Big 3 in a 99 Cadillac STS Help

[Baydestrian]

Stock alt is 140amps and I just got it replaced the other day...only running 500rms but I hope to add some nice speakers and amp them and then maybe jump up to a Jl 1000/1 for my subs...

My battery is under my backseat so I have a positive post under the hood if I ever need a jump...can I run the wiring off that or do I have to run the wiring through the car from the battery itself?

[Marlo Stanfield]

What size wiring connects the post to the batt though?? Where does the alt + go to, batt under seat or the post under hood??

You can still wiring the normal big 3 just using the positive post, but IMO the weak link will be that wire that connects the two.

Edited October 19, 2009 by Marlo Stanfield

[Baydestrian]

Not too sure on wiring connect size but I'm 99.9% sure that it connects to the battery under the seat since there is nothing attached to the + post under the hood. The alt is on the side of the engine since its a special water cooled alternator

I can't really even see where the wire from it goes...I just had a shop replace it last week and just to get it out you need to flush the cooling system then remove the fan/radiator

The voltage for my car is acting weird but most times I'll get a .3-5 drop in voltage at the most so I'm thinking maybe just go for a small cap to stiffen it. I'm seeing no dimming, I just don't want to kill this alt.

Edited October 19, 2009 by wonderbreadSTS

[audiofanaticz]

With your factory battery under the seat I would:

Run a 1/0 power wire from your alternator positive to your battery positive under the rear seat (keeping the factory wire intact and still hooked up).

Run a engine ground (preferably from an alternator mounting stud) to the cars chassis/body.

Run a ground from your stock rear battery to the cars chassis/body (try and follow the factory ground if possible and ground at the same spot if you can)

Then when your ready to add amps, simply run your amps positive and negative from your amp to your stock rear battery.

Also remember you can always upgrade to a better battery later on (like a powermaster d3400)

Make sure for all ground connections on the car try to find a thick metal place to ground too (using the frame is preferred but on a uni-body type car that maybe hard).

Also remember to sand away in paint or rust to ensure a clean metal on metal connection for the least resistance possible!!

[Baydestrian]

Where would be a good place to fuse it at?

[Marlo Stanfield]

If you're fusing the wire from shorts and what not then within 18" of the connection point on the batt.

Btw follow what bangin caddy said, it's exactly where I was going with it.

[Baydestrian]

now I'll have to see if I can even get through the firewall, I can't drill through it myself

[audiofanaticz]

Make sure to fuse both ends of the power wire, by the alternator and the battery. Just 1 fuse wont prevent a short from starting a fire.

As for a hole in your fire wall, check on the driver side, behind your gas and break pedals. You will have to pull the carpet back a little bit.

Every vehicle has unoccupied holes in the firewall for running wires, or other options your car didnt come with. Sometimes you may have to make them bigger however.

[Baydestrian]

thanks for all the advice

[Soulman07]

Factory wiring size is 4 gauge... Just run the wire from alternator + to battery +.