Portable power supply

[beni_72]

Hey guys I'm not sure if this is the right place or if this site is even then right place but didn't know where else to ask and thought there'd be someone on here that would know.

I need to know how to create a cheap, convenient power supply to power a stereo.
Car battery maybe?
I don't know, whatever. Just need to get something that will last a full day.


If anyone can help it would be fantastic!!

Thanks