Being new to this just be patient. When the specs on an amp say it has a 80 amp fuse rating is talking about how much current it will draw from the alternator? (80 amps from the alt?) ANd what difference would it make if your running it at higher or lower impendances? thank you
well, 80A will be the most current the amplifier can draw continuously without blowing the fuse. note I said can and not will.
that actually doesn't even mean the amplifier can draw 80A or continuous current to be honest, but generally it's a good ballpark to assume that if the amp has an 80A fuse, that's going to be about the peak current it'll draw at it's lowest load.
now as for loads, the lower the impedance, the higher the power output of most amplifiers, and thus the more current the amplifier will draw consistantly.
example for an average class D mono amplifier:
500 wats RMS @ 4 ohms = 50A of current 1000 watts RMS @ 2 ohms = 100A of current 1800 watts @ 1 ohm = 180A of current, assuming the amp is 1 ohm stable.
keep in mind this is at peak output using a signal generator and a dummy load. in reality, a "1000 watt amplifier" will really only put out about 400 watts continuously even at near peak volume levels, due to the dynamic nature of music, and the reactive nature of speakers and their voice coils.