Did you do the "Big 3"? Try that first before spending on a bigger Alt.

Search "Big+Three+3"
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EDIT: I did a little searching and apparently "three+3" turns up too many results so the search ignores it...

ANYWAY https://blazerforum.com/forum/showth...hlight=upgrade

The big 3 is running 3 seaparate 1/0 gauge wires from:
ALT to POS Bat
Neg Bat to frame
Neg Bat to Engine

It just "eases" the flow of electricity. You can add a 1/0 wire to ground the rear of the body to the frame if you want, but it could be considered overkill. This should ease the strain on the electrical system allowing for better charging, you won't get the dimming lights with each bass hit anymore, AND people supposedly have picked up a little bit of performance. (That may be imaginary performance though...)

 

Well I found a new 200A alternator for $130 with shipping. The specs say it is for 96-97 blazer, so I asked if it would work on my 99, and they told me it would fit perfectly. Should I give it a shot or ???? I'm in the process of doing the big three but I wasn't sure if I need to have a fuse on the wire running from the (+) battery to (+) alternator?

 

As far as I know you don't, I've seen setups and they didn't run one.

Fusing accessories is necessary becaue I've seen amp power wires draw so much they started fires. Your battery doesn't really draw, the Alt just feeds it power and charges it.

 

so, the original question was if a 15 would sound good in a blazer.

a kid in my area has a single 15 inch L5 in his 2 door and it gets loud and sounds decent. his box has a few leaks in it which makes it sloppy sounding. i personally have had 10s, 12s, and an 8 ported and sealed in my blazer. my truck is the testing vehicle when we want to see if subs and speakers work.

ported will definitely get loud and move some air but sealed almost always sounds better when going for quality music.

upgrading the alternator will help if you're pulling a ton of amperage. i personally will do it just so i have the ability to upgrade if i choose to.

i'm only pulling 1300 watts rms for 1 12inch sub and a set of components. so, with that being said... my system isn't running at the moment because i'm reworking my trunk layout

 

I met som Audio pro at a car show. He had 12 Subs hooked to multiple amps for a total of 15,000 watts all running on one stock Alternator in an Expy.
He told me that you don't need a bigger alternator, but more batteries. He has NEVER burned an alternator.

 

very true. but for most of us, the cheap and easy fix is to upgrade alternator.

running multiple batteries involves having to "hide" them, run an isolator, and running all the wiring. i've installed them before (brother's 2 cars and a couple local people) and they aren't fun but they sure as heck to the job right

 

Id do the big three before grabbing a bigger alt. Factory wiring is too thin to run the current needed for decent amps so when the amp requires 10A the wiring is too resistive and you get voltage drops. Running that 10A constantly will cause the wiring to heat up and thats no good.

 

I did the big three with 4 awg wire yesterday but I am still averaging 13v when they are hitting hard.

 

second battery? isolated? original battery charged to 14? few things to look at

 

I'm gonna build a 9^3ft vent ported box for them out of 3/4" mdf before I upgrade anything else. I'll put up pics when completed.