric motor were coupled directly to the wheel with no gear reduction then they would spin over 3x slower than the IC engine would to produce the same speed. So if you are turning 1800rpm with an IC engine in your car now and you have enough torque to do a direct drive set up with the electric motor then it only needs to turn at 600rpm to make the same speed, and many cars only turn 1800-2200rpm at 60mph.

Another thing to consider is this is using 4 motors, if the torque is total then divide by 4 and you get the torque at each wheel. With all wheel drive it takes more torque to break traction since you have less to push against than when you have two wheels just sitting there holding you back somewhat.


RE: <Drool>
By Spuke on 9/15/2009 3:24:32 PM , Rating: 2
quote:
Another thing to consider is this is using 4 motors, if the torque is total then divide by 4 and you get the torque at each wheel.
Ah, you are right. Didn't think of it that way.


RE: <Drool>
By waykizool on 9/15/2009 1:44:34 PM , Rating: 2
No. Electric motors have max toque for the amount of current that is being applied, when it is applied. IC's always have toque as well, but it is not max until it hits the RPM range that is tuned to make max toque.


RE: <Drool>
By scrapsma54 on 9/15/2009 12:23:04 PM , Rating: 1
Sure audi may not have come up with it, but having an electric system has so much more potential to reduce fatal accidents. Think less sensors, less mechanical parts.
There is room for way better timings than on a mechanical system, and easier management of each motor.
I may not be an expert on electric vehicles, but who is right now?


RE: <Drool>
By jlips6 on 9/15/2009 12:43:33 PM , Rating: 2
http://endless-sphere.com/forums/

The guys on these forums are amazing. I highly reccomend visiting, even if you don't post. A great place to educate yourself about the practical application of electrical motors.


RE: <Drool>
By Spuke on 9/15/2009 1:32:11 PM , Rating: 2
quote:
http://endless-sphere.com/forums/
Is this a technical forum or some social/political forum?


RE: <Drool>
By jlips6 on 9/15/2009 4:35:08 PM , Rating: 2
I would say it's about 80% technical. they have special forums for off topic stuff (like politics) that I don't go to. Just stick to whatever topic it is you want to learn about (provided it has to do with electrical technology). Just visit the website, the homepage has a list of forum topics. Fantastic people there.


RE: <Drool>
By Spuke on 9/16/2009 11:42:35 AM , Rating: 2
quote:
I would say it's about 80% technical. they have special forums for off topic stuff (like politics) that I don't go to.
Thanks much, I'll check it out.


RE: <Drool>
By foolsgambit11 on 9/15/2009 12:28:00 PM , Rating: 2
It's pretty trivial to program the complimentary motor to stop if one fails - i.e., if the passenger side front died, the driver's side front could turn off as well, yielding a RWD car instead of AWD. Or a FWD, if one of the rear motors died. And you gain redundancy because of it. Instead of only one motor/engine dying to leave you stranded, it would take two.


RE: <Drool>
By scrapsma54 on 9/15/2009 12:34:41 PM , Rating: 2
But on only that, but adjust power to the outside tires around curbs.
Lets not forget regen braking on all 4 motors, either.
All the ideas on this independent drive train, just driving me nuts


RE: <Drool>
By MrBlastman on 9/15/2009 12:37:36 PM , Rating: 2
Limited slip differentials already do this mechanically. I suppose you could tie a sensor to have the wheel motors go out in pairs but it still bothers me that the odds of a single motor failing is quadrupled though the odds of total failure are halved (to be fair--assuming you need two motors to propel a set of wheels).

Either way, it sounds awfully expensive to me in terms of maintenance and repair costs. For the time being I'm going to continue to stay away from anything that is VW/Audi. They just tend to over-complicate things.


RE: <Drool>
By scrapsma54 on 9/15/2009 1:47:40 PM , Rating: 2
The limited slip differential does its job to the best it could do, but as software gets better and better, I can only see that having an independent motor system (if they are independent) can only be safer since on the fly failure detection is possibility.
If it isn't independent drive train, then failure of one motor isn't so bad, but I would imagine all that uneven torque would twist the body.


