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Why is this cap so big?

So I am installing a new stereo in my truck (I have done custom, high-end installs for years) and am including a power cap as I always do. These caps are standard in the mobile audio world to keep your headlights from dimming and to keep your alternator from being over-worked.

Question: Why are these things so big? I mean, the 10F super cap is just slightly bigger than a "standard" cap where as this one is almost the size of an oatmeal can at only 2 farad.

Just for some additional info, this particular install has a final output of around 1600 watts total.

Why is this so big?!?!?

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RobotFreak's picture

Here is the answer.

Remembers me at a russian Matrioshka doll. Guess what is inside the smaller cap. ;-)

rik's picture

Is it a tiny smoke bomb?

RobotFreak's picture

It will act as smoke bomb when you reverse the polarity of the smaller cap before reassembling it.

 

djhesit8's picture

this is a 12V cap :) btw :D It is usually used in cars audio system for the bass system to don't kill the engine/battery when a big bass drops is comming... I think, it has to charge really fast because drums could be at fast BPM...

Chris the Carpenter's picture

Man, I just love good answers!

Next we can move on to if fire has mass or not...

OddBot's picture

Imagine having this huge powerfull system and only a couple of tiny supercaps to smooth the power, like a huge bull with tiny .....

Like Telefox and the Ganster said, higher voltage and cheaper price than supercaps.

 

Benbo231's picture

Plasma weapons are right around the corner...

nmcclana's picture

What telefox said.  Super caps have a very low voltage tolerance (6V or so), but your tanker probably has a much higher voltage limit.

Sometimes bigger caps are just cheaper, too.

TeleFox's picture

Supercaps are made to be used as comparatively long-term power sources, in the same way that you'd use a small battery. Their high capacitance-to-volume ratio comes at a price - primarily that they've got a low charging voltage tolerance, and in general aren't as tough.

That huge cap you've got there is probably an electrolytic type, with a much higher voltage tolerance. Electrolytics can handle reasonable voltages (you can get HV versions too though), but you have to make them pretty big to compare to a supercap in terms of capacitance. They're also quite easy to manufacture, and they can take more of a beating - a must for automotive applications, as I'm sure you'll agree =D.