The Charge of the Ultra - Capacitors (Sexy capacitor pics!)

Spectrum / IEEE ^ | Nov 2007 | Joel Schindall

[spunkets]

"those are about the size of a quart of milk. "

Right. Caps have an equivalent series resistance(ESR), which determines the amount of current it can handle w/o heating up and exploding. The smaller caps always have a higher ESR, than the larger ones.

[pepsi_junkie]

The article indicates that their goal would be (amongst others) to create a capacitor which could hold so much charge for its size as to make batteries irrelevant. This would, i presume, allow for much lighter products and I know for certain that the military would drool over something lighter in weight than conventional batteries that could power small devices soldiers must carry on the battlefield. Big money there.

But on the the physics! Capacitors discharge exponentially when put to a load. That is to say, the lose their charge very rapidly! And if that load is, say, a short circuit, they lose their charge explosively (literally). How does one use capacitors for energy that must be used over a long period of time? I'd have to guess that some sort of voltage controlled impedance load that would vary the load between a very high state to an operating state to allow the capacitor to discharge in pulses of current or some such thing. Probably something completely different would actually work but that's my gut reaction. Still some science to be done!

[domenad]

If they could somehow interlock two layers of nanotubes, separated by a super-low permittivity layer, they could cut the distance appreciably between the two. Halve the distance, you double the capacitance. I have no idea how to do it on the microscopic level, but when you look at what they accomplish with VLSI, it's hardly impossible.

That said, I live for the day I can hoist two middle fingers very proudly towards Mecca and tell the sandeaters I no longer need their oil.

[Dr. Bogus Pachysandra]

During the Disco Era (or error), I built neon dancefloors and lighting and sound for discos. We made these strobe lights that used the landing strobes from 747s. The chassis had two 660 volt, oil-filled can caps. The caps were the easiest thing to grab to lift the bare chassis. I forgot to put the bleeder circuit on a chassis, grabbed the cans to move it to another bench, and got ZAPPED! All my limbs straightened out with such force, that I threw the chassis into the block wall and almost folded it in half. I was propelled across the room in the opposite direction! Had a headache for a few days! Course, I was also the four year old who stuck his fingers in a wall socket. Electricity really doesn’t bother me anymore. I seem to have developed immunity!

[saganite]

Been done. Here you go.

http://pesn.com/2007/07/30/9500477_Hiddink_propulsion/

[Erasmus]

So long as the Chinese don't steal then screw up this recipe, and we get even more bad caps (with vent goo) in our stuff.

Funny you should mention it.

Several years ago, a Taiwanese PC motherboard company experienced widespread failures of their boards out in the field.

It turns out that they had electrolytic capactors with 'youthful' mortality problems. Just enough to pass factory final test, and get into the hands of users and work for a while before going kaputt.

The capacitors were bought from a component manufacturer who offered a really low price. Too low. A young engineer, a capacitor whiz, had just come to that company from a competitor. He had brought with him the special formula for the electrolytic mixture--sort of like "Jack's Secret Sauce."

Problem was, he didn't have the full formula. He didn't know about an additional component of the chemical mixture that was necessary to keep the caps from self-destructing.

IIRC, it cost one or two companies their existence.

[rednesss]

I’ll be sure to wait and see how these things stand up to the rigors of an automobile and be especially interested in the crash survivability data. Nothing like being in a car when you get T-boned and several million volts decides to let loose.

[Erasmus]

Most or all of these applications will feature a DC-DC regulated converter that isolates the ultracap from its load. When discharging, the converter ‘makes up the difference’ as the cap decreases in voltage.

However, the efficiency of power conversion, which may be as high as 90% at high cap voltages, does indeed decrease as the cap voltage decreases, so there is a limit where the converter has to say, “no more juice available—shutting down now.”

Regenerative recharging of the cap requires yet another DC-DC converter, hooked up opposite the the discharge one. Their mutual operation must, of course, be carefully controlled. [They probably have designs which can share components between the two functions to decrease cost and size.]

[reagan_fanatic]

One of life’s simple pleasures as a Test Technician at Digital in the late 1970’s was placing a big screwdriver across the poles of a large capacitor. Safety Glasses please.

One day back in High School electronics class we were testing the charge/discharge rates on these huge, honkin' electrolytic capacitors. After everyone had discharged them, one of the kids got up to use the restroom. While he was gone, we charged his capacitor up and put it back on his desk.

About three minutes later, we hear this BANG and see the kid go flying off of his stool.

We were such rascals then ;)

[polymuser]

IIRC, it cost one or two companies their existence.

From what I read back then, it was a cause of very widespread board failure in many consumer electronic products (mobos, vcrs, vidcams, TVs), with many manufacturers not being open about the cause and unwilling to honor warranties because of the massive cost impact.

[o_zarkman44]

Awesome research. Sounds like a good prospect for more efficient delivery and storage of energy.

[glorgau]

Finally, a taser worth it’s name...

[Red Badger]

The Teaser Taser?.............

[Red Badger]

John Galt's motor in Ayn Rand's Atlas Shrugged worked on that principle.............

[isthisnickcool]

American Ingenuity Will Come up with a way

[RobFromGa]

bookmarking.

Please add me to this ping list!

[RobFromGa]

An interesting series of short articles from the Skeptical Optimist!

Here are links to all seven articles in the energy series:

• Article 1: Energy facts, certainties, and possibilities
• Article 2: Government spending and its consequences
• Article 3: Yes, growth DOES require more energy
• Article 4: Dissenting from Mr. Gore
• Article 5: The obstacle to oil independence
• Article 6: A tankful of electrons
• Article 7: A 21st Century “GI Bill”

[UCANSEE2]

Here’s what human ingenuity has come up with so far.

http://peswiki.com/energy/Congress:Top_100_Technologies_—_RD

Companies are already making ultracapacitors.

There are other technologies.

The Chevy VOLT is one of the best. Batteries with a small engine to recharge them.

There are motors out there that could make it so you could go thousands of miles before having to ‘fill up’.

Here’s one. It was invented over 30 years ago.

http://peswiki.com/index.php/Image:Bourke_30_Cubic_Inch_2_Cylinder_Engine_110.gif

[T Ruth]

Neat article. (your # 35)

[Pete from Shawnee Mission]

I thought you were kidding. This was better’n a new Victoria’s Secret Catalogue!