Supercapacitors / Ultracapacitors

I wouldn't put any stock into articles like this one as likely just grant bait.
And by the time it will be developed if it is, lithium batteries will be
even better.
Present SCs, Maxwell, cost, weigh and take up30x more than lithium.
Also it is a space charge and you just can't store enough in a
space charge.
And as someone else mentioned, it's voltage drops greatly needing to go to 0vdc to get all it's power out. Making equipment to use it very expensive along with a heavy duty BMS to keep SCs from dying from overvoltage, etc.
Nor do they live that long and seriously do degrade with just time, much less use.
SCs other than in some electronic equipment
 
Not true in real life. Well done lithium like Tesla, LG, have 20+ yr life trending, far better than any SC I know of.
 
[QUOTE="Domenick, post: 14690, member: 3"So, if I have this right, one only needs 5,000 of the D capacitors for a 200 kWh pack?[/QUOTE

That is assuming they are 100x better than present ones which is just unbelievable. Might as well believe in unicorns.
 
Domenick said:
This would be especially cool if that power could be fed straight back to the motors via inverter, instead of being put back into the battery, so it could maintain a higher efficiency.
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I suspect regenerative braking is hardly worth the effort.

The main reason is that the amount of energy to be recovered is too small. Kinetic energy is proportional to the square of the speed so at normal speed the energy available is small.

Kinetic Energy Recovery Systems (KERS) have been used in F1 cars. They are mechanical but the principle of storing energy and using it to accelerate is the same. But a racing car goes fast. Like 250 mph. The energy available is high. But if you reduce the speed to half that 125mph you have cut the available energy by 75% to only 25%. Half the speed again to 60mph, and you have only 12.5% of the energy to recover. At town speeds - say 30 mph, the available energy is down to a bit over 6%. That's why KERS is not fitted to consumer cars.

The other reason is that normal driving doesn't - if you are a good driver - normally involve hard braking which is something a F1 car does a lot of, so a KERS system would only rarely be put to use. Too rarely to justify its existence.

As a way of braking, clearly, electromagnetic braking will save wear on brake pads and is worth doing for that reason, but I doubt very much whether the energy recovered would be worth storing.
 
freedomv said:
[QUOTE="Domenick, post: 14690, member: 3"So, if I have this right, one only needs 5,000 of the D capacitors for a 200 kWh pack?[/QUOTE

That is assuming they are 100x better than present ones which is just unbelievable. Might as well believe in unicorns.
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Well, take a look at results so far:

http://www.supercapacitormaterials.com/

Working demonstrations of the material on smooth stainless steel foil electrodes are giving capacitances like 4 Farads per square cm. With etched electrodes (bigger surface area) the figure goes up to around 11 F/sq.cm. This is already 36 times what you can get from conventional supercapacitors. Of course, there's many a slip from lab to production, and there may well be some show stopper like temperature sensitivity or a propensity to go off like a bomb, but a figure of 100 times doesn't really seem to be in unicorn territory. His estimates are like 1000 times better too, not a hundred by the way, for these are the sort of improvements in measured permittivity over more conventional material he got.

The discoverer of these materials has an enviable track record in these materials too. He is the inventor of soft contact lenses and the low cost fuel cell elements being used in cars Like the Mirai and the Clarity FCV, as well as the membranes used in electrolysers. So I am more optimistic about these things than I usually am about dramatic breakthroughs. As they have teamed up with Rolls Royce to exploit them I think this gives them a degree of credence too.

But like you I will believe it when I see it!

Welcome Loaddown. The site you found is not the right one. It is a discredited scam. Until the truth came out anyway! Try the supercapacitormaterials one I mentioned above.
 
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Loaddown said:
Is this what you were looking for:
https://globenewswire.com/news-rele...ith-Relative-Permittivity-of-over-30-000.html

https://globenewswire.com/news-rele...-Releases-Latest-CMBT-Glass-Test-Results.html
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Hmmm, I wasn't aware that EEStor had been reorganized, or was still trying to promote a breakthrough supercapacitor. Well, I can't say that I'm much interested. The chances that an actual commercial product will emerge from something that started as either a delusion by the principal or a scam, or possibly some of both, are very slim and none.

I find it truly amazing that EEStor can still find investors gullible enough to give them money. Sadly, we are often reminded that P.T. Barnum was right. :(
​
 
Martin Williams said:
As a way of braking, clearly, electromagnetic braking will save wear on brake pads and is worth doing for that reason, but I doubt very much whether the energy recovered would be worth storing.
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I see that yet another of Martin's EV-bashing claims needs a reality check! :rolleyes:

Electromagnetic braking using an EV's traction motor, or "regenerative braking" as it's called, has been shown in practice to recover as much as 35% of the energy used to accelerate the car. Recovery of that much energy is certainly enough to justify the cost and engineering for regenerative braking in production EVs. That's why all or nearly all production EVs use regenerative braking.

