Whats the biggest amp I can hook up to my cars electrical system?
Your car’s alternator ampere rating determines how powerful an amplifier you can install. Multiply the ampere rating by 40%, and you’ll get a rough idea of how much reserve current capacity your car’s system has. Next, you’ll need to calculate the approximate current draw of the amplifier you’re considering installing. 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 300 watts RMS per channel would be 600 watts). Double it to account for amplifier inefficiency (600 watts X 2 = 1200 watts), then divide by the average output Voltage of an alternator, 13.8 volts (1200 divided by 13.8 = 87 amps). Since the average music signal requires about 1/3rd of the average power in a test tone, divide by 3 (87 amps divided by 3 = 29 amps). The result is the amplifier’s approximate average current draw. A fast-and-nasty way to ballpark an amplifier’s current draw is to divide the total fuse value of the amp by two. Fo
