Charge Your Cellphone In 20 Seconds (Eventually) 295
New submitter GoJays writes "An 18-year-old from Saratoga, California has won an international science fair for creating an energy storage device that can be fully juiced in 20 to 30 seconds. The fast-charging device is a so-called supercapacitor, a gizmo that can pack a lot of energy into a tiny space, charges quickly and holds its charge for a long time. What's more, it can last for 10,000 charge-recharge cycles, compared with 1,000 cycles for conventional rechargeable batteries, according to the inventor Eesha Khare." This one in particular has been used so far only to power an LED, rather than a phone or laptop, but I hope in a few years near-instant charging of portable electronics will be the norm as supercapacitors grow more common.
supercapacitors are cool (Score:5, Insightful)
Re:supercapacitors are cool (Score:5, Insightful)
Another problem is which wire you need to move all that energy into the capacitor in that little time. This applies both to the wire from the wall to the device and the one from the grid to the house (where I live residential contracts are usually limited to 3 kW). I didn't do the math but assuming it's not a problem for a cellphone it might be a problem for a charging a car fast. In a reverse-car analogy it's like having a 2 Mbit DSL to the Internet. Downloading a movie is going to take a long time a Gigabit home network won't help.
Re:supercapacitors are cool (Score:4, Interesting)
In a reverse-car analogy it's like having a 2 Mbit DSL to the Internet. Downloading a movie is going to take a long time a Gigabit home network won't help.
We have overland lines a few hundred yards from our house, and there is a gas pipeline running right under the stables. It should be easy to recharge either an electric car or a natural gas powered one in the course of milliseconds.
The problem are the taps. As a result, our AC is quite less dependable than the buzz of the overland lines, and we don't even have gas in the house, instead having to make do with (quite more expensive) oil heating.
Maybe we should go for inductive car charging and park the car under the overland lines.
Re:supercapacitors are cool (Score:5, Interesting)
To extend the reverse-car analogy, the correct analogy is the use case of wanting to transmit a large movie to a USB stick so you can watch it on your TV. Doesn't matter if you have the best-of-the-best USB stick and USB 3.0 in your computer. The bottleneck is still the internet connection. So what you do is that you set your computer to download that large file while you're out doing whatever it is you're doing all day, and copy it over to your USB stick quickly when you get home. (You could even conceivably automate this process or remote control it from your cell phone.) In this scenario, having USB 3.0 *will* help since it'll cut down on the time on getting the movie from your computer to the USB stick.
Analogously, the way you'd do it for a residential charger, is that you'd have the power grid trickle charging a supercapacitor that you have at your home (ideally under some kind of control from the power company, so that they can manage the load on the electric grid) over the course of a few hours, so that when you need the power, you can just plug it in and almost instantly get your car charged up.
Although while we're on the subject of analogies, a better reverse-car analogy would be that of a flush toilet, slowly building up a reservoir of water to then quickly release it when required.
Re:supercapacitors are cool (Score:5, Funny)
I think a better toilet-related analogy for slow intake and fast discharge would be someone at an all-you-can-eat taco buffet.
Re: (Score:2)
I think a better toilet-related analogy for slow intake and fast discharge would be someone at an all-you-can-eat taco buffet.
That's nothing. Think of a kid at a U-Pick-Em tomato farm, where they eat more than they put in the basket. I can say from personal experience that those are great places to take kids, but do watch their intake.
