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JackGrat2
JackGrat2
11/14/2013 11:09:31 PM
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Newbie
Re: How about a bit of lateral thinking?
As an engineer, we call that small chemical package a "Primary Cell". Most people prefer "Secondary Cell" over single use batteries. Supercaps are used anytime volatile memory is used and it is desired to hold the data store. Many systems use flash memory to avoid a bulky supercap. Systems with time clocks that can't be stopped are an example of the remaining holdouts.

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JefW
JefW
11/14/2013 3:58:49 AM
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Newbie
How about a bit of lateral thinking?
You can solve this problem easily with a supercap pretty much as described.

Stop focussing on charging the phone with electricity.  Charge it instead with a small chemical package (a lithium ion battery).  Now you just need a supercap that can run the phone for 20 seconds to prevent any outage during the break-before-make battery swap.

Now the problems have moslty been solved and the key technology required is mechanical design to facilitate battery swap without risk of incorrect insertion etc.

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SunitaT0
SunitaT0
10/29/2013 3:13:23 AM
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Master
Re : Power Your Smartphone Forever! Charge It Instantly! Or Not
Hand Turbine Smartphone Charger is a sort of charger. Charge your smartphone with a casual hand turbine, and this comes with an AM/FM weather aware radio too. This is perfect for outdoor usage.

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JackGrat2
JackGrat2
10/2/2013 10:02:00 PM
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It was lacking any critical review

I was surprised at the broad claims and the lack of any critical analysis. The abstract does have some useful data describing the charge density as 203.3mF/cm2 and 238.5F/gram. How they arrived at 20.1Whr/kg is not explained. The article does not claim a 20 second recharge of a cell phone, just that 20 seconds of charge was used to illuminate a LED. The extrapolation to the cell phone was hyperbola. Getting a capacitor to provide operating power for a cell phone is not trivial. QuantumScape sounds like they are going to try. 

Lets return to your 1230mAh battery. Q=It=CV=4.428kCoulombs . The cell phone typically operates from 3.7V down to 3.3V at discharge. That delta of 0.4V is your working V. A similar capacitor would need to be 11.07kFarads if operated over the same voltage range. That capacitor would weigh 46.4 grams, and cover 54.45kcm2 of surface.

Assume we charge this supercap from a another supercap. This 11.07kF capacitor would be precharged to 4.1V. When connected to the phone's capacitor at 3.3V, the two then reach balance at 3.7V. Let's assume that the current is some how regulated and charges the phone in 20 seconds. That would be an average current of 221.4A. 

At the start of the charge cycle, the source capacitor had a stored energy (E=0.5CV^2) of 93.04kjoules, and the cell phone had a 60.27kjoules residual charge. After the charge cycle, both capacitors are at 3.7V, and 75.77kjoules in each. The source gave up 17.27kjoules, the phone absorbed 15.5kjoules, and 1.77kjoules was radiated into the ether. That is 88.5watts for 20 seconds. Someone can call the FCC.

 

That doesn't account for any resistive and switching losses. Obviously a capacitor is not equivalent to a good battery. We could assume some perfect form of DC/DC conversion and squeeze as much residual charge out of the capacitor, but we will still lose power to radiation every time we move charge from point A to B.

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WKetel
WKetel
10/2/2013 6:41:37 PM
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Artist
A few details are missing, it seems.
Part of the claim is certainly valid: Supercaps are much more enviromentally friendly, since the main ingrediant is carbon. And they are good for a whole lot more discharge-recharge cycles, there is no question about that.

Now the fast recharge is a bit more undecided. Batterys recharge by reversing a chemical reation, which winds up producing heat. And I have seen batteries exploded from excessive charging input. So there is a very definite limit as to how fast a battery can be charged if it is going to last very long. Now supercaps charge by polarizing a capacitor, and the rate of charge is limited primarily by the heat produced as current passes through the internal resistance. This heat is quite a bit less than the heat produced charging a battery.

But the shortcoming of a supercapacitor is exactly the same as the shortcomings of using a regular capacitor, which is that the output voltage drops as the thing discharges. That is different from a battery, where the voltage does not drop much until most of the reacting chemicals have reacted. So the system can be designed to only utilize the top of the RC discharge curve, leaving a very large portion of the stored energy unused, or else the system can have additional circuitry, such as a step-up voltage regulator, to compensate for the dropping input voltage. The penalty is greater complexity, additional expense, and somewhat lower efficiency. But the advantage s being able to utilize a much higher portion of the energy stored in the supercapacitor. So there really is the potential of using a supercap to power a cell phone. Self discharge during storeage is a reality, but most cellphones are switched on most of the time, so it may not be an issue for most people.

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jaybus
jaybus
10/2/2013 4:06:34 PM
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Newbie
Re: Science Fiction -> Fact
Sure. To stop a 1000 kg car from 20 m/s dissipates 200 kJ by heating up the brakes. If the supercap can truly take a charge current of around 150 A, then they could probably be used as intermediate storage buffer for regenerative braking.

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Maciel
Maciel
9/30/2013 1:16:40 PM
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Newbie
Re: Science Fiction -> Fact
The basic principle in my view and has the 2 layers so you can store energy for longer, being more efficient, makes it very close to a super cap.

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Vishal Prajapati
Vishal Prajapati
9/30/2013 1:22:46 AM
User Rank
Master
Re: Science Fiction -> Fact
Thank you sir, for your pointers they are really helpful to understand the basics of the super cap. I want to know is the double layer caps are super caps or stacking of these double layer caps become a super caps?

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Maciel
Maciel
9/28/2013 2:58:57 PM
User Rank
Newbie
Re: Science Fiction -> Fact
When we think of batteries, remember the electric car ... This is the great challenge of automakers increase battery life ... But on the other hand, imagine a long distance trip where there is like recharging the vehicle and in the middle of nowhere ... to the damned car, goes without energy ...

Imagine u take from his pocket a few minutes SuperCap and "resurrect the car," I see this happen with cell phones today, maybe in the future for all who need a good battery and a load that is not possible.

Some informations powerfull about the supercaps:

http://www.digikey.com/Web%20Export/Supplier%20Content/Elna_604/PDF/elna-principles-of-electric-dbl-layer-caps.pdf?redirected=1

http://www.murata.com/products/edlc/tech_guide/principle_feature/index.html

http://www.panasonic.com/industrial/includes/pdf/EEC-EP_ER_RG%20NewProduct.pdf

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Netcrawl
Netcrawl
9/28/2013 9:32:06 AM
User Rank
Master
Re: Science Fiction -> Fact
There's always some new developpment, with semiconductor manufacturers pushing the boundary of limits, not only the speed of our mobile devices, but their battery life as well, the latest development is a tiny supercapcitor that is small enough to fit inside a smartphone battery and charge it fully within 30 seconds.

Besides just smartphones and tablets, this technology has huge potential it can be applied to even higher capacity batteries like those found in automobiles.

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