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EEStor Issued a Patent For Its Supercapacitor
Posted by
kdawson
on Mon Dec 22, 2008 05:25 AM
from the if-it-sounds-too-good-to-be-true dept.
from the if-it-sounds-too-good-to-be-true dept.
An anonymous reader sends us to GM-volt.com, an electric vehicle enthusiast blog, for the news that last week EEStor was granted a US patent for their electric-energy storage unit, of which no one outside the company (no one who is talking, anyway) has seen so much as a working prototype. We've discussed the company on a number of occasions. The patent (PDF) is a highly information-rich document that offers remarkable insight into the device. EEStor notes "the present invention provides a unique lightweight electric-energy storage unit that has the capability to store ultrahigh amounts of energy." "The core ingredient is an aluminum coated barium titanate powder immersed in a polyethylene terephthalate plastic matrix. The EESU is composed of 31,353 of these components arranged in parallel. It is said to have a total capacitance of 30.693 F and can hold 52.220 kWh of energy. The device is said to have a weight of 281.56 pound including the box and all hardware. Unlike lithium-ion cells, the technology is said not to degrade with cycling and thus has a functionally unlimited lifetime. It is mentioned the device cannot explode when being charge or impacted and is thus safe for vehicles."
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[+]
Hardware: Charge in 5 minutes, Drive 500 miles? 319 comments
ctroutwi writes "In the wake of rising gasoline costs there have been plenty of alternatives seen on the horizon. Including Hybrids, Biofuels, fuel cells and battery powered all electric cars. CNN has recently posted a story about a company (EEStor) that plans on offering Ultra-Capacitor storage products. The claim being that you charge the ultra-capacitor in 5 minutes, with approximately 9$ (~$.45 a gallon) of electricity and then drive 500 miles."
[+]
Hardware: Lockheed Signs with EEStor to Use New Ultracapacitor 50 comments
Over a year ago, we discussed a start-up company, EEStor, that was making incredible claims about their new power source. Later, EEStor made waves with its bold predictions and secretive policies. Now, Lockheed Martin has decided to give EEStor a chance. The two companies signed a deal this week to use the new energy storage units in Lockheed's products. The folks at GM-Volt interviewed a Lockheed representative about the deal. The representative had this to say regarding EEStor:
"We've visited their facility. We were very impressed. They are taking an approach that lends itself to a very quick ramp-up in production. We've seen a lot of their testing and efforts to measure the purity of the powders that they use, and the chemistry. Well be working with them very closely this year to develop prototypes in certain pursuits."
Submission: New patent issued to EEStor on its supercapacitor by Anonymous Coward
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It must be real (Score:5, Funny)
What's the benefit of a patent for something that doesn't exist yet? At most, they're issued for things that are obvious or have existed for decades. ;)
Re:It must be real (Score:5, Funny)
Don't lose hope. Maybe there's a natural occurrence of an aluminum coated barium titanate powder immersed in a polyethylene terephthalate plastic matrix.
For all we know, that could be the composition of the droppings of a rare butterfly.
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Re:It must be real (Score:4, Funny)
Now if only you could get the fucking butterflies to do their droppings at the same spot 31,353 times in a row.
Parent
Re:It must be real (Score:5, Insightful)
To prevent it from existing unless you pay a ransom.
Parent
Re:It must be real (Score:5, Funny)
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52 kilowatt Hours? (Score:5, Interesting)
TFA:
52.220 kWh of energy
A single car battery is about 200 watt hours. The batteries in the Tesla Roadster holds 53 kWÂh according to Wikipedia.
Now thats an interesting coincidence. I wonder if they just worked out how much capacitor would be needed for the power plant of the Tesla.
Much better than a battery for cars. (Score:5, Interesting)
A capacitor has the ability for almost all braking energy to be fed back into it.
In stop-go traffic this could make a massive difference in mileage compared to a conventional battery.
Parent
Re:Much better than a battery for cars. (Score:4, Insightful)
You can do that with a good battery pack, too. The Tesla does so, in fact (as do most hybrids). The only real requirement is that the power converter be capable of running backwards, which isn't all that hard if it's a design requirement. Some extra power capacity in the batteries helps, since most cars can brake faster than they can accelerate, and you don't want to charge the batteries too fast. Fortunately, in this application the batteries are designed around capacity, and have lots of extra power capability available.
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Re:52 kilowatt Hours? (Score:5, Informative)
TFA:
52.220 kWh of energy
A single car battery is about 200 watt hours. The batteries in the Tesla Roadster holds 53 kWÂh according to Wikipedia.