RE: <Drool>
By MrBlastman on 9/15/2009 1:58:46 PM , Rating: 2
Sure, the technology could be nifty indeed. I'd rather the car manufacturers stick to KISS (Keep it Stupid Simple) though if at all possible--doing so reduces potential time in the shop for repairs and maintenance.

Remember, just because it is electrical rather than mechanical does not make it less prone to faults. I remember our families 82 Cadillac Seville (leave out American car jokes), it was cutting edge with all the latest electronic gadgets and gizmos. The thing was always breaking down, and about 80% of the time it was due to electrical related malfunctions.

The more complex you make something, the more prone it is to being problematic. Sometimes a simple but practical design is better than a complex and elegant one.

In this car's case, it isn't twisting the body that is the problem if one engine were to fail, it is what happens to the weight distribution due to the uneven power output. If you're in a tight turn pushing the limits, any unintended change in weight bias to the traction can lead to potentially awful results. This is why autocross/track racing is so fun and exciting at the same time. There's a lot more to it than just turning your wheel and stepping on the gas. Throttle control is equally as critical as when you turn or brake.


RE: <Drool>
By rcc on 9/15/2009 2:23:57 PM , Rating: 2
If you're running a standard IC powered car and you get into the same situation, pressing hard in the turns, and your engine sputters or dies at the wrong time, you are in the same boat, or ditch.


RE: <Drool>
By Mr Perfect on 9/15/2009 2:35:25 PM , Rating: 2
Electric drive might make that bit more complex, but I bet the rest of the car's systems will get a lot simpler. There probably won't be an alternator/starter, fuel pump, separate brake system, transmission(?), driveshaft and maybe even no radiator/cooling loop.

It's not that ICEs are simple, they're just routine. :)


RE: <Drool>
By Spuke on 9/15/2009 3:39:08 PM , Rating: 2
quote:
There probably won't be an alternator/starter, fuel pump, separate brake system, transmission(?), driveshaft and maybe even no radiator/cooling loop.
LOL! Yeah those parts are SOOOOO complex. Sorry but the simplest thing in an electric car will be the motors themselves. Everything else will require a EE degree.


RE: <Drool>
By TomZ on 9/15/2009 4:49:31 PM , Rating: 3
The motors are also pretty sophisticated - probably also requires an EE degree to understand as well.


RE: <Drool>
By Spuke on 9/17/2009 1:45:04 PM , Rating: 2
quote:
The motors are also pretty sophisticated
What's sophisticated about a bunch of wires?


RE: <Drool>
By scrapsma54 on 9/15/2009 8:51:07 PM , Rating: 2
Well, I think the cooling part might be necessary, It does take a lot more to burn, but once those cells start boiling the whole car is going to be melted into the cracks on the road even if you extinguish the flames or not, lithium can self ignite in water.


RE: <Drool>
By Titanius on 9/15/2009 12:29:47 PM , Rating: 3
One question:

Where did you get that 5252 number from? And what are its units?

And from an engineering perspective, I can say that you do not calculate Electric motor numbers the same way as Internal Combustion motor numbers, they are just two completely different machines. So that is why I am curious to know what the 5252 number stands for.


RE: <Drool>
By MrBlastman on 9/15/2009 12:32:43 PM , Rating: 2
I really don't know; I read the article and called my brother up to talk briefly about the car and he mentioned that number to me and I used it to reverse equate it.

Though, I just did a search and here's a neat little article explaining 5252:

http://www.revsearch.com/dynamometer/torque_vs_hor...

I didn't really question him on it, he knows his stuff so I went out on a limb with my post.


RE: <Drool>
By guacamojo on 9/15/2009 1:08:59 PM , Rating: 3
quote:
Where did you get that 5252 number from? And what are its units?


It's just a unit conversion.

