ok heres the scoop
acouple of other guys and me have entered our cars in a car show
if aloud i might leave my stereo going just to give the display some beats
just wondering whats the best way to do this so i can keep my battery alive?
would a battery charger be ok or do i need something else?
any info would be great, cheers

I thought Paulie was organising an iverter, so the cars could be run off the mains power?

yeah i think he is, but this is just a backup ;)

You could splash out and install a second battery, heres a link showing how, will cost about $500 though:P:
http://www.aussiemagna.com/forums/showthread.php?t=66816

This is what you want.

http://deutronic.com/battery-chargers/430-watt.htm

They're not cheap though!

find your competitors car, steal his battery