Now thats an interesting coincidence. I wonder if they just worked out how much capacitor would be needed for the power plant of the Tesla.
If they can bring it to market at the stated weight (130kg) it'll makes things very interesting. The Tesla's current battery pack weighs 450kg so you could triple its range. Or cut the vehicles weight by 25% (current weight is about 1200kg).
Parent
Re:52 kilowatt Hours? (Score:5, Informative)
That is an anemic car battery you have there... Take a car battery rated 12 V, capacity 60 Ah. This battery can keep up a current of 60A for about one hour (actual capacity depends on discharge rate, lower rate equals higher capacity - up to a point). 60A * 12V DC = 720W. It can do that for about an hour -> capacity 720Wh or about 0.72 KWh. The 12V battery in my tractor has a capacity of 180 Ah which roughly translates to (12 * 180 =) 2.16 KWh. It weighs some 60kg. This EEStor maybe-real-soon-now device has a claimed weight of 128 kg. You'd get about 5 KWh worth of Lead-Acid capacity for that weight, meaning this device - if it ever sees the light of day - has about 10 times more capacity per kg.
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It's a lot better than that (Score:5, Informative)
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Re:that's *nothing* compared to a tank of petrol (Score:5, Informative)
According to the great wiki god, ic engines average 18-20% efficiency, and peak at 37%; so a tank is between 100..210 kWh usable. Presuming the 18% is around city, and the more direct applicability of regenerative braking, the difference shrinks considerably.
Parent
Fast recharge of supercaps is not hard (Score:5, Interesting)
The home recharge rate difficulties you outline don't really exist.
If mobile supercaps become affordable, then fixed home supercaps will be even cheaper, probably by a large factor because they can be much larger and heavier and less energy-dense. (You could even use lead acid batteries in the home charging station if that turns out cheaper.)
This means that your home AC supply can charge your home supercap station at whatever rate the mains wiring can stand (in particular, overnight when the electricity rates are cheaper), and then when the car comes home the home station just slams its stored power into the car's supercap at a huge rate and in a short time.
Transferring high power a very short distance is not a problem: just think very fat copper busbars and motorized conical high-area connections.
Parent
Use standard units, damnit! (Score:5, Funny)
the present invention provides a unique lightweight electric-energy storage unit that has the capability to store ultrahigh amounts of energy
Can't you express these things in units we all all understand, like jigawatts per nanofornight?
Check out the patent (Score:5, Informative)
A lot of cool data in the patent filing.
3-6 minutes charge time for 52 kWh. 286 lbs for that compared to 752 for a Li-Ion battery. And the Li-Ion takes 6h to charge.
Re:Check out the patent (Score:5, Insightful)
Better use the heavy duty extention cord.
Parent
Re:Check out the patent (Score:5, Insightful)
just imagine plugging your car in at the mall, forgetting to set a max out, and coming back to find you've downloaded 32 gigajoules, and that'll be 1000$ please sir.
A full capacitor, like a full gas tank, won't accept additional charge. Plus, you can't spill electricity, so no, you're scenario is dumb.
Parent
Re:Check out the patent (Score:5, Funny)
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Might be a good patent? (Score:5, Insightful)
Highly unlilkely (Score:5, Insightful)
--> V = sqrt((2E)/C)
--> 3500 = sqrt((2*187992000)/52.22)
3500v is a lot. Up until now most comercially available supercapacitors do 5.5v or less and tend to leak energy over time. It's possilbe these guys have really made a stunning break through (the fact they filed for a patent is sure something), but the numbers set off my bullshit detector.
I think the BS is even higher. (Score:5, Interesting)
The EESTOR stuff has been analyzed---yes buy some random guy on a blog, but somebody who really seems to know what he's talking about.
Only in freshman physics can you say that the energy in a capacitor is simply E=1/2 C*V^2---or more correctly---measure the capacitance at V=approx 0 and then extrapolate.
Barium titanate is definitely a known ferroelectric (this is not misspelled) material with a very high dielectric "constant" k.
But it it is not really constant! At sufficiently high voltages (i.e. interesting for power storage) you get dielectric saturation, meaning that k = k(V) in reality and it declines heavily. You just can't make atoms and electrons do what EEstor wants. There isn't enough place to stably put that much energy in electrons unless you change their energy states--which is otherwise known as chemistry---and gasoline.
