Alternator size?

I read on a thread here about a rule of thumb about how to gauge how big of an alt to upgrade to judgeing by how many total amps my amplifiers are rated to pull. I remember somthing about if 25% of the total fuse rating on the amps is over 50% of the rating for the alt you would need a bigger alt. I can't find the thread I was reading last week. The amps I am looking at ahve a total fuse rating of 200A. I have a 130A stock alt right now. If I need to upgrade my alt, I just want to get one that give me enough juice, maybe a little extra.

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Pioneer DEH-P980BT, Zapco DCREF1000.4,Pioneer TS-C520PRS, Adire Extremis, MTX TA91002, TC Sounds TC-3000 15"

Rule of thumb for alternator size is 125% of total current draw of all accessories in the vehicle. If your stereo and all other accessories adds up to 250 amps for example, you ideally want an alternator rated at 312.5 amps minimum.

~wirewise~

Damn! I guess I'll have to rethink some things since the highest alt I've seen for my Disco is 225A. Now you said "ideally", I know the amps won't be pulling their rated amps all the time, just on musical peaks right? Could I get by with 225A alt, with a total system fuse rating of 200A, along with a capacitor(2 farad), big three upgrade and good battery?

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Pioneer DEH-P980BT, Zapco DCREF1000.4,Pioneer TS-C520PRS, Adire Extremis, MTX TA91002, TC Sounds TC-3000 15"

wirewise is right. if you're refering to the total fuse rating being the total af all the fuses in the amps, at continuous use, they won't run at that. those ratings are generaly at max power. if you only have a 130a alternator, considering the amperage the amps will run continuous plus the amperage the vehicle uses, i.e., lighting, HVAC, EFI, etc, etc, i'd say at least a 200a to be on the safe side.

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Whatever you do, DO NOT let the white smoke leak out of the wires.....

an example of the "total fuse rating" (total of fuses in the amp) would be my amp having a (3) 30a fuses for a total of 90a. my amp only continuously draws around 45a.

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Whatever you do, DO NOT let the white smoke leak out of the wires.....

I was speaking to an alternator shop and the guy said to me that the stock alternator is calculated/designed to handle 25% more output than the vehicle can consume with all accessories on high. Meaning he has approx 32 amps to play with there if he has everything on full blast.  Now he needs to make up 170 amps somewhere if his amps are always pulling 200 amps, but thats unlikely, I would say maybe 100 amps average draw from them meaning approximately he should have to add 70-100 amps ontop of what he has already.  My guess would be 200-230 amp alternator will satisfactorly do the job :)

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

A cap wont really help for your situation....it is as another member here has stated over and over again "a bandaid for a bullet wound"