How big of an alternator do i need?

[Copper07]

Hey guys, Im running two amps, the Power Acoustik 4500 class D 5 channel; http://www.sonicelectronix.com/item_76636_Power-Acoustik-BAMF4500-5D.html and the and the Power Acoustik 2000/1D; http://www.sonicelectronix.com/item_76636_Power-Acoustik-BAMF4500-5D.html a double din jvs headunit, a clarion equalizer, and possible some smaller amps as well, less than 75 watts. I have Kinetic HC 600 in the back; http://www.sonicelectronix.com/item_88291_Kinetik-HC600-BLU.html , with 0 gauge for both power and ground run to the stock battery in the front (will be upgrading stock battery soon), 4 gauge run to the amps, and then the stock alt. My question is, how many amps does my alt need to put out to keep up? This is all in a 2011 extended cab, 2.9L Colorado btw. I know I can use ohms law to calculate exact figures, but I also know that those amps arent going to draw their maximum all the time. So what should I use?

-Also, does anyone know how much the trucks actual electrical system pulls, or how I can measure that?

[Esgedi]

A mechman d-series would be able to keep up with how much amperage that'd pull. You can measure power consumption of the vehicle with a clamp meter on the positive going to the fuse block, but there's a huge difference between peak amperage and sustained.

Edit: Oh. It's a colorado. Probably going to have to get a custom quote unless you want to drop $600 for an off the shelf DC.

[Copper07]

Can i get a number estimate of how many amps I need? These are the offers from Singer;

MDL PRICE IDLE OUTPUT

180A $369 140A (220A peak)

220A $399 150A (240A peak)

240A $449 160A (260A peak)

275A $489 170A (310A peak)

320A $569 180A (340A peak)

larger case (hairpin style)

MDL PRICE IDLE OUTPUT

220A $549 175+A (240A peak)

250A $569 190+A (270A peak)

270A $599 200+A (280A peak)

330A $699 200+A (340A peak)

370A $749 220+A (390A peak)

And then I can get a 240 amp for 470 from excessive amperage, or I can pick a 240 amp one up from Ebay for 256; http://www.ebay.com/itm/Hummer-Gmc-Chevy-Colorado-Canyon-H3-NEW-Alternator-High-240-Amp-Generator-/351667227999?hash=item51e1000d5f:m:mhg_K1m1xYXvwwKp-ghCCLQ&vxp=mtr which should I go with? Singer also offers a lifetime warranty on their products.

[walwalka]

^{Do you plan on upgrading at any point?}

^{Also, never go ebay. They are garbage alts and cause more problems than the amount your saved.}

^{Personally, I'd go with the 270a hairpin from singer.}

[Copper07]

Not really. What I have now is about where I'm staying. Might change brands, add a little, take away a little, but it should stay roughly the same. Whats the advantage of the Hairpin?

[hdorre]

^{Personally, I'd go with the 270a hairpin from singer.}

Same.

Whats the advantage of the Hairpin?

More idle output, less drop in output as heat is introduced, less strain on engine, etc

[Copper07]

Would I be able to get away with less? I know I don't want to jip electrical, since everything is based off it, but that is a fair amount of cash to drop lol. What is the bare minimum I could get away with, so then I could get something sort of in the middle. What math is involved to figure out what you need?

[reedal]

I would say no less than the 270 hairpin from singer. The amps you will be running are inefficient, and will require to have that extra power on tap in order to perform at their best.

But if you want to go with the bare minimum, add up the Fuse ratings of the amps, and add another 60amps, and that's how much alt you should have.

[ShadeTreeMechanic]

You could try the stock alt to begin with and go from there. Get a volt meter to install and see what it does.

[Lakeshow94]

Go with the biggest you can afford. Your batteries/your alternator will appreciate it. Not to mention the added output idle is nice. The biggest singer makes for my vehicle before suffering loss at idle is a 240. I would of gone with a 370 if I could.