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Projects 90amp alternator, what wiring upgrades

Discussion in 'The Hokey Ass Message Board' started by Rustytoolss, Apr 2, 2014.

  1. Rustytoolss
    Joined: Jul 27, 2009
    Posts: 252

    Rustytoolss
    Member

    I am replacing my old mopar 35amp 12v alternator, with a 90amp nippendenso unit which has an external regulator. What wiring needs to be updated when I replace the alternator ?
    I was thinking of leaving the harness as it is/ then adding the needed extra wiring to the system (like a piggy back type system thing). Anyway what wiring will need to be upgraded ?
     
  2. I don't see why you would need to upgrade your wiring unless your putting in a huge stereo or TVs . Yes. The alternator is capable of putting out more but won't unless it's needed. 90amp isn't a lot by today's standards.
     
  3. Rustytoolss
    Joined: Jul 27, 2009
    Posts: 252

    Rustytoolss
    Member

    The reason I'm installing the larger alternator is because I've added a Vintage A/C system. And installing a backup electric fan. (my main fan is a mechanical clutch fan)
    I was unsure if I would need to increase the wiring load to things like Ignition switch, headlight switch...just unsure what wiring could use some updating because of the higher amp alternator.
     
  4. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547

    stimpy

    the output lead on the alt you should bring up to modern standards of 10 gauge to main connection of the battery ( some run it to the large stud on the starter , some to the feed in to the selinoid /relay . as for the other wiring , 14 gauge which I think mopar used . for Items that do heavy draw I try to hook to the battery for a power source and relay the items to control them .
     

  5. ^^surely upgrade the main lead to the battery and to be safe add a fusible link in that line. Probably a 14ga fusible that you can get at any parts store. Fans draw a bunch of amps so run it thru a relay to the battery with a fusible link on the feed. The temp sender will fire the relay, the relay will fire the fan. Wire a manual switch in to the relay fire lead and you can override the sender and manually turn on the fan FWIW
     
  6. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,856

    Mike51Merc
    Member

    It's the appliances that determine the load, not the power supply. In other words your new high-capacity alternator is like a huge battery. It just sits there until an appliance calls for power.

    Any new stereo, air ride, or other high-draw appliance needs heavy wire. Everything else just remains the same.
     
  7. mustangsix
    Joined: Mar 7, 2005
    Posts: 1,297

    mustangsix
    Member

    All the same with one exception. If your battery ever goes dead or near dead, the alternator will crank out a bunch of amps to charge it. The main lead from the alternator to the battery needs to be sufficient to handle that without getting too toasty.

    A 10ga feed might suffice, but an 8- or even 6-ga wire would be better insurance.
     
  8. 325w
    Joined: Feb 18, 2008
    Posts: 5,629

    325w
    ALLIANCE MEMBER

    Your new alternator has an external regulator? Asking because most of the new stuff has an internal. If external you will need a correct for the alternator regulator won't you.
     
  9. Rustytoolss
    Joined: Jul 27, 2009
    Posts: 252

    Rustytoolss
    Member

    Yeah the nippendenso uses an external reg. The stock mopar electronic is whats used.
     
  10. Rustytoolss
    Joined: Jul 27, 2009
    Posts: 252

    Rustytoolss
    Member

    Thanks Guys ! you just made my wiring project a whole lot simpler.
     

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