Re: supercapacitors are cool (Score:5, Insightful)
Re: supercapacitors are cool (Score:5, Informative)
http://www.usc.edu/CSSF//History/2013/Projects/S0912.pdf [usc.edu]
Not so novel: "Incorporating the utilization of carbon nanotubes cathode and TiO2 nanotubes anode in energy storage, a nonaqueous hybrid supercapacitor was developed in order to significantly increase the energy density of the supercapacitor."
http://www.ncbi.nlm.nih.gov/m/pubmed/18019169/ [nih.gov]
Also dr yat li which she claims was "supervising" her seems to think he invented it a year ago without her help. Notice his name is on this article with other doctors but her name is missing: "Hydrogenated TiO2 Nanotube Arrays for Supercapacitors"
http://pubs.acs.org/doi/abs/10.1021/nl300173j [acs.org]
She basically did a chemistry experiment that had already been done and published, she invented nothing
Re: (Score:3)
yeah, but it's so much cooler to say she invented it than to say she had a connection to get into a lab and copy what someone else had done. It's not liek the other experiments are filled with novel, unique ground breaking research. Most of this stuff is just rehashed work of some researcher who let them sit in the lab and do the same things they had done.
I have calibrated and help set up a laser trap for some biophysics research. doesn't mean I invented the laser trap. But they are always going to talk
Re: (Score:3)
Flash is very slow at writes. An SD card "class 4" or "class 6" means it's rated for writing at at least 4MB/s and 6MB/s respectively. If your USB flash drive can do much more than that then it's very recent or high grade or both.
I've also had a wifi network where I would reach 1MB/s when copying stuff yet the Internet connection could do 1.5MB/s on download.
Re: (Score:2)
Dude, the circuit for my home office (originally meant as spare bedroom) is rated 3kW, and in the winter I have to be careful to run the electric heater I keep under my desk at 750 rather than 1250W lest I trip the breaker and thus kill the router.
Maybe you meant 30kW?
Re: (Score:2)
Re:supercapacitors are cool (Score:5, Informative)
Um, you and everyone commenting has missed a major detail. Don't you geekheads know about circuit breakers? Your room is probably wired to a 20 or 25 amp circuit. Check the breaker and replace it with a larger one, say a 30 and you will probably be able to run everything at once without a fire.
I think you're just trolling, but if anyone is reading this and thinks just swapping out the breaker or fuse is a good idea, remember that it's the size of the wire that determines the safe current limit of the circuit, not the size of the breaker. In the USA,NEC specifies: 14 gauge wire = 15 amp, 12 gauge wire = 20 amp, 10 gauge wire = 30 amp. (but these are maximum values that may need to be derated in some conditions, like multiple conductors in conduit, especially long circuit runs, etc)
Re: (Score:2, Funny)
Re:supercapacitors are cool (Score:5, Insightful)
The fuse would blow regardless of the power supply....
You short a battery and it generally explodes as well. The advantage here is with the quick charge time you could get away with storing less energy in your phone.
Re: (Score:2, Informative)
Drop a spanner on the poles of a truck battery, and the battery does not exactly explode (the poles may get damaged). But molten metal flying around is still not fun. The problem is not the capacitor, the problem is whatever may do the shortcircuiting.
Re: (Score:3, Informative)
Sigh! Supercapacitors are inherently stable and generally won't explode unless you actively force them too (i.e. most things explode when you put 1kV up it's arse).
High energy densities and high currents are emitted when shorted and you end up with maybe a spark. Quite a safe spark though given the pathetically small voltages they can store. The same can be said for non-super capacitors too. The only only ones which really let go with a bang are tantalum caps, and even they are quite stable run under their
Re:supercapacitors are cool (Score:4, Interesting)
Even smarter, not one super capacitor but a whole series of them, which discharge into a low capacity rechargeable battery (that high output discharge will actually extend the life of the battery as it would prevent crystalline build up), in sequence to provide smooth delivery of power. The series of small super capacitors can still be charged at high speed and via a more regular rechargeable battery provide smooth delivery of current.
Re:supercapacitors are cool (Score:4, Informative)
Even smarter, not one super capacitor but a whole series of them, which discharge into a low capacity rechargeable battery
Let's take a look at why that is not smarter. You are throwing away the energy density and quick charge properties, and increasing complexity by adding, most likely, another entire charge controller. As well, there is absolutely no need to use an array of supercapacitors, because supercapacitors are the solution to the problem of needing an array! They have fast charge and discharge, they already act wide and not just deep.
