Electrical Battery Moving To The Trunk

Discussion in 'Fox 5.0 Mustang Tech' started by f8tlfiveo, May 31, 2013.


  1. f8tlfiveo

    f8tlfiveo My wife likes my spool and blow-off valve.

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    Has anyone moved their battery to the trunk in a convertible? If so did you buy a kit or just buy a box and wire separately? Is there a writeup on this anywhere?
    #1
  2. mikestang63

    mikestang63 Mustang Master

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    Used a taylor battery box, shutoff switch, and wiring kit like this.

    http://www.streetsideauto.com/p/taylor-48104/

    Here is how I did mine with the exception of a 175 amp fuse and 4g wire from the alt to the switch. You can use welding cable as well. It's much cheaper to buy the box and then the wiring from either a local welding company or Home Depot.

    [​IMG]
    #2
  3. RangerJoe

    RangerJoe Advanced Member

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    Jrichker has a diagram that prevents you from having to run the large power wire from the alternator to the battery cutoff switch. It utilizes an 18ga wire, run from one of the pigtail wires of the alternator. It works too. I did mine this way, and it kills the car while running. I don't have the diagram handy, but I'm sure it will turn up in a search.

    Joe
    #3
  4. FoxMustangLvr

    FoxMustangLvr Mustang Master

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    What's the benefit for moving the battery to the trunk other than cleaning up the engine bay?
    #4
  5. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    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.

    [​IMG]

    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.

    Ignition switch wiring
    http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

    Fuel, alternator, A/C and ignition wiring
    http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

    Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
    http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

    Vacuum diagram 89-93 Mustangs
    http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg



    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.

    [​IMG]


    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 [​IMG]

    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.
    #5
  6. reldla1996

    reldla1996 Member

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    IMO, the best benefit of moving the battery to the trunk is moving the center of gravity rearward, which improves handling and traction.
    #6
  7. f8tlfiveo

    f8tlfiveo My wife likes my spool and blow-off valve.

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    This and I am doing a single turbo on that side so having some extra room wouldn't hurt.
    #7

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