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)
Gizmo? (Score:4, Insightful)
Sometimes I really hate "technology" reporting.
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: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: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.
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.
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: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: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: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: supercapacitors are cool (Score:5, Insightful)