You're throwing away energy density by wasting space on having two power systems, and you're throwing away quick charge by including a power system without quick charge. You'll want a separate charge controller for the separate power system, and that means still more efficiency loss and still more cost. It just doesn't make sense.
Re: (Score:3)
Voltage is irrelevant. If a short releases the stored energy, all of it is converted into heat, since it has nowhere else to go. If stored energy is significant, and is released in a short enough time, this results in an explosion.
So, the safety-relevant questions are: how much energy can a capacitor store, and how much currency c
Re:supercapacitors are cool (Score:5, Funny)
and how much currency can it supply?
Are you suggesting any company that brings a viable solution to market is basically going to be printing money?
Re: (Score:2)
Re: (Score:2)
- Said someone who never saw a fuse in his life, and never got a piece of wire glowing by shorting a Ni-Cd cell.
IOW: So how is it different from the batteries we have now, as far as your pseudo-concerns are concerned?!
Re: (Score:2)
Batteries are unable to discharge at speed anywhere near that of supercapacitors. That's what one of the main advantages of capacitors over batteries - charge and discharge speeds. Car analogy: you're arguing that crashing a supercar going at full speed is comparable to crashing a typical sedan stuck in the first gear.
Re: (Score:3)
If they are to be useful, they need to store substantial amounts of energy. A Samsung SIV has a 2600 mAh at 3.7V -- anything that's substantially less for the same size ain't gonna cut it, because even with fast charging, you aren't gonna want to charge ten times a day.
10 Watt-hours isn't a HUGE energy-amount, but it's not trivial either. Charging in 20 seconds means supplying the device with about 2 kilowatts of power. A catastrophic short-circuit discharge that drains the supercap in a second while meltin
Re: (Score:3)
I don't know where you got your numbers from, but the energy density [usc.edu] this supercap has is on par with batteries: 20Wh/kg. Now look at the size of the caps she has [nbcnews.com]. Those are samples that weigh grams. Whatever fits in a cellphone will weigh probably on the order of 100g, and will store on the order of 1 Wh. I don't see kilowatts for charging, never mind that you absolutely don't have to charge in 20s. A one minute charge cuts the power by a factor of 5, and anyone sane will go with what's economical and make
Re:supercapacitors are cool (Score:4, Insightful)
the energy density [usc.edu] this supercap has is on par with batteries: 20Wh/kg
The grandparent quotes a battery capacity of 10 Wh. That's not remotely a 500 grams stuck into a corner of a cellphone. For comparison, my cellphone battery is 1650 mAh and 33 grams. That's 185 Wh/kg. I wouldn't call 185 and 20 "on par."
Re: (Score:3)
even with fast charging, you aren't gonna want to charge ten times a day
Maybe.
Fast charging + wireless charging + ubiquitous charging stations might make it very practical. For my lifestyle a two-hour battery life with 20-second recharges from just putting my phone on a certain region of my desk, nightstand, car console, etc. would work just fine.
Re: (Score:2)
Regular cell phone batteries have a charge of about 2Ah, assuming this super-capacitor will have a similar charge and remembering that a capacitor can be discharged at least as fast as it can be charged, in 20 seconds or less, this could create an average current of 360 ampere, give or take a few ampere. Given the nature of the current flow when discharging a capacitor the current will b
Re: (Score:3)
I had some very large electroltytic caps in an variable out DC power supply I designed get switched around during a pilot build and make it through final inspection, and when I powered the first 8 of them up and those 10V caps saw 48V on our endurance stand the whole room was lit up like the 4th of July as molten aluminum and shrapnel blasted me in the face, it was quite exciting.
Cheers
little light on the science details. (Score:3)
did she have some new angle to the tech?
you can buy capacitor based battery replacements for cars.
Re:little light on the science details. (Score:5, Insightful)
did she have some new angle to the tech?
you can buy capacitor based battery replacements for cars.
