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The Charge of the Ultra - Capacitors

Nanotechnology takes energy storage beyond batteries

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Comments (5)

Interesting technology and article. Comments and questions:
1. Your engineering skills may be great, but I question your historical knowledge. "Capacitors have been around since 1745, beating batteries to the scene by half a century." Primitive but effective batteries (wet cells) are documented from the ancient Egyptians 3-5000 years ago and several other civilizations where they were used for metal plating and possibly other tasks.
2. What's effect does EMP have on your capacitor technology? How would you effectively shield your technology from EMP without reducing its efficiency?

Thanks. d

Concerning your article's title: Aarrggg!!

Seriously, interesting stuff.

Mathias Faust:

One fact that is only implicit mentioned but worth mentioning it explicitly is that the discharge curve of a Ultra-Capacitor is still a exponential and far from what a battery shows.
This limits the use of Ultra-Capacitors for applications where a fixed voltage is needed. Also the energy stored in the low voltage area is not accessible to such applications.

In a robot project we used five Ultra-Capacitors from Maxwell Technologies in series (about 13V peak) and a DC/DC converter to power the electronics (5V) of the robot. It worked fine, but as combined down/up converters are hard to find, the energy below 5.5V was not available. This limited the usable energy stored in the Ultra-Capacitor board to about the energy of a 9V battery. Lacking a power supply which could deliver more then 30 Amps the recharching only took about 30 seconds.
Quite buzzing to charge a small energy store with 30 Amps!

Very interesting article about a very interesting subject.
But in my opinion it is a bit inappropriate to write "... all form of capacitors store energy only on the surface of the material.".
In my knowledge electric charge is stored on the surface, whilst energy is stored where there is electric field, i.e. in the space beween the plates, since the energy density is \frac{1}{2}\epsylon_0 E^2. Isn't it?

Harlan Dutton:

I have often wondered if it might be possible to control the discharge of large capacitors. Because they can be charged very rapidly,they could then be used either as primary a supplier or as a means to recharge a battery pack over a longer period of time. This would make electric cars more attractive by lessing the time required to recharge the battery pack.

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