Jump to content
House Price Crash Forum

Archived

This topic is now archived and is closed to further replies.

interestrateripoff

Teen Invents Way To Charge Your Phone In 20 Seconds

Recommended Posts

http://www.nbcnews.com/technology/teens-invention-could-charge-your-phone-20-seconds-1C9977955

Waiting hours for a cellphone to charge may become a thing of the past, thanks to an 18-year-old high-school student's invention. She won a $50,000 prize Friday at 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 Eesha Khare of Saratoga, Calif.

Very impressive if they can get it all to work.

Share this post


Link to post
Share on other sites

Since when are super-capacitors something new? They have been around for ages.

http://en.wikipedia.org/wiki/Supercapacitor

There are several reasons why they aren't commonly used to replace batteries:

Disadvantages include:

* Higher price than rechargeable batteries

* The amount of energy stored per unit weight or volume is generally lower than that of a rechargeable battery

* Higher self-discharge – the rate is considerably higher than that of an electrochemical battery.

* Low maximum voltage – series connections are needed to obtain higher voltages, and voltage balancing may be required.

* Unlike practical batteries, the voltage across any capacitor, including supercapacitors, drops significantly as it discharges. Effective storage and recovery of energy requires complex electronic control and switching equipment, with consequent energy loss.

* Very low internal resistance allows extremely rapid discharge when shorted, resulting in a spark hazard similar to any other capacitor of similar voltage and capacitance (generally much higher than electrochemical cells).

Share this post


Link to post
Share on other sites

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.

It is not clear if she has come up with a new type of supercapacitor (which would be impressive), or she has used existing supercapacitor technology to come up with one that would fit in a phone (which has the flaws and limitations listed in a post above) or has simply 'invented' the flawed idea to use a supercapacitor in a phone, which would be a damn easy way of making $50K for thinking of something obvious and not very useful.

My advice is to never rely on the journalistic abiliies of a hack who uses the word 'gizmo' to explain technology.

The article does say:

To date, she has used the supercapacitor to power a light-emitting diode, or LED. The invention's future is even brighter. She sees it fitting inside cellphones and the other portable electronic devices that are proliferating in today's world, freeing people and their gadgets for a longer time from reliance on electrical outlets.

So... she hasn't used it in a phone... yet. She has a declared interest in nanoelectronics. Intel would surely not give out a prize for simply connecting an existing supercapacitor to an LED.

Which leads me to suppose that she HAS come up with some novel technology for the capacitor itself. If that is the case, she has done something very impressive. The 'mobile phone' angle is just journalistic fluff because the journalist is too dim to get his head around capacitor technology.

Share this post


Link to post
Share on other sites

It is not clear if she has come up with a new type of supercapacitor (which would be impressive, and I doubt it), or she has used existing supercapacitor technology to come up with one that would fit in a phone (which has the flaws and limitations listed in a post above) or has simply 'invented' the flawed idea to use a supercapacitor in a phone, which would be a damn easy way of making $50K for thinking of something obvious and not very useful.

This seems to have been very poorly reported. I've done some digging as best I can.

Essentially, she'd did a stint as a lab assistant with thus prof who had invented and published this new supercapacitor formulation a year before she joined him.

During her work, she helped make the prototype capacitors and test them.

After she left, it appears she built one for herself.

Share this post


Link to post
Share on other sites

My first experience with an undischarged "super capacitor" was a cathode ray tube from a TV set. I soon learned to earth the EHT/anode cap to the chassis before handling when the set was switched off! blink.gif

Share this post


Link to post
Share on other sites

My first experience with an undischarged "super capacitor" was a cathode ray tube from a TV set. I soon learned to earth the EHT/anode cap to the chassis before handling when the set was switched off! blink.gif

A CRT can store a large charge for weeks - old TVs are dangerous if you don't know what you are doing.

There is nothing new about capacitors replacing batteries. In the days back when I designed a few PSUs, we used to call everyting larger than 2700uF a 'battery' :D

Share this post


Link to post
Share on other sites

My first experience with an undischarged "super capacitor" was a cathode ray tube from a TV set. I soon learned to earth the EHT/anode cap to the chassis before handling when the set was switched off! blink.gif

I'm assuming you used the proper macho "two big screwdrivers" method, and not some poncy safety-probe and insulated bleed-resistor tomfoolery...

XYY

Share this post


Link to post
Share on other sites

There is nothing new about capacitors replacing batteries. In the days back when I designed a few PSUs, we used to call everyting larger than 2700uF a 'battery' :D

Well I can tell you that 2 or 3 of these - typically value 4700uF each - have been used for many years in car airbag ECU's as a supplementary battery.

If your car battery is crushed in a collision - which is a fairly common occurrence - your airbag might not deploy. The capacitors form what is referred to as the energy reserve, which is immediately switched in, and will ensure enough voltage and current to fire the explosive charges that blow the bags in the event of the loss of the main battery.

Not a lot of people know that...

XYY

Share this post


Link to post
Share on other sites

There is nothing new about capacitors replacing batteries. In the days back when I designed a few PSUs, we used to call everyting larger than 2700uF a 'battery' :D

Heh. That's pretty much the case.

6 2700F capacitors in place of a car battery will have no difficulty starting a 2.5 litre engine even after having the radio on for half-an-hour.

