SUB WATTS

There's not a simple answer. The battery can supply 500+ amps on a short term basis, but doing this for any extended period will quickly drain the battery and quickly shorten its life. The Prius inverter has a 100 amp fuse, and outputs about 80 amps maximum. I wouldn't install a system that draws more than the system can continually supply. Conservative would be to limit it to about 60 amps, so that the battery isn't drained by the Prius' electronics (which probably have a power draw of around 20A due to all the processors, lighting, etc.), even if you're running near maximum power output.

60 amps * 13.8 volts = 828 watts maximum draw. However, you need to keep in mind the efficiency of the amplifiers you're using. Most car amps are class A/B, which are about 60% efficient at maximum output, so 828 * .6 = 497 watts rms (so basically 500 watts rms). If you install a class D amp, it will be about 80% efficient, so 828 * .6 = 662 watts rms. Maximum power ratings for amplifiers should be ignored (and rms numbers highly questioned - the Boss amplifier I have has been tested and has an rms output of about 1/3 of what it's rated!).

You can certainly run a much higher power system, but if you turn it up to maximum volume you could be draining the battery faster than the inverter can keep up. I'd keep to about 500W rms generally and 650W rms if using a class D amp.

The system in my Prius has about 280W rms maximum power output and can hit well over 105dB cleanly. This is more than loud enough for my needs.

 

long before you reach the maximum wattage that the car can stand the hatch will rattle so loud it will sound like $#!+. one member did just that. he downloaded a vid of his hatch vibrating loudly. if it sounds terrible, what's the point other than to annoy other drivers? 1 12" sub is way more than this car would ever need because it is small inside and kinda flimsy.