I'm going to install a High output alternator 250A and also going to replace the three wires(Alt to battery, engine to body and battery to body) should I have the wire from alternator to battery fused? I'm going to use 4ga wires(25mm2)

 

That's a good question.
The OEM alternator is rated at 110A, so the alternator you are considering is capable of charging at more than twice that rate, possibly heating up the battery 4-times as much as the OEM alternator does (heat = R * I**2). It seems that the answer depends on the battery at hand - can it take the heat, and how does its internal resistance change under load/heat.
In either case, I am subscribing to this thread.

 

Why are you upgrading to a bigger alternator? Unless you're running some crazy competition stereo, the stock alternator charges just fine. 4 gauge isn't nearly big enough to see the full benefits of a 250amp alt and larger battery. You really need to run 1/0 or even 2/0 to actually see the full benefits.

 

I'm not sure how much the battery can take. That's a little outside my wheelhouse. However, any fuse you put in the line (below 250A) will most likely pop pretty quickly as soon as you rev it up. A fuse isn't going to lower the amperage. It'll just pop if the amperage exceeds the rating of the fuse. Once that happens you won't be charging at all.

I'm also curious what you're putting together.

 

I wouldn't install just to have HO alternator so yes I'm small by small making my car audio project.

At the moment what I have installed
Hertz hp802(A/B class) the reason for early Alt upgrade
Connected to 2x Hertz sx300d(wired to 1ohm,800w each)
Hertz hp4
Connected to 2x Hertz hsk165(front) + 2x audisson voce 6,5x
Around 6meters 1/0(50mm2) fused(300A) from battery to distribution block( inside 2x150A fuses for each channel) , from there 2ga(35mm2) to hp802 4ga to hp4. Both amps have ground wire 1/0(50mm2)
Total around 2100w with both amps for now.

 

Okay, well basically I just discovered that maxima already has 4ga wires

 

Isn't charging current limited by the regulator? A larger alternator should only deliver more current when demanded by accessories.

 

Yeah it's unlikely that a 250A alternator would cook a battery, as it should regulate its voltage and current, but it is possible. If he's running his stereo for several hours with the alt pushing full amps into a small battery, he will fry the battery. Besides that, the OP is going about this all wrong.

You need to upgrade to a larger AH, deep cycle battery first. You're not running baja with full lights on for 12 hours. You're just running a medium stereo. A deep cycle battery will give you a better buffer with the stereo on, with the alt charging normally.

You need to do more research. Upgrade your battery, do the "big 3" upgrade (4gauge will do no good), if you're still running low on volts, then look into a bigger alternator.

Why did you think you needed to install a bigger alt in the first place?

 

Already amps HP802(its an A/B class amp) asks 100A and HP4 45A + car own electrical needs, deep cycle battery in on its way also, and the project is going to be bigger anyway in future.
the bigger alternator was recomended on one car audio forum.

 

Yes thats right, consulted with couple of friends about that and got the same answer.

 

I was one of the judges at a big autosound contest in Houston back in the mid-'80s. It was held in the Astroarena, lots of fun and great sounds. Good luck with your project!

 

Im still new to all this competition level sound systems and still long way to go with my project but learning as much as i can thanks