Share this post


Link to post
Share on other sites

Heh. That's pretty much the case.

6 2700F capacitors in place of a car battery will have no difficulty starting a 2.5 litre engine even after having the radio on for half-an-hour.

6, 2700 Farad capacitors would need a fair sized truck to carry them. Are you sure you wanted to drop the 10-6?

Now, lets talks about defibrillators. There's a shocking amount of energy stored in those. See what I did there?

Share this post


Link to post
Share on other sites

6, 2700 Farad capacitors would need a fair sized truck to carry them. Are you sure you wanted to drop the 10-6?

No. I did mean 2700 F. These are a pretty standard size these days, and slightly smaller than a baked-bean can for 2.5V.

Readily available on ebay

Share this post


Link to post
Share on other sites

No. I did mean 2700 F. These are a pretty standard size these days, and slightly smaller than a baked-bean can for 2.5V.

Readily available on ebay

And when I said 2700uF, I meant uF. microFarads. 'u' is used by people like me who are too lazy to cut and paste 'μ'. ;)

Share this post


Link to post
Share on other sites

And when I said 2700uF, I meant uF. microFarads. 'u' is used by people like me who are too lazy to cut and paste 'μ'. ;)

Alt+0181 (on a numberpad) will give you μ. I need to use this a lot in my job.

Share this post


Link to post
Share on other sites

I'm assuming you used the proper macho "two big screwdrivers" method, and not some poncy safety-probe and insulated bleed-resistor tomfoolery...

XYY

Nope a short length of old mains cable, first to the chassis and then the other end under the anode cap. You will then hear a small crack and possibly a flash but at least the tube is discharged. Stout boots and an insulated floor help.

The main risk is getting a shock whilst handling the tube, and then dropping the thing, which then implodes!

But I have seen proper TV engineers use two big screw drivers.

Actually old TV power supplies are far more dangerous partly because of their capacitors.

Share this post


Link to post
Share on other sites

I read an interesting article about early CRT TVs a while ago, that revealed that one particular model was called the 'widowmaker' by early TV repair men.

50kV inside. Thats a huge voltage, even for inside a TV.

Share this post


Link to post
Share on other sites

I read an interesting article about early CRT TVs a while ago, that revealed that one particular model was called the 'widowmaker' by early TV repair men.

50kV inside. Thats a huge voltage, even for inside a TV.

Just make sure you keep a few cm away and you'll be fine.

I've been using a 50kV DC power supply for my research and have now finished experimenting. I am grateful to be alive. The MoD wanted to come and do some testing with the power supply but baulked at my risk assessment, in particular the earthing mechanism. Due to the low current that was typically flowing it was only operating at around a few Watts.

Share this post


Link to post
Share on other sites
Guest eight

Nope a short length of old mains cable, first to the chassis and then the other end under the anode cap. You will then hear a small crack and possibly a flash but at least the tube is discharged. Stout boots and an insulated floor help.

The main risk is getting a shock whilst handling the tube, and then dropping the thing, which then implodes!

But I have seen proper TV engineers use two big screw drivers.

Actually old TV power supplies are far more dangerous partly because of their capacitors.

I got a shock off a motor starting capacitor a couple of years ago. It's amazing just how many swearwords you know, given some encouragement.

Share this post


Link to post
Share on other sites

I read an interesting article about early CRT TVs a while ago, that revealed that one particular model was called the 'widowmaker' by early TV repair men.

50kV inside. Thats a huge voltage, even for inside a TV.

I remember reading about those. I think you might be getting the voltage a little high, but it was certainly several kilo-Volts into lethal levels.

The really dangerous thing with these was the fact that the HT was derived directly from the mains transformer and was thus of a much lower output impedance than later designs. Lower impedance = higher current. Those air-purifier ioniser things in your house have more than enough volts to do the job, but can't deliver the lethal current.

But touch those Widowmakers with juice on and you were dead. 100% guaranteed. No exceptions.

And there were no interlocks on the back door to protect the forgetful in those Health and Safety free times.

The old saying goes that "it's the volts that jolts, but the mills that kills..." - The lethal amount of milliamps for humans was a piss-in-the-ocean to what these babies could deliver.

I want one... :)

XYY

Share this post


Link to post
Share on other sites

I read an interesting article about early CRT TVs a while ago, that revealed that one particular model was called the 'widowmaker' by early TV repair men.

50kV inside. Thats a huge voltage, even for inside a TV.

25kV for a standard set! I don't know whether that was an extra large one! A colleague of mine used to do TV repairs and e remembers somebody walking backwards into one and getting a very large burn on his back!

Why charge your cellphone, when you can steal another one? ;)

Share this post


Link to post
Share on other sites

I got a shock off a motor starting capacitor a couple of years ago. It's amazing just how many swearwords you know, given some encouragement.

Swearwords?

In that tone of voice, "beer" would be a swearword.

Share this post


Link to post
Share on other sites

  • Recently Browsing   0 members

    No registered users viewing this page.

  • 246 Brexit, House prices and Summer 2020

    1. 1. Including the effects Brexit, where do you think average UK house prices will be relative to now in June 2020?


      • down 5% +
      • down 2.5%
      • Even
      • up 2.5%
      • up 5%



×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.