Power = Torque * Angular Velocity

1 HP = 550 ft-lbf/sec
1 RPM = Pi/30 rad/sec

So Horsepower = Torque (ft-lb) * RPM * Constant

The units of the constant are HP/(ft-lb * RPM), or if you put the constant on the other side of the equation, (ft-lb)(RPM)/(HP)

The actual value is 550*30/Pi, or 5252.113 (ft-lb)(RPM)/(HP)

quote:
I can say that you do not calculate Electric motor numbers the same way as Internal Combustion motor numbers


Actually, you do. Physics = physics. But there's a flawed assumption in the OP's calculation. Peak power and peak torque do not necessarily coincide. Peak torque could be at stall, in which case RPM = zero, and horsepower = zero.

In fact, peak torque and peak horsepower rarely coincide. But that's an aside.


RE: <Drool>
By Sulphademus on 9/15/2009 2:14:46 PM , Rating: 2
quote:
Peak torque could be at stall, in which case RPM = zero, and horsepower = zero.
In fact, peak torque and peak horsepower rarely coincide. But that's an aside.


Every electric motor I have seen makes peak torque at 0rpm. I dont understand how you can have torque which, AFAIK, is motion if nothing is moving. (Well, aside from gravity) What kind of output does such a motor have when its not at 0? Like when its actually pushing the car?

5252rpm is where torque=horsepower, its the crossing point. Any rpm lower than that torque will be the greater number. Any rpm higher and HP will be the greater number. From all the dyno graphs Ive seen, this crossover tends to be at 70 to 80% torque.


RE: <Drool>
By guacamojo on 9/15/2009 4:20:49 PM , Rating: 2
quote:
Every electric motor I have seen makes peak torque at 0rpm.


Not if you've ever seen an AC motor (like on a fan, dishwasher, table saw...) AC motors have a resonant rotor, which optimizes their efficiency at speed, and reduces slippage (the difference between line frequency and synchronous motor speed.)

In an AC motor, the torque increases as you slow the rotor, up to a point called the "breakdown torque" which happens at a non-zero speed. If you reduce the speed still further, the motor torque will drop.

quote:
I dont understand how you can have torque which, AFAIK, is motion if nothing is moving.


Torque is just a rotary force. As such, no motion is required or implied. When you're standing on the cheater bar, trying to loosen the wheel nut on a VW Beetle, you're exerting a torque on the nut (equal to your weight times the length of the cheater bar), but one which isn't enough to unseat that damned nut. The nut isn't moving, but the torque is there.


RE: <Drool>
By HVAC on 9/15/2009 4:43:36 PM , Rating: 2
Electric motors that make peak torque at 0rpm are typically ones with permanent magnets inside (usually bonded or glued to the rotor). AC induction motors do not have permanent magnets, requiring oscillating electromagnetic fields to create or "induce" opposing magnetic forces in order to build up torque. Therefore, they do not have the same torque vs. speed curves.


RE: <Drool>
By Sulphademus on 9/15/2009 4:47:00 PM , Rating: 2
Yeah I've had that with lugnuts before.

Still though, torque without motion accomplishes nothing.
Example: http://www.caranddriver.com/reviews/car/09q2/2011_...
Torque (SAE net): 295 lb-ft @ 0 rpm

I know that they always publish peak numbers but if the rotary force that pushes the car forward is not rotating then its pointless as far as I am aware. The millisecond that the torque of the motor overcomes the gravity of the car, which is kinda the point, then we're no longer at 0 revs.
Maybe the torque curve is rather flat and no one's bothered to tell me?


RE: <Drool>
By guacamojo on 9/15/2009 6:32:47 PM , Rating: 2
quote:
Still though, torque without motion accomplishes nothing.


My point exactly. The peak torque of a prime mover is not the most important spec. The power output is.

Peak power, not peak torque, is what limits your 0-60 time (or more importantly, your 40-60 time.) It's what limits a car's speed, or sets how fast a truck can haul up a grade.

You can gear up or down to get more speed or torque, but no gearing in the world can give you more power than you started with.

