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High output alternator swap questions

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Old Apr 16, 2007
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buggman's Avatar
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From: Dougal County
Icon5 High output alternator swap questions

Hi folks,
I'm in need of a little assistance & helpful knowledge.
I searched around the forun here, but I couldn't find exactly what I'm looking for.
I have a 96 super cab, 4.0l, 4wd, auto with all power options: fog lights, windows, locks, (had the factory stereo amp but I removed it) and such.
I have a 400 watt stereo amp now, but I'm going to add an additional 500+ watt amp and possibly a power inverter.

I'm going to upgrade my stock alternator (probably 95 amps) with a 170 to 200 amp aftermarket model, but before I drop a couple hundred bucks, I have a couple of things that I can't seem to figure out.

I traced the factory alternator wire across the motor over to the "starter relay" (at least the haynes manual calls the round electrical connection terminal - located between the battery & power distribution box). But the factory alternator wire (about 10 to 8 gauge) has a funky F shaped, plastic covered connector that connects to TWO of the terminals on the relay.

I know I'm going to need to upgrade toat least a 4 gauge wire for the more powerful alternator, but I'm not sure the deal is with this funky connector.

My alternator wire doesn't go directly to the battery, but the starter wire (about 4 gauge) does.

When I remove the old factory alternator wire, can I just connect my new larger gauge alternator wire to the first terminal (of the starter relay) and run a jumper wire (same gauge) to the second terminal?

Are there any other precautions or tricks I need to know before jumping into this job?

Thanks for any helpful info!
 
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Old Apr 16, 2007
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tekrsq's Avatar
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From: Richmond, Va
Hopefully Bob will pop in here to help you out. In the mean time, need a few pics. I'm not familar with the older setups.

Oh almost forgot, WELCOME to the forum !!!!!
 
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Old Apr 16, 2007
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buggman's Avatar
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Thanks for the reply,
I'll try to get some pics this afternoon to shed some light on the starter relay.
 
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Old Apr 16, 2007
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From: Kennett Square, PA
You'll want to run a 4 gauge wire directly to the battery from the alternator. That's what I did.

You will fuse this lead for 250 amps. You are supposed to fuse the alternator output to 25% over the max output of the alternator. I did this also. Be careful how you run this wire because no matter how you look at it, one part of it is vulnerable and unfused.

What I mean is: is you put the fuse close to the battery, you're protected in case the wire shorts from the battery burning up, but the alternator (if the vehicle is running) can still drive the wire and cause a fire. If you put the fuse near the alternator, then a short will cause a fire even if the vehicle isn't running! Mine is 1/2 way down the line, lol.

You will tape off or remove and eliminate the original power lead to the alternator.

Now, assuming the '96 uses the "3G" style -- make sure you get the "large case" 3G alternator as the upgrade and not the "small case" one. The large case one gives MUCH more power at idle.

A common problem with upgraded factory-style alternators is that although their peak amperage goes up, their amperage at idle goes DOWN.

A smaller alternator pulley can be obtained to help with this.
 
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Old Apr 17, 2007
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From: Dougal County
Here's a pic of the starter relay:


The gray wire from the alternator is only about 10" long, then it changes to a heavier gauge (maybe 8ga) black/orange stripe wire with heat shrink tubing with "fuse link" printed on it.
There's no fuse inline between the starter relay & the alternator, just the short gray wire. There's not a fuse between the battery & starter relay either.

The F shaped connector connects to both terminals of the starter relay.

I haven't had time to remove the split loom from the wires connected to the F shaped connector to see which side each wire goes on the relay. There's a small (10ga or smaller) wire that goes to the battery & a larger (4ga) wire that goes down to the starter.

The alternator I'm looking at claims to output 110 amps @ 800 rpm (idle) and 200 amps @ 1600 rpm. They recommend 4ga wire, but didn't specify where to connect to (battery vs relay) It's about $200 shipped.
I'll drop them a message before I buy to see if they have any additional info.
Hopefully they don't have a core charge either.
 
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