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Big Capacitors Answered

I found a big capacitor in a floor cleaner...I think. It is a black cylinder with two leads off the end. In the floor cleaner, it was hooked up to a lot of stuff in a really important looking box that had a lot of wires flying everywhere. It looks sort of like the thing below, but a little smaller. So, really, there are two questions:
1. Is it a capacitor?
2. If it is, what can I do with it?
Thank you!

41 Replies

user
Goodhart (author)2013-04-16

Some Info on start / run motor caps:

An esxample:  a high rated capacitor may be used to start a particularly large electric moter (once electricity is supplied to both mothor and cap).  That "punch" gets it to move, OR to adjust a motor as it runs.

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basementhacker (author)Goodhart2013-04-17

But that motor is run on batteries or AC power right?

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user
Goodhart (author)basementhacker2013-04-17

That's the point. It is another "use" for capacitors.

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user
Goodhart (author)2013-04-02

Are any of the specs on the side similar to this?

220uF

 or:   1 F

(the number can be different than what I have listed, but the micro farad and farad rating should be on the side).


Like this.... 

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user
basementhacker (author)Goodhart2013-04-02

What would be considered a "big" capacitor? I'm going for 2 12V capacitors to run a 24V engine.

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Goodhart (author)basementhacker2013-04-03

IF you mean big in potential, than the one or two farad super capacitors are the biggest. IF you mean in size....I have seen them as large as a 5 gallon bucket already but not much in the way of capacity.

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basementhacker (author)Goodhart2013-04-03

I meant big in potential/power carrying-ness. A 5-gallon bucket strapped to a bike probably isn't going anywhere. :)

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Goodhart (author)basementhacker2013-04-05

The "smaller" they are however, the less voltage they can handle, many times.

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basementhacker (author)Goodhart2013-04-06

OK. So get big (er) ones and wire them in series?

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Goodhart (author)basementhacker2013-04-06

That is only voltage TO them. I have a one farad and a two farad capacitor that are about as big around as a quarter, and close to as thick as my finger. You would not want to discharge it across you hand :-) . Another note: you are aware that, when you put resistors in series, the resistance "adds up", but when you put them in parallel, things get complicated.

The same thing, in reverse, happens with capacitors.  In parallel, you add the capacitance up, but in series; figuring the capacitance becomes "complicated".

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basementhacker (author)Goodhart2013-04-07

Wow. This is really hard. OK!
Thanks!

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Goodhart (author)basementhacker2013-04-08

There are some short cuts, if you use capacitors etc. of equal value (farads, not load voltage....you never want to put more voltage through a capacitor then it is rated for).

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basementhacker (author)Goodhart2013-04-08

Sooo two or three capacitors of equal farad value in parallel with the voltage below/at the capacitor's rated top voltage = a battery? I'm still trying to figure out how the video below worked. It looks as though the capacitors are in series...

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Goodhart (author)basementhacker2013-04-11

in other words, the discharge is closer to a static shock than the extended discharge of a battery.

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basementhacker (author)Goodhart2013-04-12

Gooooottt it. So that's why the battery thing the guy below made works? Because its always being charged by the car/solar panels?

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Goodhart (author)basementhacker2013-04-15

The car would have to start on the first revolustion or so, and I am just not sure a cap can crank out the amount of amperage necessary to do that. If the car had to turn over 4 times before starting it could never work (I don't see how it can anyways).

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basementhacker (author)Goodhart2013-04-16

Okay. So caps are for quick discharges and zapping things. Got it.
Thank you!

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Goodhart (author)basementhacker2013-04-09

Think of it this way, "some" desktop computers have a 1 or 2 farad super capacitor in them to keep the internal clock running until a battery is replaced after removal. That does not take much to keep a digital counter rolling for a few minutes; my watch runs for 10 years without battery replacement.....

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user

No way. The caps will not store enough energy to do much at all. A LOT of research is going on to change that, but we're not there yet,

Steve

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basementhacker (author)Goodhart2013-04-02

I actually have no idea. I'm in Japan on exchange right now, and the capacitor-like-object is sitting in the STEM lab at school. What do the specs mean?

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Goodhart (author)basementhacker2013-04-02

Farad is the measurement of the "capacity" or more accurately, the "potential" of the capacitor. MOST often it is in micro or pico farads. A farad is a LOT of energy potential.

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basementhacker (author)Goodhart2013-04-02

So is this guy good?
http://www.overstock.com/Electronics/Lanzar-1.6-farad-Power-Capacitor/3519149/product.html?cid=123620

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user

Well, I was thinking of running two in series as a 24V battery pack for a go kart/electric bike/ something like that, maybe with a solar panel to keep the charge up. Would it be able to handle the draw from a motor like this:
http://www.razorama.com/groundforce-motor.html

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Goodhart (author)basementhacker2013-04-03

a 1.6 farad capacitor can hold 1.6 farads of potential. The voltage rating is how much voltage you are allowed to use (it is best to stay a bit below the max) on it. The lower the voltage applied, the slower the cap. reaches full capacity.

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steveastrouk (author)Goodhart2013-04-03

"potential" means VOLTAGE, not energy. The maximum voltage that cap can take is 450V

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Goodhart (author)steveastrouk2013-04-03

Yes, you are correct, it is potential voltage, but not "stored voltage" as some would think. I got my terms mixed up (I was thinking kenetic energy, which is more like energy potential.

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blkhawk (author)2013-04-02
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Goodhart (author)blkhawk2013-04-09

There is a lot seriously wrong with this....

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basementhacker (author)blkhawk2013-04-02

Thank you soooo much! That's a brilliant idea. My problem is that I only have one.
Thanks for the idea though! I was thinking to use it for some sort of battery, but couldn't figure out if I need more complicated electronics too.

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steveastrouk (author)2013-04-04

Forget it. The technology isn't up to it yet. For one thing, the maximum voltage 1 can handle is usually limited to less than 3V, so you need a minimum of 8 for 24V, and the amount of energy they can store is hugely less than a battery. If you read Blkharts recent thread on the subject, I showed that a battery holds 100X more energy than a capacitor, and costs less too, unless you get very lucky

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user

OK then. Is there anything else you think I can do with it?

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user

Isn't that kind of like a tazer?

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user

No its kind of like a gun.

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user

Oh...I don't think my mom would be very happy with that... :(
It sounds really cool though!

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caitlinsdad (author)2013-04-03

So the big question is, will it stun?

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Goodhart (author)caitlinsdad2013-04-03

Well, it may in one way or another. One way is if it works....the other is if it works but not well enough (then the builder would be "stunned" ;-)

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Kiteman (author)2013-04-02

I can't quite make out the text, but if you google for phrases from it, you should get your answer.

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