i plan to install an amp (Alpine MRP-F240, 50W RMS x4 at 2ohms) and a powered subwoofer (Kenwood KSC-SW1, 75W RMS) in the 'hidden' compartment in the hatch area... anyone see a problem with powering both of these off of the smaller (motorcycle-sized) rear battery in the corner? ... or would it be smarter to tap the battery in the front? Any advice appreciated. Thanks.
You should have no problems powering the items you listed. I just finished my install of my 10" subwoofer and 2 amps. 1 amp is over 300Watts RMS to the sub and the other amp is about 180Watts RMS to the front speakers. I've had the volume cranked and had it running for an hour or two consistently with no battery problems. The main problem i face is having the amps in the bin above the spare tire and not being able to put the cover on since the amps overheat and go into protection mode. I just leave the cover off for now if i'm going to be aimlessly cruising around for more than 30 min.
(300+180)/12=40A. Battery and DC/DC converter should adequately handle that load, as long as you don't try to power your ice chest using an inverter at the same time.
I pull 22 AMPS (peak) out of that little battery to power a 100 watt RF output ham radio transmitter. You really can ignore most of those meaningless wattage ratings for car audio systems. They often mean less than nothing and are only for marketing purposes. Oh, Presto, your neighbors and every other driver within 100 yards of your car called... turn down the volume.
