Power Converter & Battery

I have two questions:

1.  Does anyone have any idea if there are power converters out there that have built in filters for like a PS2...some of the cheap power converters send bad signals to the PS2 causing a bad picture and sound, are there more expensive power converters that anyone knows about that provide a filtered (digital?) power source to the unit?

and 2.  If I were to mount one of the Yellow Top Interstate batteries (cold crank deep cycle) in my trunk how long would it power a screen and a PS2 before I needed to charge it back up.  I am talking about the battery alone with no alternator attached to keep it charged.  If anyone has any idea how long it would last please tell me!!

Expensive, but a Gell Cell battery would be your best bet for a constant draw while car is not running.  The console doesn't draw as much current as the inverter itself would, unless you have all kinds of things hooked up to it. 

Deep cycle is a marine battery, but a GELL works better.  Gell Cells are designed for powered wheel-chairs and other devices as such with a demand for power.  A Gell is supposed to run one for 10 hours.

Wallmart had the newer inverters with the noisless output, and they were very reasonably priced.  A 140watt inverter should be just fine, I used one for my Game Cube, no problems.  U used to leave it on all the time to power a strobe light in auto I used to have, never drained the battery.  Big Lots sells the 300watt inverter for 29.99, I use that all the time.

I use a 140watt inverter on my boat with the Gell battery, and have all days worth of use out of it.  Especially when my charging circuit in the outboard does not work, so I had to have something that will start the motor a few times a day. I also use a smaller Gell battery for the 34lb electric motor, and never drained the Gell Cell.  Gell Cells are smaller than the Deep Cycle with the same results.