# Size of 60 kWhr Capacitor

• posted

Some well intentioned daydreamer wants to store energy in motor vehicles with capacitors.

Does anyone know the size of a 60 kW hr capacitor?

If the dielectric failed in a crash, what size crater are we looking at?

Just some ballpark calculations.

Bret Cahill

• posted

Bigger than a car.

Bigger than a car

I am only guessing.

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Regards,

Boris Mohar```
• posted

First pass:

P=IE

60,000 watts Assume 12 volts. I = 5,000 amps.

R =E/I R = 12/5000

T=RC T=3600 seconds. C = 3600*5000/12 C = 1,500,000 Farads

And at the end of the time you only have 37% of the voltage. So you might want to icrease it an order of magnitude....

I estimate a rail car size bank of capacitors. (And about the same WEIGHT!)

Batteries are a MUCH better solution, but even these are not light at this power.

with

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|  __O    Thomas C. Sefranek   WA1RHP@ARRL.net```
• posted

Using a typical Maxwell boostcap ultracapacitor the volume will be around

6000 us gallons, the weight around 29,000 kg.

Dream on.

• posted

No, but apparently capacitors of the order of 1000F or so can be made surprisingly small these days, through doing clever things with "rough" surfaces that have a high surface area. This sort of thing does turn out to possibly be useful in automotive applications. (I just came back from a meeting at an automotive research place that mentioned them.)

Well, that's a good question: I read your article before going to the meeting, so I asked. Apparently it would be quite a bang. (-:

-- Mark

• posted

with

Sure - but 1000F at what working voltage? High capacitance per se is NOT the goal of what Frank ("ferrguy") THINKS he's doing, but rather energy density. And thanks to the way that energy storage depends not on capacitance alone, but rather the amount of charge you can hold >>>at a given voltage meeting, so I asked. Apparently it would be quite a bang. (-:

There was a wonderful tale along these lines in George O. Smith's classic "Venus Equilateral" series of SF short stories, back in the

1940s. In one of these, an experimenter needed some unreasonably high capacitance for some reason or other, and promptly whipped up a new "super-dielectric" - that just happened to be a fluid. Our Hero comes across this set-up, with all the glassware that made up this "super-cap", does a quick calculation as to what would happen to the voltage across the thing should the dielectric leak out, and promptly orders it dismantled...:-)

Bob M.

• posted

(snip)

(snip)

I'm afraid I don't know - I know they could get a good few hundred amps out for a bit, at presumably some sensible voltage, and at least it was credible enough, from the point of view of their simulations and their knowledge of what could be made, that it seemed a useful thing to investigate, but I didn't ask at /what/ voltage. ):

(snip)

(snip wonderful tale (-:)

Indeed.

-- Mark

• posted

with

The cap' holds 216MJ. This is equiv' to 0.05 tons (112 lbs, 1cwt, 50kgm) of TNT. At the burning rate of TNT, this is equiv' to a 30' crater.

• posted

If thats "Ferguy" don't waste your time. I think he's a troll. He has no propsals that make any sense and has had this explained to him many times. After a few weeks he's back to restart the same EER thread. He talks about making better capacitors that store energy using "inner space" whatever that is - he never explains.

Capacitors ARE being used to power prototype busses and vans in Japan (and the USA?), they have also been used as battery replacements for applications like starting diesel motors on trains - but Ferguy isn't interested in these. Try a web search on "super capacitors".

with

• posted

with

• posted

: The cap' holds 216MJ. This is equiv' to 0.05 tons (112 lbs, 1cwt, 50kgm) of : TNT. At the burning rate of TNT, this is equiv' to a 30' crater.

High voltage capacitors discharge at much higher speed...

Bye

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Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt```
• posted

In article , snipped-for-privacy@aol.com mentioned...

note last paragraph:
FAQ:

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###Got a Question about ELECTRONICS?   Check HERE First:###```
• posted

Maybe vehicles could get their power from the road. A capacitor might take you a mile down the road between stations.

snipped-for-privacy@cs.com (FEerguy9) . . .

Sounds like that would increase the size as well as the likelihood of the crater.

Nevertheless I think it's worthwhile to research, even if you don't get too far.

Just do the test crashes out on a field.

Bret Cahill

• posted

But of course, you never say HOW. Your whole "innerspace" idea is silly in the extreme, and CANNOT increase energy density, as has been shown to you many times. It increases CAPACITANCE, but at the expense of working voltage, for ANY dielectric. So you lose in the energy density. Get it? (He asks, utterly without hope of success...)

Bob M.

• posted

Yes but how? That's what everyone who ever worked on capacitors wants to achieve. Not least those designing capacitors for things like cell phones and other mobile devices. They need small caps too.

My house could do with the same treatment.

• posted

Right - and note that the basic "cell" is still going to be 10F at TWO AND A HALF VOLTS, in a package of 24 x 33 x 4.5 mm (or about 0.22 cubic inches).

E = 0.5CV^2 = (0.5)(10)(2.5)^2 = 31.25 J

A basic carbon-zinc "AA" cell provides over 5,000 J and is about half a cubic inch - so this "ultracap" has not quite

1/80 the energy density of this very old, practically obsolete dry cell technology.

Bob M.

• posted

Using 18 x GP3300 NiMH cells you can make a battery which holds 132,000 Joules and weighs just over 1Kg. (1.1Kg to be precise). 132,000J is about as much energy as is released by 30 grams (one ounce) of TNT when it explodes.

• posted

If you want to see a really big battery look up the Saft website. They have installed a UPS in Fairbanks, Alaska that can supply a load of 40Mw for 15 minutes.

as

explodes.

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