Alternator to battery wire

[ShadowGT]

Hey.. I'm replacing the alternator, got one on the way because the old one literally started to catch fire. The wire that bolts on top is burnt up and the entire wire is melted and literally destroyed. Is there a place I can find a new one of those? I can't find it in the usual places.
Paranoid Fabrication has a positive side wiring kit with the grounding kits but it doesn't include the alternator wire. Napa, Autozone doesn't have it either so I'm at a loss.

Any help would be appreciated.. thanks.

[HeresMyMind]

since the system is NOT fused for that wire, i just placed a 4gauge wire from the alternator to the battery terminal (positive)
Ok for those who dont know the Big 3, is upgrading the wires between your alternator and batter, battery and chasis ground, and battery to block ground.

i drive a 1999 legacy so my grounds were flimsy and in pretty bad shape. so i decided to upgrade. I went to Boomzerz in Watertown and bought 10ft of 4 gauge wire. and 10 1/2" terminals. I chose black wire to hide the wiring to prevent over "Ricing" my engine bay. lol big

at home you will need a 12mm and a 10mm ratchet set up, some electrical tape or heat shrink, wire crimpers and an hour of time.
first locate the 4 grounding points. and 1 charge point

i chose:

stock ground on tranny just under intercooler for u turbo guys.
stock ground on radiator support
ground on alternator
stock ground on intake manifold

i measured out the wire from the negative post to the fender wall, alternator, and stock tranny ground. then i measured the wire from the alternator to the intake manifold ground.

also measure the wire from the alternator to the positive post on your battery.

(most car's require a fuse between this wire, but Subarus do not use one because they are negatively switched harnesses, I spoke with a tech at Chase Subaru to confirm).

add crimps to wires. and heat shrink or tape the, i chose tape because i have tons extra.

pictures:

https://sl-i.net/FORUM/images/imported/2009/08/z9toy-1.jpg
1= stock ground to tranny
2= positive to alternator
3= ground to alternator bolt
4= stock ground on radiator support

https://sl-i.net/FORUM/images/imported/2009/08/wkr4mt-1.jpg
1= stock ground to tranny
2= positive to alternator
3= ground to alternator bolt
4= ground from alternator bolt to stock manifold ground

https://sl-i.net/FORUM/images/imported/2009/08/4t8128-1.jpg
look at the comparison between stock wire from alternator to battery. its 8 gauge! the new 4 gauge wire is almost as thick as the wireloom on the stock wires!

immediate difference on my car, the idle was 100rpms lower. my volt gauge read 13.9/14 compared to 13.2 before. when i turn on my headlights my HID's warm up much faster and the volt gauge dips .5 volts and immediately goes back to 13.9. It used to stay low until i reved the engine. My stereo reception has gotten slightly better. (car wasn't moved during install). This upgrade is rumor'd to prevent dimming lights from Sub's, and is also much cheaper than a capacitor. Not sure if this is true but very common theme in threads concerning the big 3.

for the cost of 22$ for materials and 1 hour of time, this is a well worthy mod IMO. Exspecially when grounding kits from ebay use 8gauge wire, and the thicker kits cost 100+$!! N

ext is to upgrade to better battery terminals and a yellow-top

-B

[ShadowGT]

Oh man this is awesome. You're my hero. Well.. I already ordered the ground kit from Paranoid Fab so 35 bucks went in and I don't mind.

As for the alternator wire.. the instructions are great but I want to recap something before I head off and start fixing things.

One length of 4 gauge wire and two 1/2 ring terminals, one end to the alternator hook up bolt, the other to the positive side battery post. Everything else is taken care of by the Paranoid Fab ground kit.

I love the pictures and info.. if what I plan to do is correct with the Alt to Bat wire.. I'm off and running as soon as the alternator and ground kit gets here.

[HeresMyMind]

yup yup. the stock alt wires i left there also. BUT since yours are burned you should cut them off short and connect them to the positive terminal to be safe. now i can tell people im a hero woooo

-B

[ShadowGT]

Let me ask you this because I have really nothing to look at in my car.
In your picture you have the stock two wires with the new 4 gauge wire. You mentioned leaving the stock in there to be safe.

Does the single 4 gauge replace those two wires? I'm drawing a blank because I have no battery or alternator in the car at the moment.

Or from those two stock wires, one will be the new 4 gauge and one will be a new grounding wire when it comes in with the kit?

Still my hero, just sorry about the dumb question

[Grafton]

i'll chime in with an informative chart
https://sl-i.net/FORUM/images/imported/2009/09/f_chartm_f2a0e4bpng-1.jpg

My post in my members rides thread about completing the big three (http://www.sl-i.net/FORUM/viewtopic.php?p=139834#p139834)

[ShadowGT]

After hot wiring the alternator straight to the battery with the big new wire I put on I did see that with the engine running the volts going right up to 14 and a bit over according to my multimeter. Pretty neat. Now if my ground kit from Paranoid would get here.

[hobie]

Anyone know if this is valid for later models? In my 2000 the positive lead looks like it goes into the fusebox and THEN back out to the battery. I'm not able to get at the wire at this point without getting a little more destructive that I'd like (it stranded me yesterday and I'm back at my office parking lot trying to fix it before it rains).

My symptom was very similar to the OPs. Stock 2000 Legacy GT 150k mi and I've now had two alternators in a year. Both died with melted positive terminals. This time it melted the connecting bolt and the positive terminal jumped around under the hood causing all sorts of havoc.

So, I searched the forum and found the (google didn't find this thread) and it wasn't in Electrical threads of note (http://www.sl-i.net/FORUM/viewtopic.php?f=10&t=2871) but it probably should be.

Has anyone else with this configuration pulled apart their breaker box? It has a seam on the sides, but I'm leery to just yank on it until I learn a bit more. Pics would be great. I don't know where the resistance is that is causing the issue. It's either between the alt and the fusebox or between the fusebox and the battery. I can't get an ohmmeter into there without opening it up and I'm getting .2 ohm between battery and alternator.

-- Avoiding the ready, fire, aim scenario
Hobie

[hobie]

Great... Answered my own question when I got home. Found a pdf with the wiring diagram that matches what I am seeing.

Positive comes from the battery to a bus plate that splits out. The part that matches up with the alternator output is passed through a 100A short blow fuse (SBF-1) and then split once more to SBF-2,3,4 (50A each). Also it splits to regular fuses 1 (20a) and 2 (15a) and on F35 which is the input plug from the generator. On mine the generator has two 8ga white wires that go between the fusebox and the generator. So...

I'll need to get 2.5 ft of red 4Ga wire with an inline 100A fuse and I can recreate the original bus. Also, I'm going to grab a 4 ft of black 8Ga wiring to handle the grounding for lightweight stuff (fender to battery, alt to battery, radiator support) and 2.5 feet of black 4Ga to reinforce the block to battery connection. I'm really doubting we'll be seeing close 100A of draw on anything other than the started.

I could've been done tonight if I'd brought all my info AND saw this thread earlier.

Thanks for the helpful post though,
Hobie