Power Formula

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=28604
Printed Date: May 17, 2024 at 6:50 PM

Topic: Power Formula

Posted By: Edicius
Subject: Power Formula
Date Posted: March 18, 2004 at 1:08 PM

Can some one give me the formula to calculate how many amps I will need out of my alternator depending on my amplifier setup. I had it a while ago but now I've lost it.

Replies:

Posted By: jugga-nemo
Date Posted: March 18, 2004 at 1:11 PM

watts RMS divided by the volts at idle.

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5.25" Components & 5x7 Coax Kappas w/Power Acoustik OV4-800
KAC 7252 powering 2 D3 8" Diamonds
KDC-MP728, KGC-4042A

Posted By: 00neon
Date Posted: March 18, 2004 at 9:54 PM

so can i ask the dumb question (after all im a newbie, the thing says so) how do you figure out the volts at idle?

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1 JL 12 w3 D4
1 MTX 421 D Monoblock
1 Sony Xplod 75x4
Front: Alpine SPX-177A
Rear: JL audio VR690-CXI

Posted By: Clean Install
Date Posted: March 19, 2004 at 4:26 AM

Digital multimeter

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If we learn from each success and
each failure, then we can improve ourselves

Posted By: 00neon
Date Posted: March 19, 2004 at 9:50 AM

CLEAN INSTALL wrote:

Digital multimeter

but what do you hook it up too?

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1 JL 12 w3 D4
1 MTX 421 D Monoblock
1 Sony Xplod 75x4
Front: Alpine SPX-177A
Rear: JL audio VR690-CXI

Posted By: customsuburb
Date Posted: March 19, 2004 at 10:42 PM

The average output of your alternator is 13.8 (this is without all of the acessories running though usually).

Posted By: celta
Date Posted: March 20, 2004 at 1:17 PM

W RMS/ 13.8

Ex: 400W RMS/13.8 = 28.98 Amp

Fuse = 30 Amp

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celtic

Posted By: celta
Date Posted: March 20, 2004 at 1:20 PM

try JBL GTO 17" on rear and 15" on front. Well, it´s a Sony, don´t expect miracles.I have one to.

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celtic

Posted By: Clean Install
Date Posted: March 22, 2004 at 9:38 PM

00neon here you go: posted_image

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If we learn from each success and
each failure, then we can improve ourselves

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