The only new thing in there was "holds its charge for a long time", which I thought was the only real barrier to supercapacitors replacing batteries. I suspect that "a long time" isn't quite correct for useful values of "long".
Safety is obviously a concern too, but industry doesn't really need to worry about that until the first cell phone blows someone's ear off or laptop blows someone's crotch apart.
Re:little light on the science details. (Score:5, Informative)
Yes. The article was terrible. She almost tripled the energy density of supercapacitors. From her paper [usc.edu]:
Re: (Score:3)
Mod parent up. What I want to know is where did she get access to technology that could operate on the "nanoscale" as well as fabrication equipment, this stuff isn't exactly commonplace or cheap. Although it would be great if it was in every school.
Re: (Score:3)
http://www.youtube.com/watch?v=RVUf7-tTLXo [youtube.com]
Re: (Score:2)
What I want to know is where did she get access to technology that could operate on the "nanoscale" as well as fabrication equipment, this stuff isn't exactly commonplace or cheap. Although it would be great if it was in every school.
High school students working at this level often (and fortunately) get access to university labs. Typically via a faculty "sponsor" for someone who is very promising.
Re:little light on the science details. (Score:5, Informative)
Mass energy density of commercial supercaps is 3-5 Wh/kg, but 85 has been seen in the lab, according to Wikipedia. Her's is 20.1, which may be significant if it can be commercialized.
Some more numbers (Score:5, Informative)
Interesting numbers. Just to compare, here's the energy densities of lithium-polymer batteries and super-capacitors, taking the values for best easily-available components I could find.
LiPo: 168 W.h/kg, 370 W.h/l
Super-cap: 5.1 W.h/kg, 6.6 W.h/l (I'm being slightly generous to the capacitor here, by counting the energy to discharge it to zero volts. In practice that last bit of energy will not be usable.)
The volumetric figures are most critical for phones, and in those terms batteries are 56x better than super-capacitors. So an improvement of 3x is interesting, but there's a lot more work to do.
Discharge rates (Score:5, Informative)
Re:little light on the science details. (Score:4, Interesting)
Hmm, I don't understand these numbers. 20 Wh/kg works out to 72 kJ/kg, which is much less than the 1.08 MJ/kg Wikipedia quotes for supercapacitors. On the other hand the article on supercapacitors claims 15 Wh/kg to 30 Wh/kg as the typical range of commercially available values, so perhaps the other number unrepresentative. Anyway, these numbers would place the 20 Wh/kg result in the article squarely inside the range of commercially available supercapacitors when it comes to energy density. This is also about 10 times lower energy density than rechargable lithium batteries. So not exactly something you want in your mobile phone.
Re: (Score:2)
No, that's what happens when you do it at a university lab, not at home while being clueless to boot. That's all.
Re:little light on the science details. (Score:5, Funny)
did she have some new angle to the tech?
Yes, she did. She used a "led" as a demo device for her super battery.
Basically, a led is the equivalent a cell phone without a screen, without an antenna, without sensors, without memory (except for one bit), without a gps, without a speaker, without a microphone, without an amplifier, without a cpu, without a gpu, etc. Plus, it's a great device for simulating the power consumption of an actual cell phone.
A "led" is a also a great device to give your kids instead of a cell phone. It doesn't have a great range, may be just a couple of meters. And it needs to be in the constant line of sight of the person your kid is communicating with. But barring those two little constraints, it's a good tool for your kid to learn morse code (provided that "led" is the only piece of electronics/toy your kid has access to), it works great at night, it comes with uncapped/unlimited data, and it doesn't come with an expensive bill no matter how much your kids do texting with it.
Re:little light on the science details. (Score:5, Funny)
The problem is that Ubuntu touch doesn't support the 1x1 screen resolution. We need the inventor to release the specs so a Mir graphics driver can be written. I've tried an alpha version and personally find the scroll bars tricky, but then that's always been a problem with Unity. This is the problem with Canonical trying to get one OS to work every device.
Phillip.