You see it all the time in "sporty" economy cars. They have a short first gear to make the car feel peppy off the line, but they can't maintain acceleration because there's no power.

A little fractional horsepower winch can pull up a stump if you're patient and have enough gear reduction. But it won't push a golf cart up a hill at 5 mph.


RE: <Drool>
By tastyratz on 9/15/2009 1:23:33 PM , Rating: 2
curve is totally different. Electric engines aren't like a gas engine when it comes to powerband - you have to think differently.
Besides, whether it happens around 500rpm or 5000rpm, who said you cant gear appropriately?


RE: <Drool>
By Spuke on 9/15/2009 1:36:03 PM , Rating: 2
quote:
curve is totally different. Electric engines aren't like a gas engine when it comes to powerband - you have to think differently.
There's no different thinking required. The electric motors hp/torque curve is different but not so complex that it requires a change in thought process.


RE: <Drool>
By mead drinker on 9/18/2009 10:10:27 AM , Rating: 2
This is perhaps the most short sighted thing I have seen posted in this discussion. First off the car has to, by nature of design, employ some sort of dynamic stability control where each wheel's revolution is monitored so that when taking a turn the outiside wheel's rpm is great than the insides as a result of to turning radius. With out such a system the car would be wheel hopping when taking every turn, think locked differential. Now, such systems employ their "stability control" by dynamically transferring load to the wheel with traction. In such cases where anomolies are detected the system removes load and goes into a coast. I would think that the failure of an electric motor would be considered such an anomoly. Remember there are no moving parts to this "drivetrain" and load is simply removed by not providing current to the electric motor. I am pretty sure that with the current DSC systems employed today by the Fiat brand of cars, and those that fall under VW, who have designed systems that calculate some thosands of time per second that this "catostrophic" scenario would have evaded them. Simply put: If one motor fails, then the one opposite is disengaged rendering the drivetrain either RWD or FWD in a limp home mode. Wow that was complicated!


Torque
By robertisaar on 9/15/2009 10:51:57 AM , Rating: 2
"3,319.03 lb-ft"

i need new pants...




RE: Torque
By FaaR on 9/15/2009 11:15:30 AM , Rating: 3
...And don't forget that last .03 part. That's the most important bit! ;)


RE: Torque
By lco45 on 9/15/2009 11:55:38 PM , Rating: 2
You get the extra .03 on the GT model, just $23,000 extra...

Luke


typo
By Screwballl on 9/15/2009 11:29:23 AM , Rating: 2
quote:
Audio has unveiled its latest concept car...


Audio???




RE: typo
By Chudilo on 9/15/2009 11:41:32 AM , Rating: 2
Does dailytech think that Editor as a profession became useless when spell-check was invented? This could have been caught easily.


RE: typo
By ice456789 on 9/15/2009 12:15:04 PM , Rating: 3
Why pay an editor when so many are willing to do it for free?


Pot-pourri of units, affff......
By rbfowler9lfc on 9/15/2009 10:59:44 AM , Rating: 2
quote:
about 37 mph to 74 mph

quote:
promises to hit 100km/h

quote:
pack is 248 km

quote:
large beast at 3,527 pounds


Choose either Imperial or SI, would you please!!




RE: Pot-pourri of units, affff......
By chrnochime on 9/15/2009 12:57:18 PM , Rating: 2
The problem is the vast majority of ppl in the States can't understand how much a 1500kg car weighs(yes I know I wrote the weight, but tell that to an average American and you'd draw a blank stare), whereas 3300lb means something to their brains. Speed is somewhat less of a problem, for some odd reason.

There are only a handful countries left on Earth who can't be swich to the metric system for whatever reason...


By PrinceGaz on 9/15/2009 5:38:36 PM , Rating: 2
I would have thought giving the weight of a car in Kg is one of the easiest metric units to get used to. A ton is near enough 1000Kg (a metric-ton or tonne is exactly 1000Kg). Surely if you told someone a car weighed 1500Kg, they'd know what a ton and a half is?

