lol, it depends on how many batteries, ive seen 7k on a stock 100amp alt, but the dude had 10 fat ass batteries. running high power needs charging but charging is nothing without somewhere to store the power.
well i plan on running a dc 5k on a 185 amp alt with 2 beefy batteries in the back. with 2 level 4 xl dc 12's
you will probably want 1 or 2 more batteries, but hell, before you spend any extra money on batteries, see how your voltage sits with just the two, if you need more, then get more.