Another dumb LS1 wiring question. Alternator

macloft · #1 (**permalink**) 07-21-2008, 04:15 AM

Sorry guys I have another dumb question. I realise I dont have the alternator fully wired. I have the 2 wires going to the battery positive terminal but where does the other small wire go.
Bruce

Doubledip · #2 (**permalink**) 07-21-2008, 06:45 AM

you will have 3 postions to put wires...

1 is the big post - goes to battery +
the other 2 which are in the removable plug - 1 goes to ign + the other goes to light in dash

Tenrocca · #3 (**permalink**) 07-21-2008, 06:51 AM

Gday Bruce -

Alternators...the bane of my existence.

Finally sorfted mine out tonight. i have a L76 but am using a LS1 alternator - these are not the same. The LS1 has the battery terminal (the large post) and a L and S terminal.
The later L76\l98 alternator has a L and F terminal.

I was feeding the gen F output from the ecu to the S terminal on the alternator. After a bit of searching tonight figured these arent the same - the S from the alt needs to go to 12v (I guess is this is the one you have going to the battery also - my understanding is that it should pick up the 12v elsewhere in the loom though as a measure of average voltage through the sytem) and the other is the L terminal which is the charge light. This need to go to the battery light on your dash, with +12v on the other side of the light. This circuit also supplies startup current to the alternator to ignite it to start charging.

Hope that helps and I hope Im right - but thats is what works for me.

Cheers,
Andrew.

(Justin beat me to it

- I waffled, but we are saying the same thing)

Aussie Mike · #4 (**permalink**) 07-21-2008, 06:39 PM

I wouldn't go out of my way to buy an LSx alternator. The Units used on the GenIII are a big bulky thing that's overkill for a Cobra. I think they deliver 140Amps or something like that. Considering our cars have no A/C electric windows etc you dont need the big alternator unless you are going to fill the thing with speakers and amplifiers.

I bought an 80Amp Delco unit from the wreckers for $55 and then built my own brackets. Its a lot more compact giving more options for mounting it.

Only 3 wires needed.

1. The main output wire, you can run this one round to the main cable on your starter if you have the battery in the boot.

2. Exciter lead, this one should be hooked to ignition battery so that the alternator is energized when you have the engine running.

3. Charge indicator, this one should be hooked up to a bulb on your dash with ignition battery on the other side of it. As the alternator output voltage ramps up it will reach the same potential as ignition battery and the bulb will go out. If its over charging the voltage will be higher than the battery voltage and the bulb will light. If it's under charging the battery potential will be higher and the bulb will light. I still like to have a volt guage on the dash as well.

Cheers

Tenrocca · #5 (**permalink**) 07-21-2008, 07:02 PM

Quote:

Originally Posted by Aussie Mike

I wouldn't go out of my way to buy an LSx alternator. The Units used on the GenIII are a big bulky thing that's overkill for a Cobra. I think they deliver 140Amps or something like that. Considering our cars have no A/C electric windows etc you dont need the big alternator unless you are going to fill the thing with speakers and amplifiers.
Cheers

Ive got 15" subs going in the boot, in dash DVD, a 42" plasma instead of a windscreen and neon lights underneath - 140 amps might not be enough

Aussie Mike · #6 (**permalink**) 07-21-2008, 07:24 PM

What color Neon? Blue will set off the Taupe paint nicely.

I'm going the high performace route and sticking a bunch of those glow sticks the kids wear at the disco under there. No drag on the charging system that way.

Philm · #7 (**permalink**) 07-21-2008, 07:52 PM

Andrew,
You may have to start looking at the correct load rated tires, as you are starting with a heavy base that extra weigh may put you in the small truck class.

Phil

sideshow · #8 (**permalink**) 07-21-2008, 11:39 PM

does it come with a free homie hat that sits on at around 45 degrees of centre

macloft · #9 (**permalink**) 07-22-2008, 02:19 AM

Thanks guys. Mike (you little guru) its now crystal clear what the third wire and the bulb does. You would not believe the amount of searching I have done to find that answer. Thats why I headed it dumb question cause I felt bloody dumb asking.

sambo · #10 (**permalink**) 07-22-2008, 02:51 AM

Bruce - you mean it wasn't in the build manual??

macloft · #11 (**permalink**) 07-22-2008, 04:15 AM

I thought the Club Cobra site was the build manual. You know half the fun is the research and the variations you end up with. I dont know if I would want a build manual.
Anyway I better go wire up the alternator. Now I have to run another wire through the fire wall.
Bruce

Tenrocca · #12 (**permalink**) 07-22-2008, 04:54 PM

Hey....its us CR guys that make the build manual jokes. Stop using our material.

Everything you wanted to know about mitsubishi alternators:

http://myweb.tiscali.co.uk/jensenmon...alternator.htm

One important thing to note is the S terminal is a sense wire, and not a start up wire. The L (light) terminal provides the start up current (exciter)- so you definately need to have a battery warning light (why you wouldnt I dont know). I found this out as when I had the S terminal wired wrong - it wasnt getting any voltage through the S terminal. This made the alternator think the system voltage was very low, and overcharged as a result. If the S terminal provided the start up current, then the alternator wouldnt have started charging at all.