alternator help

[iceteebone 5,000+ posts]

i have a 93 grand prix and i was wondering if a 140 amp alternator would be big enough for 2 rockford 1001bd amps

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[Topcat 10+ year member]

First - add all the fuse ratings of all your amplifiers. Then divide the total RMS watts by Total Peak watts and multiply this figure times your total fuse rating. This is the approximate current draw for your sound system. For example, you have three(3) amplifiers, Amp 1 has a 100a fuse and is 1000 watts RMS and 1200 watts peak. Amp 2 is 150 watts RMS and 300 watts peak with a 40a fuse. Amp 3 is 75 watts and 150 watts peak and a 40a fuse. Adding the fuse ratings gives you 180 amps. Total RMS watts will be 1225 watts. Total peak watts wil be 1650 watts. so the math kinda looks like this: 1225 / 1650 = .742 x 180 = 133.56 amps. Another good way to estimate your system current draw is to approximate 85 amps per 1000 watt.