Saving wear on the mechanical brake pads is an added bonus. :cool:
​
 
freedomv said:
And as someone else mentioned, it's voltage drops greatly needing to go to 0vdc to get all it's power out. Making equipment to use it very expensive along with a heavy duty BMS to keep SCs from dying from overvoltage, etc.
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It is true that you need to go to 0 volts to get ALL the power out, but in practice, you can get fifteen sixteenths in by accommodating a voltage range of four to one. You don't HAVE to get ALL the power out.

Switchmode power supplies capable of very wide range input voltages are easy enough to design these days. I bought a cheap chinese PSU a week or two back for a project that works perfectly from 50 volts to 240 volts - AC or DC! Its not hard to do.

The 'Heavy duty' BMS designed to prevent overvoltage is similarly easy to design. It consists of a voltage reference, and a comparator and a high current electronic bypass switch with a few resistors. Its function is to remove that capacitor from the series chain and replace it with a short circuit so the other cells continue to charge. When all have been removed the battery is fully charged and the constant current supply can be cut off. You need one for each capacitor in the chain, so if you have - say - fifty large capacitors, capable of standing 4 volts, then you need fifty protection circuits. In discharge mode they do nothing. I can't see the cost of each one being more than a couple of pounds, but if you say £5 each the total cost is only £250.
 
Martin Williams said:
It is true that you need to go to 0 volts to get ALL the power out, but in practice, you can get fifteen sixteenths in by accommodating a voltage range of four to one. You don't HAVE to get ALL the power out.
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Right. It's pointless to try to use all the energy contained in a bank of supercapacitors, because as the energy approaches zero so does the power and the voltage. If it was used to propel an EV, then at some point the voltage in the supercap pack would drop so low it couldn't provide enough power to move the car, even using a voltage converter (or whatever the proper term is).
​
 
Pushmi-Pullyu said:
I see that yet another of Martin's EV-bashing claims needs a reality check! :rolleyes:

Electromagnetic braking using an EV's traction motor, or "regenerative braking" as it's called, has been shown in practice to recover as much as 35% of the energy used to accelerate the car. Recovery of that much energy is certainly enough to justify the cost and engineering for regenerative braking in production EVs. That's why all or nearly all production EVs use regenerative braking.

Saving wear on the mechanical brake pads is an added bonus. :cool:
​
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Even if it recovered ALL 100% of the energy needed to accelerate the car, it wouldn't be worth much. The main energy expenditure is spent in maintaining speed against friction. You only recover the energy when you brake anyway, and I suspect most people simply anticipated the need to slow down and do so by easing off on the accelerator so you would recover nothing.

Were you to do a few simple sums you would find - as I did - that the kinetic energy in a two ton car doing 30 mph is only 0.05 of a kWh. Even at 60 mph its only 0.1 kWh. You have evidently swallowed the advertising hype without thought. Further evidence of your gullibility.
 
Pushmi-Pullyu said:
Right. It's pointless to try to use all the energy contained in a bank of supercapacitors, because as the energy approaches zero so does the power and the voltage. If it was used to propel an EV, then at some point the voltage in the supercap pack would drop so low it couldn't provide enough power to move the car, even using a voltage converter (or whatever the proper term is).
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ALMOST right. The voltage decreases as the energy falls, but the power - the rate at which energy can be taken - remains substantially constant. You just have to take more current as the voltage decreases. But supercapacitors can supply thousands of amps, so its not a problem.

But there is certainly no need to take ALL the power or even anywhere near the zero voltage point.

I might mention once again that these capacitors will cause a lot of charging problems. Once you provide 200kWh or more of capacity, then charging them quickly is out of the question. The capacitors may be able to take huge power levels, but the equipment needed to supply it - and that includes everything from the car back to the generator - will have to be able to provide it - and I doubt very much whether it can without a huge expenditure of cash. Even a full home charge will take 8 hours at 25kW, assuming your domestic supply will stand this level of demand. An individual house might be able to do it, but a whole road of houses all doing it would probably require re-cabling the road. Possible, of course, but who is going to pay for it?
 
Martin Williams said:
Were you to do a few simple sums you would find - as I did - that the kinetic energy in a two ton car doing 30 mph is only 0.05 of a kWh. Even at 60 mph its only 0.1 kWh. You have evidently swallowed the advertising hype without thought. Further evidence of your gullibility.
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Even for you, Martin, that's a especially silly argument. Regardless of how much or how little energy is recovered in any one instance of using regen, when expressed in kWh, it's an undeniable fact that those automotive engineers who design production EVs have found in practice that the total amount of energy recovered via "regen" is enough to justify equipping their cars to perform regenerative braking.