Re: (Score:2)
You could get one of those gamers backlight keyboards - they have a single RGB color value that can be programmed so all the keys can be any one of 16 million colors. Some even have an itty-bitty 320x240 LCD screen that can be accessed via USB.
Re: (Score:2)
ubuntu is my god. (Score:2)
how dare you. HOW DARE
Re: (Score:2)
At 5-10 mA, the power draw of LED is comparable to that of an idle phone, that powers only the receive circuitry.
Which is ideal if you're trying to demonstrate that the self-leakage of the capacitor is not a serious impediment, since the self-leakage is a greater issue when the cell phone's power consumption is less.
Gizmo? (Score:4, Insightful)
Sometimes I really hate "technology" reporting.
Re:Gizmo? (Score:5, Insightful)
Quite.
Supercapacitors have been around for a couple of decades, getting a lot cheaper recently.
Tens, or hundreds of millions of dollars have been spent on their development.
At the moment, they lag _considerably_ behind cellphone batteries in terms of energy storage per unit volume, and cost.
Sure, you can make a supercapacitor battery for your phone and it will charge in 10s. But it may only run the phone for several minutes.
The above article gives absolutely no information whatsoever that indicates the student in question has overcome this barrier, which is absolutely key.
Otherwise, this is just a 'student invents flying car' - when the proof given is a balloon tied to a toy car.
A very cynical person might say that the reason for the award was in the photo.
I am not saying that the student has not done work beyond simply sticking a $7 capacitor in a box with an LED, but that is all the article can lead one to guess.
Re: (Score:3)
On closer reading, I find that it does indicate she fabricated the capacitor - which is noteworthy, and an achievement for someone of her age - but unless she has achieved actual breakthroughs in the field, this is again not nearly as newsworthy as the headline suggests.
Re:Gizmo? (Score:5, Informative)
but unless she has achieved actual breakthroughs in the field, this is again not nearly as newsworthy as the headline suggests.
She has. [usc.edu] The only problem here is that the news itself is dumbed down to the point of being utterly pointless.
Science reporting at it's finest.
when i was 18 my main accomplishment (Score:2)
was ruining about 20 pairs of bedsheets with cum stains, and finishing X-Wing vs Tie Fighter
Re:Gizmo? (Score:4, Informative)
A very cynical person might say that the reason for the award was in the photo.
They might, but since she has constructed a novel supercapacitor, they'd be wrong. Don't let the "it's political correctness gone mad" people win.
Re: (Score:2)
But will it power my kajigger's and whatnots?
Too much current (Score:5, Informative)
My phone battery has a capacity of 2.1Ah. To charge it in 20 seconds would require a current of 380 Amps. What kind of charger could safely supply that?
Re:Too much current (Score:4, Insightful)
Your phone battery has a capacity of about 3.3V*2.1Ah=7Wh. To charge it in 20s takes 7Wh/(20/3600)h=1260W, which is about the power of a hairdryer or a microwave oven, for a short time. There may be some technological hurdles to implementing that, but safety-wise this kind of power is not a big deal in the household.
Re: (Score:2)
You would need a much thicker cable than the ordinary cell phone charger cable, and the phone itself would have to be significantly thicker than an iPhone to accept the plug, unless you accept that you can only re-charge the battery (at that speed) when it is removed from the phone and put in some sort of fast charger. (Good luck getting Apple to adopt that idea.)
Re: (Score:3)
Apple would ask the question, "if we used a Lightning connector, with a reasonable cable, how many minutes can we do it in?"
20s is great for people who want to brag, but far from necessary.
Re: (Score:2)
What order of magnitude might that be? There is nothing at all in the photo to suggest scale.
Re: (Score:2)
Again, nobody advocates pushing 380A to the device. You push 10x less to the device, and an on-board power converter steps-down the voltage. That's like power distribution engineering 101. Since the "charging equipment" on your typical motherboards and GPU cards routinely supplies in excess of 100A, I think it's a non-issue. Just because legacy technology is huge doesn't mean modern techniques can't pack it in a very small volume.