And if you have 50 kW-hr or so in a little place, and you get a short thanks to a collision which breaks the circuits, there's no way to NOT have a freaking BIG ASS meltdown and explosion. That potential energy IS going to go somewhere and if it was all in E-fields and capacitance, it will discharge really fast if there is a hint of a dielectric breakdown and this will vaporize.
Only if the 50 kW-hr is experimentally measured, not imputed from a low power separate measurement of capacitance or dielectric constant, will I believe it.
I have the feeling that this patent document may really be used for continuing the funding cycle, not actually protecting a (nearly physically unbelievable) technology.
They probably did create a very good ultracapacitor with good materials processing, but I bet the energy storage is still in the ballpark range of known ultracaps.
Having it be otherwise would be like saying you've refined petroleum into a new chemical fuel which has the energy density of fissile uranium, and no radiation!
There isn't any Moore's law in thermodynamics.
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Interesting specifications (Score:5, Informative)
No one has noted yet that these caps also have insane *individual* unit specs! They're rated for 3500 V, have about 1 milli Farad and weight about *5 grams* each. This is absolutely unheard of. Normally you have to choose two from: small size, high voltage and high capacitance.
The energy that a cap contains is written as E = U^2*C, so it's obvious that scaling up the voltage gives you high rewards very rapidly. The problem has been that the insulating layers inside caps cannot handle high voltages without being made very thick. This means less capacitance since ideally the plates should be as large as possible and as close as possible.
The bill of materials looks nice too: Aluminum, Barium, Titanium, simple plastic. If they can actually produce the goods, this could be very cheap to mass produce.
If they can commercialise this, it *will* revolutionarise portable power (3500 V inside your iPod?;). But until they show a working prototype I'd hold my horses and not bet on this to solve our energy storage problems.
Oh, this is clever. (Score:5, Interesting)
At first I wasn't getting why this would have better capacitance than conventional materials. Then around page 6, I realized that they're laying down a lot of layers. Like, a micron of conductor and nine microns of dielectric in each pass.
This is what patents are really for.
-jcr
Re:Oh, this is clever. (Score:5, Interesting)
Well, the material is basically a laminate where a majority of the volume is teflon, and the conductors are sintered metal powders. I haven't heard of teflon getting brittle at low temperatures, and I wouldn't expect the conductors to be prone to breaking, either.
I think that you'd probably have to worry about the copper in the motor windings of an electric car shattering at low temperatures before you'd have to worry about the capacitors.
-jcr
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Instant stats (Score:4, Informative)
The stats are awesome for this if it's true. Here's a quick lowdown. Full stats are below (taken from PDF doc).
The weight is more than twice as light as Lithium Ion
The volume is 20% smaller than Lithium Ion
The charging time is 60x faster than Li-ion (15x faster than NiMH)
-----, EESU, NiMH, LA (Gel), Ni-Z, Li-Ion
Weight (pounds), 286.56, 1716, 3646, 1920, 752
Volume (inch^3), 4541, 17881, 43045, 34780, 5697
Discharge rate/30 days, 0.1%, 5%, 1%, 1%, 1%
Charging time, 3-6 min, 1.5h, 8h, 1.5h, 6h
Life reduced with deep cycle use, none, moderate, high, moderate, high
Hazardous materials, none, yes, yes, yes, yes
May not explode, but.... (Score:4, Insightful)
It is mentioned the device cannot explode when being charge or impacted and is thus safe for vehicles.
It may not explode when you hit it, and I'm not genius with electricity, but can't capacitors discharge their energy pretty quickly? Wouldn't 52kWh discharged through a pile of metal with people trapped inside be somewhat less than safe?
That's an incredibly good dielectric plastic (Score:5, Interesting)
Back to basics. A capacitor is an insulator between two conductors. The key concept here is that their insulator has an insanely high breakdown voltage, which is why they can supposedly make an ultracapacitor that operates around 500V instead of the usual 5V or so.
The patent says "The alumina-coated calcined CMBT powder and the poly(ethylene terephthalate) plastic have exceptional high-voltage breakdown and when used as a composite with the plastic as the matrix the average voltage breakdown was 5.57 * 10^6 V/cm or higher. The voltage breakdown of the poly(ethylene terephthalate) plastic is 580 V/micrometer at 23 degrees C. and the voltage breakdown of the alumina-coated CMBT powders is 610 V/micrometer at 85 degrees C."
