# Capacitor and capacitance

Bassalisk
What is the highest capacitance ever made/achieved?

I am asking this because, when I am solving some time domain circuits, the values are given like 3 F etc. And I know that is absurd, and I really hate it because, if I didn't take electronics at home, I wouldn't have the feeling for high/low capacitance.

But anyway, what is the highest capacitance ever recorded?

Yuri B.
Achieved by the Nature, probably, recorded by the Brazilians, most probably - in the Amazonia regions.

Bassalisk
Achieved by the Nature, probably, recorded by the Brazilians, most probably - in the Amazonia regions.

That capacitance is?

janrs
If you google "5000 Farad capacitor" you'll see that there are several companies selling capacitors of that capacitance. So 3 Farads is not a ridiculous number.

Bassalisk
If you google "5000 Farad capacitor" you'll see that there are several companies selling capacitors of that capacitance. So 3 Farads is not a ridiculous number.

omg. You can store a power plant in it?!?!? :D

janrs
omg. You can store a power plant in it?!?!? :D

Yeeeaaaah, I guess 5000 F is pretty ridiculously large. Considering that if you hooked it up to a single volt of power, you'd get 5000 C ... Which, discharging in 1 second, would give you 5000 W. Nbd.

Bassalisk
Yeeeaaaah, I guess 5000 F is pretty ridiculously large. Considering that if you hooked it up to a single volt of power, you'd get 5000 C ... Which, discharging in 1 second, would give you 5000 W. Nbd.

5kW ?!?!? Thats like freakin' 5 washing mashines :rofl:

janrs
http://powerelectronics.com/passive_components_packaging_interconnects/capacitors/1000-3000-5000-farad-ultracapacitors-031810/" [Broken] of the place that sells 5000 F capacitors. It says they're for "A wide range of high-power applications, such as transportation, electric utility, material handling, industrial bridge power and renewable energy generation."

... so they could very well be powering 100 washing machines with that capacitor. :)
Although, keep in mind that it's only 5 kW if it discharges in 1 second. That's apparently not the intent, since the site also says they're for "long-operating-life energy storage."

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Studiot
5kW ?!?!? Thats like freakin' 5 washing mashines

If you are taking in washing now I have some available!

:rofl:

Meanwhile ask yourself what is the capacitance of a 200 amp hour 24 volt lorry battery?

Bassalisk
If you are taking in washing now I have some available!

:rofl:

Meanwhile ask yourself what is the capacitance of a 200 amp hour 24 volt lorry battery?

Well, using my prestigious knowledge of physics, and quantum mechanics, taking in the Schroedinger's wave equation, adding in the spin of the electrons, shape of the battery is approximately cylindric...

My final answer is I am clueless :rofl:

Bassalisk
But still what is the capacitance of that lorry battery? Must be huge.

Jiggy-Ninja
Sparkfun sells a 2.5V 10F "super capacitor", so it's possible even with small electronics components.

http://www.sparkfun.com/products/746

You not likely to ever use something like that except in specific applications though, I imagine.

Bassalisk
Gotta admit, I learned a lot of stuff through these forums... A LOT

Studiot
My final answer is I am clueless

Here's a clue

200 amps for 1 hour = 200 * 3600 amp-seconds = 200 * 3600 coulombs

Capacitance = Q/V

Bassalisk
Here's a clue

200 amps for 1 hour = 200 * 3600 amp-seconds = 200 * 3600 coulombs

Capacitance = Q/V

Why aren't we taught this example? :D

But there has to be a catch. These coulombs will released slowly right? Opposing to that 5000 in one sec?

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Jiggy-Ninja
Batteries don't have capacitance.

They have capacity, but not capacitance.

Yuri B.
BTW, the capacitance of thunder clouds is very small - contrary to what I have thought.

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Phrak
Batteries don't have capacitance.

They have capacity, but not capacitance.

in curcuiit theory an ideal battery is equally modeled as a capacitor of infinite capacitance.

Bassalisk
Batteries don't have capacitance.

They have capacity, but not capacitance.