And the reason they do that ain't because they are "gullible"!
​
 
And the reason they do that ain't because they are "gullible"!

No its because their customers are!

I imagine if you have a battery and a motor/generator, the electronics needed to do it is pretty well cost free so why not? Particularly if the batteries are only barely adequate for even a moderate range. Particularly if the advertising can use it to pull the wool over the eyes of the public.

But you can't argue with physics. In terms of its benefit, it is negligible.
 
Martin Williams said:
ALMOST right.
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No, completely right. My statement needs no correction from someone with a rather limited grasp of engineering principles.

Martin Williams said:
The voltage decreases as the energy falls, but the power - the rate at which energy can be taken - remains substantially constant. You just have to take more current as the voltage decreases. But supercapacitors can supply thousands of amps, so its not a problem.
Click to expand...

It's a problem for the voltage converter. The greater the current, the greater the heat lost to resistance, and the more the wires and circuits are heated up, the greater the resistance... a rather unfortunate feedback effect. Practical limits will certainly cause the maximum available power to be reduced as the stored energy approaches zero.

Martin Williams said:
But there is certainly no need to take ALL the power or even anywhere near the zero voltage point.
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Clearly you are confused, since you seem to be trying to argue both sides of the question.

There would obviously be a great advantage in being able to use all the energy contained in whatever electrical energy storage system being used, whether that's an electrochemical battery pack or a supercap pack. But as I've said, practical constraints -- specifically, a lack of power at low voltage -- limit the practicality of trying to drain the last few ergs of energy from a supercap pack.

Martin Williams said:
I might mention once again that these capacitors will cause a lot of charging problems. Once you provide 200kWh or more of capacity, then charging them quickly is out of the question. The capacitors may be able to take huge power levels, but the equipment needed to supply it - and that includes everything from the car back to the generator - will have to be able to provide it - and I doubt very much whether it can without a huge expenditure of cash. Even a full home charge will take 8 hours at 25kW, assuming your domestic supply will stand this level of demand. An individual house might be able to do it, but a whole road of houses all doing it would probably require re-cabling the road. Possible, of course, but who is going to pay for it?
Click to expand...

I certainly agree that it would not be cost-effective to equip every home with the ability to charge an all-electric car at 25 kW. But nobody said that all-electric cars have to be capable of being slow-charged to 100% capacity in only 8 hours. After a long trip, would it often make a difference if the car took 2 or 3 nights to reach a full charge again? Obviously if this type of car became popular, there would be public superfast charging stations equipped to charge the cars in just a few minutes, so stopping for an en-route charge would be little if any more inconvenient than stopping at a gas station to refill a gasmobile. There would be fewer of these superfast charging stations than there are now gas stations, since most charging would be at home or at work, but it shouldn't be hard to find one in well-populated or well-traveled areas.
​
 
It's not a great problem for the dc-dc converter unless you want to get really close to zero volts. You choose the cable to be thick enough for i squared R heating to be negligible, obviously, and the 'feedback' mechanism is minor for temperatures below the melting point of copper.

Nor am I confused in arguing that there is no need to get that close to zero anyway. Only a fool would entertain such an idea. There is not an 'obvious' great advantage in taking ALL the energy for the reasons given. You'd be far better using slightly bigger capacitors and not using it all as I have - several times- pointed out here.

Regarding these 'superfast' charging stations of which you speak. I am not sure what 'superfast' means in advertising speak, but if you want to put 200kWh into the car in 10 minutes it will require power levels of 1.2MW. Good luck with that and the cost of installing it.

I think you need all the help you can get.
 
Pushmi-Pullyu said:
Well, there's another to add to our growing list of "Top quotes from Martin Williams". :p



The irony of a die-hard fuel cell fanboy claiming "you can't argue with physics"... Oy! :rolleyes:
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You could, of course, work these things out for yourself. The formula for kinetic energy is (m.v^2)/2 m being the mass of the car, v being its velocity in metres/sec and the answer is in Joules. Divide this by 3600 to get the answer in Wh and 3,600,000 to get it in kWh.

Then you could argue with yourself and avoid clogging the thread with your nonsense!
 
Martin Williams said:
Even if it recovered ALL 100% of the energy needed to accelerate the car, it wouldn't be worth much. The main energy expenditure is spent in maintaining speed against friction. You only recover the energy when you brake anyway, and I suspect most people simply anticipated the need to slow down and do so by easing off on the accelerator so you would recover nothing.

Were you to do a few simple sums you would find - as I did - that the kinetic energy in a two ton car doing 30 mph is only 0.05 of a kWh. Even at 60 mph its only 0.1 kWh. You have evidently swallowed the advertising hype without thought. Further evidence of your gullibility.
Click to expand...

You calculated the amount of energy needed to maintain speed instead of energy needed to accelerate to a certain speed.
 
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