Note how many different units they use. Conventionally, dielectric strength is quoted as KV/mm. So we have
First, why did they make a composite that's worse than either of its components? This would be obvious if they used the same units for all their breakdown voltages in the patent.
Second, those are unreasonably good numbers. The usual breakdown voltage for PET [azom.com] as used in Mylar capacitors is only 17 KV/mm. Why is their PET 35 times as good as everybody else's?
(Check this, please. Look at the actual patent image. [pat2pdf.org] The searchable text version at the USPTO doesn't show math symbols very well.)
Re: can hold 52.220 kWh (Score:5, Insightful)
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Re: can hold 52.220 kWh (Score:5, Informative)
How do you figure?
The patent specifically mentions kW*H in reference to the 52.220 number.
I assume you were just trying to be smart and correct the summary thinking it was a typo. However, a kW*H is a valid unit of measurement.
In fact you could use them interchangably but it would give the very wrong idea as they measure different things.
A watt is one joule of energy flow over a second. so a KW would be 1000 joules of energy flow over 1 second.
A KW*H is a flow of a kilowatt continuously over an hour, therefore it would be a flow of 1000 joules over 3600 seconds.
So to recap:
1 kw = 1000 joules/sec
1 kw*h = 1000 joules/sec * 3600 seconds
If you were just going to measure the total energy usage, you'd have to keep it just in joules, in which case 52.220 KWH would be 187,992,000.
So yeah, big difference caused by little changes in notation. Of course i haven't done electricity in ages so i probably oversimplified somewhere and fubar'd up.
Parent
Re: can hold 52.220 kWh (Score:5, Informative)
It's NOT KW*H! It isn't kw either, nor is it kw*h.
It is however kWh, meaning kilowatt hour, and it is a unit of energy.
Start getting you units right, and capitalization DOES matter. M = mega, m = milli.
Parent
Re: can hold 52.220 kWh (Score:5, Insightful)
I think, in the context of a slashdot forum, anything is okay so long as a reasonable person can discern meaning. mW vs MW is indeed a problem, but kw vs kW??? What exactly did YOU think the 'w' stood for?
Never, in any context is it ok to write incorrect information. And the problem comes when people start writing mw, Mw, mW and MW respectively, and then mixing 1,000 with 1.000. The numbers get way way way off, so it is _never ever_ ok to start messing with units and hoping the reader "gets what you mean" just because you are lazy.
And people correcting other people, they just have to get things correct or it's an epic fail. What is the point if being a smart ass, if you are just another dumb ass who gets it wrong again?
The correct figure is: 52.22 kWh
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Re: can hold 52.220 kWh (Score:4, Informative)
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Re:But How To Charge It? (Score:4, Informative)
Approximately 3000 amps. 460 volt/ 3 phase: about 830 amps.
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Re: can hold 52.220 kWh (Score:4, Funny)
k, not kw.
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Re:No, it's killowatt-hours. (Score:5, Informative)
Actually the watt-hour is a measure of (electrical, in this case) energy. It's an awkward convention, but it makes sense when you realize that Watts are equal to Joules over time and that multiplying time back in leaves you with Joules.
It's not so awkward if you consider typical domestic usages: since most appliances have power consumption in the order of watts and kilowatts, and typical usages are in the hour (not second) timescale, it's much more comfortable to use: after all, 1 J = 1 W*s, so you'd need 3.6 MJ to describe the energy consumed by a 1 kW boiler functioning for 1 hour ... much more comfortable to just say it's 1 kWh
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Re:No, it's killowatt-hours. (Score:5, Interesting)
My average power consumption is about 30 kWh per day. This varies dramatically from summer to winter, with winter loads being much higher due to an electrically heated kitchen floor, a low-efficiency fan motor on the gas furnace, and heavier use of lighting (although this appears to be a minor consideration).
One of these units would fit nicely into my utility room, and give me about 1/2 a day of power in the winter and several days during the summer. Power reliability in Toronto is excellent in any case, but this would eliminate every blackout Toronto has seen, including 2003.
Maury
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Re:Cannot explode but can be used in cars? (Score:4, Informative)
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Re:Cannot explode but can be used in Fords? (Score:5, Informative)
IIRC, Pintos didn't actually "explode" (except in the movie "Top Secret"). Instead, they poured the entire contents of their tank onto the ground in the case of a rear collision. The big gasoline puddle could then catch fire.