Jiggy-Ninja
in curcuiit theory an ideal battery is equally modeled as a capacitor of infinite capacitance.
Studiot's calculation is still meaningless.

Batteries aren't capacitors.

Bassalisk
Studiot's calculation is still meaningless.

Batteries aren't capacitors.

Yes but they do store charge? Or produce it... through chemical reactions, that has a equivalent capacity

capacity is by definition: Charge/potential.

Gold Member
If you measure the rate that a Capacitor discharges through a Resistor (for instance, how long it takes for the volts to drop by 10%), you can find its Capacity. You can do precisely the same thing with a charged battery, which will make it appear as if it has a Capacitance. The difference is that one discharge will be exponential and the other won't. (The battery will be more like an approximate Voltage source.) The effective Capacitance' of the average battery that you can buy over the counter is a lot higher than the Capacitance of even a 'massive' Capacitor.

The very low internal resistance of a Capacitor gives it a number of advantages over a battery though (the fast achievable discharge time was mentioned above, for instance)

Bassalisk
If you measure the rate that a Capacitor discharges through a Resistor (for instance, how long it takes for the volts to drop by 10%), you can find its Capacity. You can do precisely the same thing with a charged battery, which will make it appear as if it has a Capacitance. The difference is that one discharge will be exponential and the other won't. (The battery will be more like an approximate Voltage source.) The effective Capacitance' of the average battery that you can buy over the counter is a lot higher than the Capacitance of even a 'massive' Capacitor.

The very low internal resistance of a Capacitor gives it a number of advantages over a battery though (the fast achievable discharge time was mentioned above, for instance)

Yes I agree, makes sense.

Jiggy-Ninja
Batteries are not capacitors!

One stores energy in the electric field between two isolated plates. The other stores energy in the chemical bonds of an acid touching two different kinds of conductive metal.

There are not even remotely the same thing. Please stop confusing the issue by making misleading comparisons.

Despite the similarity in the terms, capacitance of a capacitor (measured in farads) is very different from capacity of a battery (measured in amp-hours or joules). Comparing the two is like comparing pounds to pascals because they both start with "P".

The theory and math behind how the two work is totally different.

Bassalisk
Batteries are not capacitors!

One stores energy in the electric field between two isolated plates. The other stores energy in the chemical bonds of an acid touching two different kinds of conductive metal.

There are not even remotely the same thing. Please stop confusing the issue by making misleading comparisons.

Despite the similarity in the terms, capacitance of a capacitor (measured in farads) is very different from capacity of a battery (measured in amp-hours or joules). Comparing the two is like comparing pounds to pascals because they both start with "P".

We are talking about capacity, not capacitors :D. Capacity is by definition Q/V. A single point charge has capacity in some point around it.

Jiggy-Ninja
We are talking about capacity, not capacitors :D. Capacity is by definition Q/V. A single point charge has capacity in some point around it.
No, that's capacitance, and is completely inapplicable to batteries. It is only relevant to capacitors.

I am an extreme pedant about accurate terminology, especially when playing fast and loose with easily mixed up words can lead to confusion about two entirely different concepts, as seems to be happening here.

I'll repeat: Q/V has no meaning applied to batteries.

Phrak
Batteries aren't capacitors.

No, they are not. However an infinite capacitor is an ideal battery, which is what I said, but you did not address.

What is the dq/dv of an infinite capacitor?

What is dq/dv of an ideal battery?

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Gold Member
Of course they are not the same but the notion of an equivalent is well established in electronics. We quite happily talk of an 'internal resistance' in a component because that's what it looks like. If you have a battery in a black box, some tests will not distinguish it from a capacitor. That's what we're saying.

Phrak
Of course they are not the same but the notion of an equivalent is well established in electronics. We quite happily talk of an 'internal resistance' in a component because that's what it looks like. If you have a battery in a black box, some tests will not distinguish it from a capacitor. That's what we're saying.

Who is we?

Of course, the OP just wanted to know what's the coolest super-duper super capacitor, but that's not very interesting.