Re: (Score:3)
Re: (Score:2)
Re: (Score:2)
A charger designed to supply that sort of a current, which would be built into the phone. It's called engineering. You must have never heard of it.
Re: (Score:2)
So the charger will be a lot bigger.
Not necessarily. If the charger uses higher voltages than 12V then the size and the current do not need to be that large.
Re: (Score:2)
Re: (Score:3)
Sigh. This is 8th grade physics stuff. Power = Voltage * Current (DC values). If the cells are at 3.5V, what you do is supply the thing with an off-the-shelf telecom supply at 48V, and even with losses you only need to push 30A or so if the cells need 380A charging current. Since the plug only needs to handle that current for a short time, it can be much smaller than already-small 30A-capable contacts. It'd easily fit in the envelope of a full-size USB type A connector.
Intrigued... (Score:5, Insightful)
With the rapid adoption of portable electronics, Eesha Khare, 18, of Saratoga, California, recognized the crucial need for energy-efficient storage devices. She developed a tiny device that fits inside cell phone batteries, allowing them to fully charge within 20-30 seconds. Eesha’s invention also has potential applications for car batteries.
Will be doing some more Googling, but seriously, a link to the lab in which she worked or article/abstract published would be nice. Surely these are gifted kids, but I can't help but think the reporter really doesn't understand what she's done to write any thing more than a press release.
Charge in 5 seconds (Score:2)
Re: (Score:2)
In some European cities, street merchants and hotels would offer an exchange service for flat cellphone batteries vs. charged batteries. Rather than you leaving your phone lying around in your room plugged into the mains (and risk being stolen), you could go to reception or the street and get a
swap.
Re: (Score:2)
On mine (HTC Rezound), replacing the battery involves removing the back cover, maybe 15 seconds or so if I'm quick. Then, it takes a couple of minutes to boot up, since it was powered off.
Re: (Score:2)
We need a secondary battery to 'sleep' a device, so that you can rip out the main battery without powering on and off. :)
Terrible article (Score:2)
Is there a link to some article not in the mainstream media? The article has no details at all. Did she use an off-the-shelf super capacitor? What circuits did she make (one characteristic of a capacitor is the voltage immediately goes down as soon as you take charge from it, unlike a Li-Ion battery which maintains a more or less constant voltage through most of its charge), and how efficient is the voltage regulation? What about the energy density of the device? All supercaps I know of have a very small fr
Re: (Score:2)
Unfortunately, the is no article besides a one-page summary [usc.edu]. It sucks. That's not science, that's bullshit to me.
Forgotten (Score:5, Insightful)
What a lot of these articles forget is the current requirements to charge something fast. Just because something can be charged fast doesn't mean you can do it.
Let's take a typical laptop battery of 70 watt hours. To charge it in one hour, you need a 70W power supply (more or less). Now let's charge that same battery - if we can - in 30 seconds, or 120th of the time. You'll need an 8.4kW charger to do that, which is going to be much larger and heavier than the laptop. In Britain where the mains electricity is 240 volts, you're going to need 35 amps to do that (typical household circuit is 13 amps, high power circuits for example ovens and tumble dryers are 30A). In the United States you'll need 70 amps.
OK, so you can charge slower (but still much faster than a conventional battery) but it's still going to require a large (heavy) power supply for your laptop if you want to make the charging speed significantly faster than current lithium ion batteries. You're either going to wind up lugging around a lot of extra weight with your portable machine, or you're going to need two chargers (more expense). The thing is, the times when you really wish you can charge a battery quickly are always times you're travelling and so won't have the large heavy charger with you!
Re: (Score:2)
Now let's charge that same battery - if we can - in 30 seconds, or 120th of the time. You'll need an 8.4kW charger to do that, which is going to be much larger and heavier than the laptop.
Not necessarily. If you only need to run it about 30 seconds at full blast, it doesn't have to have the size of a PSU designed to constantly deliver 8.4kW.