There's a video here [youtube.com]. Lots of flames, no flying shrapnel :)
Parent
Re:Cannot explode but can be used in cars? (Score:5, Interesting)
Now its good that this thing allegedly won't explode while being charged
Welcome to the wonderful world of internal resistance.
Wikipedia files it under output impedance, although no one outside of maybe textbooks refers to it that way.
http://en.wikipedia.org/wiki/Internal_resistance [wikipedia.org]
In summary, no perfect current or voltage sources exist. All power supplies can be modeled as a "perfect" supply with a series resistance.
In practice the difference can be huge. Short out an old fashioned 10 aH zinc copper gravity cell and nothing particularly interesting occurs due to its high internal resistance. Short out a 10 aH nicad, and good luck dodging the shrapnel.
Another amusing comparison, when NiMH batteries were very new, like in the late 80s, RC car racers like myself were impressed that they held around twice the charge of the old NiCd technology. However, the internal resistance was so high, that they didn't go so fast. I guess in the intervening decades NiMH now has a low enough resistance to use in RC cars, but that sure wasn't always the case.
Internal resistance has always been the problem for supercapacitors. I remember being quite disappointed when, as a kid a few decades ago, I bought one of those newfangled carbon based super caps, like 0.1 farad at 5.5 volts, and expected if a couple thousand uF made a shower of sparks when shorted out, 0.1 farad should make like an atomic explosion when shorted, however the internal resistance of the cap was like multiple ohms so it didn't even spark. I vaguely remember that once charged it ran a LED a long time though.
The problems super caps always had (until now?) is you need a ultra high conductivity for the plates to get a low internal resistance and a ultra low conductivity for the dielectric (not dialectic, that's another story) to get low leakage currents, and both have to be compatible with each other (from an electrical standpoint, sodium metal foil and ultra purified water sounds like a good capacitor design, but from a chemical standpoint, maybe not so good. Chlorine is probably an even better insulator than water in this application). Finally it would be nice if it were made without toxic waste like PCBs or beryllium oxide insulators (both of which have been used in electronics applications in the past). And then there's minor little things like mechanical stability, manufacturing problems, and material sources like tantalum. Their claim to have worked around all those problems is what makes this patent very impressive, if true.
Parent
Re:Cannot explode but can be used in cars? (Score:5, Informative)
If we really want to split hairs, we should note that "explode" and "detonate" are two different concepts. Some explosions are detonations, and others are simple deflagration where the fuel burns rapidly but evenly over some period of time.
The physics of the two is vastly different. A detonation denotes an event where the material burns at a rate that is supersonic, and a deflagration is subsonic.
In a detonation, an instantaneous pressure jump moves through the material faster than the material's normal speed of sound. This produces instantaneous pressures that can go into the millions of PSI. A strong enough shock will shatter any material.
Occasionally, the fuel/air mixture in an automobile cylinder will partially detonate. These cause weak shocks that we notice as "knocks" and "pings" - and which over time will destroy the pistons in the engine. High compression, low octane fuel, and local hotspots in the cylinders are the usual reason for this.
As a side note, even smokeless gunpowder doesn't detonate, it just deflagrates on a time scale of 0.5 - 3 milliseconds. If it did detonate, the gun would quite spectacularly imitate a fragmentation grenade.
From the perspective of an observer outside the combustion both can produce similar effects, though detonations are much more spectacular.
Parent
Re:Cannot explode but can be used in cars? (Score:5, Informative)
A combustion event, aka 'explosion' occurs at the beginning of every power stroke in a reciprocating internal combustion engine. When an engine 'knocks' there is a combustion event as well. What makes it a 'knock' instead of a normal part of the power cycle is that it occurs at the wrong time. Knocking indicates perhaps a spark timing issue or the use of a fuel with an improper octane rating (which indicates resistance to knock). Octane ratings describe the resistance of the fuel to spontaneous ignition relative to a mixture of iso-octane (by definition Octane rating of 100) and n-heptane (by definition an octane rating of 0). Extrapolation is what allows for an octane rating of greater than 100. Diesel fuel has a similar concept, a Cetane number which indicates susceptibility to "spontaneous" combustion, since diesels use compression to ignite combustion events rather than an electrical spark.
Modern cars do depend on a much higher octane rating than historical vehicles. This allows for running on a much higher compression ratio and/or the use of turbo-chargers which allow for an engine that is thermodynamically more efficient (as compression ratio approaches infinity, thermodynamic efficiency approaches unity). This is one reason why diesels (compression ratios in the 20's rather than 5-10 for gasoline vehicles) get better mileage for a comparable vehicle/power output.
