Fast charge capacitor and Cap discharge time?

Imagine such situation:

I have one capacitor: 400 Volts 3.3 uF

I can charge that capacitor in 1 second.

Can I run a device using the energy from the cap?
I don't want to run the device directly from a battery.
I know a way to load a capacitor in less than 1 second. My idea is to run a device using only the energy from the cap. Of course, I will need to re-charge again and again the capacitor if I want to achieve that.

But... It's possible to run a device using the energy stored in a cap?

I have other question... How can I calculate the discharge time of the capacitor? Imagine I have the 400V 3.3uF cap and I want to run a 25 Watt device... How much time can I run the 25 watt device?
Sorry for my english.

Not long, how long do you want to run your 25W device? What is it?
Episode 129: Discharge of a capacitor

blueroomelectronics said:

Not long, how long do you want to run your 25W device? What is it?
Episode 129: Discharge of a capacitor

Click to expand...

Sorry for my english. I mean, how can I calculate the exact discharge time of a 400V 3.3uF if I want to run a device that needs 25 Watts to run.

Did you read and understand the link I posted?

How long do you want your load to run for? 1 second? What voltage will it stop running at?

blueroomelectronics said:

Did you read and understand the link I posted?

How long do you want your load to run for? 1 second? What voltage will it stop running at?

Click to expand...

Yes, I have read the info. It help me a lot. Thanks.

The energy on a capacitor is ½CV², thus a 3.3µF cap charged to 400V has an energy of .264 joules. Since a joule equals a watt-second, if you could use the total energy (which is not possible in practice) to power your 25W load it would last for .264WS ÷ 25W = 10.6ms.