Re: (Score:2)
Re: (Score:3)
No, you don't. You're making the mistake of applying existing paradigms to new technologies.
You can use a much lower power charger to charge a local supercap (inside the charger) over a longer time, then when you charge the "battery," you simply transfer that energy.
Re: (Score:2)
Transferring 70 watt-hours in 30 seconds is going to need high voltages and/or high currents, both of which are difficult to handle safely. You need heavy cables to carry 70 amps, and you need good insulation to handle 120 volts.
Re: (Score:2)
Who said anything about cables?
Re: (Score:2)
Except the target application in this case is phones which represents about 1/10th of the powerload. Suddenly you're at 840W to achieve a 30 second charge time.
But hey why go overkill? We the consumer are used to waiting for hours. Why don't we worry about small targets with smaller benefits first? Let's just charge my phone in 5 minutes. 84 watts now is less than most of my household appliances and I would be incredibly happy if we could do that.
Re: (Score:3)
It's useful even if you can't do it in 30 seconds.
How about a 1000W charger? That's about a tea kettle, perfectly doable in domestic conditions. Laptop charged in 5 minutes while you have your breakfast.
Sure, the charger will be a bit large, but you can offer both high and low power chargers. High power for the people who have a need for the laptop to be charged quickly. Low power for something you can travel with.
For cell phones it gets even easier, since quite a few can be charged from the 5W USB provides
Re: (Score:2)
Just split the difference and put a super cap in the supply and trickle charge it.
Re: (Score:2)
That's right.
So basically, all these fancy energy-saving methods we've been implementing lately have been wiped out by things that are EVEN WORSE for the grid than what we had.
Electric cars, supercapacitors, etc. all add to PEAK usage. Between 5:30 and 6:00 everyone is going to be putting their 8KW charger on, even if only for a second, and raising peak time usage (which means that even more capacity has to be brought online - sometimes for hours before and after - to cope with demand and we'll be "even mo
Re: (Score:2)
Re: (Score:2)
As far as capacitors, any capacitor can be charged in a short time. This is merely controlled by the resistor. The lower the resistance, the higher the current, the shorter the time constant, that is the time to charge or discharge 64% or the capacitor. It is an advancement that there is
FTFA: (Score:3)
"supercapacitor, a gizmo that can pack a lot of energy into a tiny space, charges quickly and holds its charge for a long time"
Ah, Not really, no [wikipedia.org]. Supercapacitor=1Mj/KG, pretty weak sauce relatively speaking.
Personally, I'm, holding out for a 'Doug Stanhope' phone with an ethanol fuel cell than 'runs on booze'.
Already there (Score:3)
The rough version is there, it's called (quite missleadingly) a second battery plus a charger that can charge batteries externally. Been using that setup for years now and it can charge a phone in seconds, as long the phone has a changeable battery.
Guess companies might be able to fine tune it, e.g. make batteries easier to eject and insert, plus add a capacitor (a normal one, that keeps the phone live for say 30s), and you've got instant charging, today.
Re: (Score:2)
Fast Charging batteries are here (Score:2)
Ten minutes to charge and off the shelf:
http://www.toshiba.com/ind/product_display.jsp?id1=821 [toshiba.com]
The reason that supercapacitors are not already (Score:2)
powering our cell phones is that in order to get the super high capacitance the "plates" of the capacitor must be microscopically close together which limits the voltage at which they can operate to typically 2.5V. The next problem is that you can't use all the energy stored because you need a DC input converter circuit to regulate (and step up) the ever falling voltage as the capacitor discharges and those circuits require some minimal level of input, maybe a few hundred millivolts, below which they cease
Re: (Score:2)
in order to get the super high capacitance the "plates" of the capacitor must be microscopically close together which limits the voltage at which they can operate to typically 2.5V. ... If this student managed to make a supercapacitor that operates at 5V or higher in the same physical volume as current technology 2.5V parts
If you could make a 5V supercap with given capacitance, which had 2x the volume of a 2.5V cap w/ the same capacitance, you'd be ahead of the game since you'd have 4x the energy storage in 2x the volume (E=1/2CV^2). I think a more accurate way of stating the point you're making is that current supercap construction doesn't give you enough flexibility to trade off C vs. Vmax, else you'd go for higher V and lower C, assuming that CV/volume remains constant.