You are, however, entirely correct about the relative difficulty of causing a gasoline burn or explode. Only the vapor state is flammable and only at a narrow range of particle size.
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Re:Cannot explode but can be used in cars? (Score:5, Interesting)
Modern cars do depend on a much higher octane rating than historical vehicles.
It's actually the opposite - Our cars are normally built to run on pretty low octane ratings today. We have to take a huge swath of the stack for gasoline to satisfy our demand for it, and the result is that our gas, knock wise, is pretty low.
From what I can find, the Model T ran on 93 octane. Not exactly what I'd call a low octane.
Early gas was actually pretty high octane(but tolerances weren't as tight); we didn't actually need all that much of it and it was still competing against Ethanol*, among other fuels. It was only later that gasoline demand started getting high enough that they started running short on the higher octanes, and needed to mix in lesser octane hydrocarbons.
One interesting fact i came across was that the Model T was Ford's original dual fuel vehicle - it featured manual spark advance control and could run on anything from 100% gasoline to 100% ethanol.
*During this time period, everything was competing. There were dozens of electric car companies; steam, ethanol, diesel, gasoline were all competing.
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Re:Cannot explode but can be used in cars? (Score:5, Informative)
A combustion event, aka 'explosion' occurs at the beginning of every power stroke in a reciprocating internal combustion engine. When an engine 'knocks' there is a combustion event as well. What makes it a 'knock' instead of a normal part of the power cycle is that it occurs at the wrong time
This is incorrect. When things are functioning normally, the fuel burns by deflagration, the reaction front is propagated subsonically by conductive heating of adjacent material. If you have knocking, what's going on is detonation, where the reaction front is propagated supersonically by compressive heating of adjacent material. Both deflagration and detonation are combustion reactions, but the latter is more powerful, less efficient, and far more destructive to your pistons. It's not just the same reaction occurring too early.
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Re:Wow, cool (Score:5, Insightful)
From the numbers in the summary, a fully-charged one of these would supply enough energy to propel a 3300lbs (1500kg) car from 0 to 1100mph (500m/s)
Ahhh you must be from the Theoretical Physics Department, over here in Engineering we have wind resistance, friction and efficiency to worry about.
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Re:Wow, cool (Score:4, Funny)
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Re:Wow, cool (Score:5, Funny)
Ahhh you must be from the Theoretical Physics Department, over here in Engineering we have wind resistance, friction and efficiency to worry about.
--
Ahh you're from the Engineering department... Over here in the Manufacturing department we have to worry about cost ,liability ,feasibility ,and marketability to worry about.
and don't you dare talk to marketing, both of you will confuse them and those idiots will go out telling everyone we can go 10,000 miles and charge in 6 seconds for -$10.00.. "Why you'll make money!" they will market this very wrong.
So when marketing comes by, look sad and say it kills puppies.
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Re:Wow, cool (Score:5, Funny)
I'm from the Legal Department, and I just got off the phone with $ANIMAL_RIGHTS_GROUP.
Apparently someone has been telling marketing that we kill puppies for fun, and they spun it as a feature.
Anyone want to explain to the R&D Department why their funding is getting cut?
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Re:Comparison with gasoline (Score:5, Informative)
In their favour, an electric motor is much more energy efficient than an internal combustion engine. 20% seems to be the maximum for a practical internal combustion engine. Electric motors should easily be able to reach 90% efficiency, with the record being 98% efficiency [csiro.au]. Thus that 4.5 litres of petrol (1.2 US gallons of gas) becomes 20 litres. Not too bad for a first attempt, given that a small car (eg. Toyoto Echo/Yaris) typically takes 30-35 litres of petrol on a fill.
Yaris and their ilk aren't the model of efficiency in their design. Surely it wouldn't be too hard to make a Yaris type car use 35% less energy, resulting in a capacitor powered electric car with similar range to a petrol equivalent?
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Re:Only a couple of days? (Score:5, Interesting)
The range would depend mostly on how fast you're going. The relationship between power use and speed is (generally) cubic, due to the equation for energy loss to drag.
IIRC, when I was running numbers in a previous discussion here about the smart fourtwo car, I came up with something like 37.5HP (~28KW) needed to maintain 80MPH (Highest speed limit in the US, AFAIK). That would give you a bit less than 160 miles on that thing. Slow that down some and the range significantly increases though.
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Re:Bass (Score:5, Funny)
Yes, briefly.
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