| Originally posted by jllphan@Jul 2 2004, 02:07 PM |
You basically want to design your audio (in terms of power consumption) independent of the rest of the electronics in the car.* If you don't the rest of your electronics will "bogg down" everytime your sub amp tries to produce sufficient power for your sub to produce a 40Hz roll.
....and you need a charging system to make up for these large boggs. Wasn't he putting a 4,000W system in there? 285 amps at 14V, 333amps at 12V. So the rest of this post is based on the assumption he's gonna stick a 4,000 W amp in his car.
I never said 'don't mess with the batteries, just get an alternator,' That's bad. I probably should have rephrased "yes batteries would help." to something like "you also need to upgrade the battery system" But, you also don't want to overwork the alternator. They don't produce their rated output until the engine's revving fairly high, and that only happens at takeoff and at highway speeds (if that). At engine idle or at a 1,500 RPM cruise speed, alternators produce around half of their rated output. Another concern is heat. Electronics don't like heat. If you overwork a 120 amp alternator, constantly charging the battery system, it's going to get hot, causing it's parts (mechanical, and voltage regulator) to fail prematurely. It's all about headroom.
My stock 323 comes with an 80 amp alternator. Stock low powered amplifier, the car's ignition system, lights and cabin display units. That's about it. In all, that's probably around 25, MAYBE 35 amps. [Go add up the fuse box’s fuse ratings...] Why the extra 45 amps? The engine isn't redlining all of the time, so you can't get away with a 35 amp alternator, the engineers realized the alternator isn't going to produce it's full rating all of the time, so they gave us at least double what we need so the car would operate correctly and so we have a little headroom.
EDIT: buuhh99, if your putting in a 2,000W or less amp (class D or better), you can get away with a 120A alternator, just be sure to get a beefy capaciutor and battery.