Ok. i have been hearing some things on here like: i will have to get a new alternator, battery and 1/0 awg wire for a system thats amp is pushing out 900w rms at 2 ohms. However, i have went to 2 very reputable local auto shops and they have both said that my current set up will be fine for 900w rms, no doubts. my car is a 96 civic ex, with stock alternator, basic battery, and 4 AWG wiring that i was told was good up to 1000w rms. Keep in mind these are very reputable local shops. So, my question is basicly, whos full of shiit and whos not?
The real answer depends on the efficiency of the amp. Likewise with power wire size. To calculate the current draw of an amplifier, multiply the number of channels by the RMS watts per channel (a 2 channel amp rated at 500 watts RMS per channel would be 1000 watts). Double it to account for amplifier inefficiency (1000 watts X 2 2000 watts), then divide by the average output voltage of an alternator, 13.8 volts (2000 divided by 13.8 145 amps). For more accuracy, use the actual efficiency ratings. Since the average music signal requires about 1/3rd of the average power in a test tone, divide by 3 (145 amps divided by 3 48 amps). This is an average approximation of current draw and it can go higher. So I would gather between *48 and 72 amperes for this example. Calculate 40% of the amperes of the alternator you have now. This is the average current the car uses when running (lights, accessories, etc.). Add this number to the approximate average current draw (*48), and you will come up with the actual size of alternator you need. If the number you come up with is the same or less as what your alternator supplies, you need to take no action. All of this is to keep the car efficient without taxing the electrical system. If 2 pro audio shops don't know this, then I'd be looking elsewhere. The figure of 40% is an inflated 25% as speced by auto manufacturers. I went with 40% as a precautionary measure for those who may have EXTRA accessories not part of the stock system - better safe than sorry. If you don't account for the car audio challenged, who will?
You went to the local auto shops and asked them? Being truthfull they're not going to help much but yeah you should be ok if the car is going if the off and your doing parking lot listening than your car will die in like 10 minutes if you dont do a lot of parking lot listening just upgrade the cable 2 o guage wire