I don't think the discharge curve is as much of prob
Replaceable battery (Score:2)
Just have two batteries. On on charge and one in the phone. It will also take 20 seconds to change the battery.
Re: (Score:2)
Capacitors have problems, and will never rule. (Score:4, Informative)
One problem with capacitors is the charge is stored a lot like water in a tank. As you use water the water level drops, in any capacitor, as you use it the voltage drops.
The governing equation is Q = 0.5 *C*V*V.
A single cell (in a battery of cells) is composed of two materials of different chemical states and they produce a constant voltage until one of the chemical states is depleted. Charging reverses this, again at a constant voltage. The charge and discharge voltages in a theoretically perfect cell are ~~ the same, in a real cell, resistance caused voltage drops and departures from irreversibility lead to differences in the charge discharge voltage. You must charge with a high voltage than you get on discharge.
A second problem, is the fact that a bulk material changes state in a cell, this inherently stores more charge than a capacitor, which is a surface layer of added charge. It is true that since the capacitor involves no change of state, that the life is more or less infinite, and because it is a monolayer of charge, you can charge and discharge at speeds limited only by the current limits of the wires.
The net result is the energy density of the best capacitors is barely as good as the worst batteries.
Battery graphs here http://tinyurl.com/autjb7l [tinyurl.com]
Capacitor graphs here http://tinyurl.com/byqbdje [tinyurl.com]
Direct comparisons here http://tinyurl.com/b9zwcdw [tinyurl.com]
As long as you design a downstream voltage regulator to use the declining voltage to power your circuit at its required constant voltage, then ultracaps will find a niche in many pieces of equipment from Cars(as a peak acceleration source) to tiny items as the sole power
Nonsense (Score:2)
SuperCaps where not invented or even perfected by some 18 year old guy. They have been used as energy storage for a long time now, in newer times e.g. in professional-level SSDs to allow a clean data flush on power failure. They are completely irrelevant as energy source for cellphones as, despite their impressive capacities in the full-Farad range, they cannot store enough energy. The primary limiter is that they have low maximum voltages. And cellphones have some minimal energy requirements that cannot be
Re: (Score:2)
So how is it that an eighteen year old girl with no science degree comes up with what PHDed scientist have been looking for for decades?
Don't jump to conclusions or buy too much into the article's hype. She made a capacitor using AFAIK a novel chemical/construction technique, and it works well according to some measures. That's a very impressive feat for a high school student, and she certainly deserves a full ride to her Ph.D. at the university of her choosing. It does not mean it's practical, which could be for any number of reasons. Maybe it's too fragile to be practical, whatever. Hopefully she'll be one of those people looking for a pr
Re: (Score:2)
Anyone remember the 1980's? Remember how the CMOS RAM on your PC's motherboard used to be powered by super capacitors before CR20xx batteries became cheap enough? Super capacitors have been around a loooong time.
Computers have been around an even longer time. Would you rather use a current model or one from the 80's? Tech improves even if the names of the devices don't.
Re: (Score:3)
There were no affordable supercaps with leakage current low enough in the 1980's your memory is playing tricks on you. The standard means used was NiCad button-cell accumulators.
You are right about the age of supercaps though.
Re:Power for the people (Score:4, Informative)
Re: (Score:3)
People tend to forget that high quantities of stored energy have an inherent danger. Laptops catching fire because of lithium-ion battery failures are usually the only hazard that people tend to remember. To truly have a consumer safe device you want something that can be charged quickly but the maximum discharge rate is closer to a conventional battery.
The point is that when you exceed a certain speed of energy release the device start