I'm going to be using the M4-ATX 250W DC PSU for my carputer. I am going to try utilizing the standard features on the M4 (ignition turn on/off, amplifier remote signal), but am prepared to use relays if need be, since I have read many cases where the functions did not work properly.

Here's my question: I will be powering ~300 watt (4.1 channel) amp and the 250 watt PSU with my car battery. Of course, it will only be while running and I will have it turning off within 30 seconds of car shut down. Should this be a problem?

I will be powering the PC and a 7" lilliput monitor with the PSU, which shouldn't be any problem for the unit. I am more concerned with any detrimental effects that may be had on my battery due to the additional ~500 watts of strain on it.

What do you guys think?