over a 600 watt one....we had a guy in circuitcity the otherday and he wanted to hook one up....a 600w one didnt work but i would think an 800w one would do it...and as far as i know the converter is the only way to do it because the voltage comming out of the car is DC and the PS3 runs off AC....so eather way it needs to be converted some way...the easiest way to do it would just do the power inverter...

just my 2 cents

Rob