Electrical Wire Mini Starter Off 3g Alternator?

[Knowbody]

I'm about 95% done with the battery relocation on my '91 Coupe. Everything is completed, everything works. But the last two wires remaining are for the starter, and I've got a question.

Here's a run down... The car now has the Optima Red Top battery inside a Taylor sealed aluminum battery box in the trunk. 1ga welding cable with crimped and heat shrinked copper lugs provide power and grounds to everything. The OEM solenoid has been relocated to the trunk, and is mounted to the battery box, and one of the bolts holding it to the box are grounded to battery negative. The Moroso cut off switch is also mounted to the battery box, with the push/pull rod going through the passenger side backup light hole and out the taillight lens. The starter signal wire that originally mounted to the solenoid small stud was extended to the trunk, along with 1ga cable feeding power to a Painless Performance Power Distribution Block mounted inside the fender (semi wire tuck) where all of the wires originally on the solenoid are now mounted and get power. I grounded the battery to a 3/8" bolt on the body brace inside the trunk, and from the body brace to the quad shock mount. I grounded the engine block to the sway bar mount, and another on the block to the frame near the firewall, again all 1ga welding cable.

So the last two wires a remaining are for the starter. This is a mini starter and I'm running a 3G Alternator. Before I run the cable/wire from the solenoid to the starter, I figured I would give it a test. So I ran a 12ga wire from the right side solenoid post (over the car as it's just a test) to the original wire under the hood that was mounted to that same right side solenoid post. Then I ran the original 2ga cable that was on the left side solenoid post to the power distribution block. Turned the key and it fired right up.

So my concern/question is: is this OK to do permanently? I don't see why not, but I just want to pick some brains before I button it up.

Thanks

 

[90sickfox]

The block should be grounded directly to the battery.

The starter pulls a lot of amperage when cranking. It would be best to run it on its own power wire to the solenoid.

That's just my opinion and experience level. Maybe someone else here would have better input.

 

[Knowbody]

Yeah I was planning to run another ground from the battery to the block whenever I run the final starter cables under the car. I hear you about the amperage draw during cranking. Even though it worked with the temporary test setup, and cranked fast and fired right up, I do think I should run a dedicated cable to the starter, just figured I'd ask. Thanks!

 

[jrichker]

For a rear mounted battery, see below for the right way to do the job. Both ground and power circuits are shown.

Rear mounted battery ground wiring. Follow this plan and you will have zero
ground problems.

One 1 gauge or 1/0 gauge wire from battery negative post to a clean shiny spot on the chassis near the battery. Use a 5/16” bolt and bolt it down to make the rear ground. Use a 1 gauge or 1/0 gauge wire from the rear ground bolt to a clean shiny spot on the block.

One 4 gauge wire from the block where you connected the battery ground wire to the chassis ground where the battery was mounted up front. Use a 5/16” bolt and bolt down the 4 gauge engine to chassis ground, make sure that it the metal around the bolt is clean & shiny. This is the alternator power ground.

The computer has a dedicated power ground wire with a cylindrical quick connect (about 2 ½”long by 1” diameter. It comes out of the wiring harness near the ignition coil & starter solenoid (or relay). Be sure to bolt it to the chassis ground in the same place as you bolted the alternator power ground. This is an
absolute don’t overlook it item for EFI cars
Note: The quick disconnect may have fallen victim to damage or removal by a previous owner. However, it is still of utmost importance that the black/green wires have a high quality ground..

Picture courtesy timewarped1972

Crimp or even better, solder the lugs on the all the wire. The local auto stereo shop will have them if the auto parts store doesn't. Use some heat shrink tubing to cover the lugs and make things look nice.


For a battery cut off switch, see http://www.moroso.com/catalog/categorydisplay.asp?catcode=42225
is the switch http://www.moroso.com/catalog/images/74102_inst.pdf is the installation instructions.
Use the super duty switch and the following tech note to wire it and you will
be good to go.

Use the Moroso plan for the alternator wiring and you risk a fire. The 10 gauge wire they recommend is even less adequate that the stock Mustang wiring.

There is a solution, but it will require about 40' of 18 gauge green wire.

Wire the battery to the two 1/2" posts as shown in the diagram.

The alternator requires a different approach. On the small alternator plug there is a green wire. It is the sense lead that turns the regulator on when the ignition switch is in the run position. Cut the green wire and solder the 40' of green wire between the two pieces. Use some heat shrink to cover the splices. See http://fordfuelinjection.com/?p=7 for some excellent help on soldering & using heat shrink tubing.

Run the green wire back to the Moroso switch and cut off the excess wire. Try to run the green wire inside the car and protect it from getting cut or chaffed. Crimp a 18 gauge ring terminal (red is 18 gauge color code for the crimp on terminals) on each wire. Bolt one ring terminal to each of the 3/16" studs. Do not add the jumper between the 1/2" stud and the 3/16" stud as shown it the
Moroso diagram.

How it works:
The green wire is the ignition on sense feed to the regulator. It supplies a turn on signal to the regulator when the ignition switch is in the Run position. Turn the Moroso switch to off, and the sense voltage goes away, the voltage regulator shuts off and the alternator quits making power.

The fuse & wiring in the following diagram are for a 3G alternator. The stock alternator uses a dark green fuse link wire that connects to 2 black/orange wires. Always leave them connected to the starter solenoid even if you have a 3G alternator.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring
http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

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Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
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