For a little more serious approach, a lead acid battery has an EXTREMELY LOW internal impedance, along with most rechargable batteries it will happily supply enough current to destroy itself.
500A certainly sounds possible, particularly if you buy a heavy duty battery, but like everyone else - I'd like to know why you feel a need for this amount of current?. Bear in mind, it's got a good chance of destroying the battery, and probably whatever else you connect to it, also what are you planning for connecting it? - you will need short, extremely thick, wires to avoid limiting the current through the wires.