# Re: Big Capacitor?

```Hi folks,

I think the key here is something that hasn't been mentioned yet. The
size of the cap is a function of the total energy storage of the the cap
as measured in Joules and the energy density of the particular type of
cap. The total energy stored in a cap is calculated with the equation
E=(F/2)*(V^2) where E is the total energy in Joules, F is the
capacitance in farads and V is the voltage. ( I hope I remembered that
correctly) Energy densities vary with the type of construction I.E.
electrolytics have a different energy density than a foil cap. I believe
that the highest energy density record is held by the relatively new
Maxwell powercache capacitors. I have seen a rectangular cap about the
size of a 12 oz coke can with a rating of 2500 farads, yes farads! and
rated at 2.5V

B.T.W if I mis-remembered that formula, someone please correct me.

Safe Coiling!

Phil Heslin

--snip--
> I have a question or two for any one out there. How big would a capacitor
> have to be, (physical dimensions), to have a value of 1 Farad? I know that
> voltage rating would be a determining factor, but just a ballpark figure.
> Has anybody ever seen one?
> Just curious.

```