Anyway, all countries use the metric system when it comes to science and technology, even if most of the general public in some of them don't.


Weight
By Spuke on 9/15/2009 11:49:34 AM , Rating: 5
quote:
The EV is a large beast at 3,527 pounds
The standard R8 (4.2L) weighs 3600 lbs so this car is a little lighter actually.




Sprung or unsprung?
By IcePickFreak on 9/15/2009 10:49:29 AM , Rating: 2
I admit I'm not following the electric vehicle world too closely. My question is are the motors sprung or unsprung weight? I would think they are unsprung which isn't equal to sprung weight. However I would think they would try to address this, does anyone know?




RE: Sprung or unsprung?
By randomposter on 9/15/2009 11:06:39 AM , Rating: 2
Having an 80hp (TFA quotes 313hp total) motor as unsprung weight at each corner would almost certainly be disastrous for vehicle dynamics, especially in a sportscar. I would assume driveshafts and CV joints are somehow involved.


Neat, but useless.
By 91TTZ on 9/15/2009 11:26:24 AM , Rating: 2
While it has 3,000 lbs of peak torque, it's not a very usable force. On an electric motor peak torque usually comes at 0 rpm. There is no way that it'll get any traction, so the computer is going to limit the torque output to a more usable amount. In the end, horsepower is what matters and this only has 300 hp (which isn't bad, but not awesome either).

You'd probably be better off buying a Prius and a Corvette instead of this thing.




RE: Neat, but useless.
By guacamojo on 9/15/2009 1:15:09 PM , Rating: 2
quote:
On an electric motor peak torque usually comes at 0 rpm.


That's not always true. Most AC motors have a "breakdown" torque which is greater than stall torque, but less than the peak power torque.

I believe you're correct if referring to commutated DC motors, but I believe most automotive drive motors are either AC induction or switched reluctance designs.

Could be wrong on that, though.


lol
By Murloc on 9/15/2009 2:35:52 PM , Rating: 2
Audi's American President called potential Volt buyers idiots not long ago and then quickly claimed he forgot what he said. There was only speculation surrounding the Audio EV concept at the time the comments were made.

who cares?
does this has any pertinent correlation to the article?
I mean, it's not integrated in the text.
It's like speaking of the australopithecus afarensis and then saying that bunnies jump.




RE: lol
By jbartabas on 9/15/2009 6:20:02 PM , Rating: 2
On the contrary, it is of the highest importance as it allows auto-referencing, to another Dailytech article. This is far from being the worst of its kind ...


By davidcusano on 9/15/2009 12:28:22 PM , Rating: 3
"Staggering" is a bit overstated. Adequate for a sports car is better. Remember a Corvette with approximately a 3-1 first gear ratio and a 3.4 final drive ratio multiplies the engine torque by about 10 (3 x 3.42). This means that at the wheels the Corvette is applying abut 4000 (10 x 400) ft-lbs of torque in first gear. Wheel motors have no such multiplier.




Some important data missing
By Davelo on 9/15/2009 12:56:00 PM , Rating: 3
How long does it take to recharge?
and
How much is it supposed to cost?

Since it does 0-60 in 4 secs that probably tells you how much it costs. $200k? So then *yawn*. Any company can make an expensive and fast EV. The trick is to make one that cost no more than ICE cars and gets similar performance and range.




No compromises?
By guacamojo on 9/15/2009 10:51:13 AM , Rating: 2
No compromises?

How about a 1,000 lb battery weighing down your sports car? One that provides a total range of 154 miles?

I'd say that's a hell of a compromise.

All cars are compromises. "Anyone who says different is selling something."




make a nice smoke machine maybe
By walk2k on 9/15/2009 12:33:22 PM , Rating: 1
that much tq is not terribly useful otherwise




"We can't expect users to use common sense. That would eliminate the need for all sorts of legislation, committees, oversight and lawyers." -- Christopher Jennings














botimage
Copyright 2014 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki