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Diode in Alternator Wiring

Discussion in 'The Hokey Ass Message Board' started by worthop, Mar 29, 2012.

  1. worthop
    Joined: Sep 19, 2005
    Posts: 441

    worthop
    Member



    Should/Can the diode be Soldered to the wire? Or, just crimped?
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 56,013

    squirrel
    Member

    either will work, the "experts" will recommend soldering it and covering it with heat shrink.

    I'm not an expert, I think I crimped the one I put in my car 15 years ago, no problems.
     
  3. butch27
    Joined: Dec 10, 2004
    Posts: 2,847

    butch27
    Member

    I soldered mine.
     
  4. Retro Jim
    Joined: May 27, 2007
    Posts: 3,854

    Retro Jim
    Member

    Solder and shrink wrap is the best way to go !

    Retro Jim
     

  5. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,659

    Rusty O'Toole
    Member

    Either will work, soldered will still work after the crimped one corrodes and stops working. If you live in Arizona I can see where corrosion is not a problem. If you live in the rust belt and plan to keep the car more than a year, solder it.
     
  6. worthop
    Joined: Sep 19, 2005
    Posts: 441

    worthop
    Member

    I will solder, Thanks Guys!
     
  7. oj
    Joined: Jul 27, 2008
    Posts: 6,457

    oj
    Member

    There is a right way and wrong way as far as the dirction goes - it has been a while and i don't remember exactly but there is a 'band' at one end to tell you how it is biased. I believe the band faces away from the altenator, test it to see - what you need to accomplish is that power can go from the altenator but not return into it, the diode is a one-way gate and will read continuity from one direction only.
    Like others, i solder and shrinktube it.
     
    gnichols likes this.
  8. worthop
    Joined: Sep 19, 2005
    Posts: 441

    worthop
    Member

    I think the stripe side is to the alternator..
     
  9. usmile4
    Joined: Jul 28, 2005
    Posts: 690

    usmile4
    Member

    Yes stripe toward alternaotor. I crimp, solder, tape, shrink but I'm in Illinois.
     
  10. Puna Paul
    Joined: Mar 4, 2012
    Posts: 10

    Puna Paul
    Member
    from Hawaii

    Diode stripe towards alternator will block the current flow from the alternator. What's the point of having this diode in there anyway? (FNG here).
     
  11. squirrel
    Joined: Sep 23, 2004
    Posts: 56,013

    squirrel
    Member

    I had to install the diode to get my engine to shut off, when I added the MSD ignition. The MSD switch wire draws very little current, and the alternator idiot light wire backfeeding to the ignition circuit kept the engine running after I turned off the key.
     
  12. Puna Paul
    Joined: Mar 4, 2012
    Posts: 10

    Puna Paul
    Member
    from Hawaii

    Ah, that makes sense. Good to know if I switch over from points...
     
  13. sooooo....I read that it goes in the exciter wire. Cool, but does the diode get installed in that wire in front of or behind the 194 bulb?
     
  14. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,245

    2OLD2FAST
    Member
    from illinois

    Twelve year old thread
     
  15. '29 Gizmo
    Joined: Nov 6, 2022
    Posts: 791

    '29 Gizmo
    Member
    from UK

    Either.. just need it to stop back feeding the supply
     
  16. gnichols
    Joined: Mar 6, 2008
    Posts: 11,348

    gnichols
    Member
    from Tampa, FL

    Just why is that important? One of the great benefits of this site is that you can search for the solutions to your problem.
     
  17. I'd say soldering the diode to the wire is a better option if you want a more secure connection.
     
  18. Crimp using Packard Electric product crimp and pliers. Double the heat shrink. First the short piece then a longer piece. Knock on wood never. Had one fail in 20:years.
     
    54reno likes this.
  19. Jack E/NJ
    Joined: Mar 5, 2011
    Posts: 837

    Jack E/NJ
    Member
    from NJ

    A 1 amp or less bulb passes enough current to excite the alternator but not enough to backfeed the coil. No diode needed.
     
  20. '29 Gizmo
    Joined: Nov 6, 2022
    Posts: 791

    '29 Gizmo
    Member
    from UK

    Yes and no. Depends on the rest of the wiring scheme. It is potentialy enough to keep a relay energised if the ignition circuit is powered through relays.
     
    MCjim likes this.
  21. I've wired cars with diodes and others with a "alternator/generator/charge" light, or whatever you choose to call it; but never used both on the same job.
     
  22. Hellbentrodder
    Joined: Aug 10, 2010
    Posts: 210

    Hellbentrodder
    Member
    from Cotati

    Kinda off topic but kinda not. I have a battery draw on my car that I can not find. Someone said it could be a bad diode in the alternator. Is that possible?
     
  23. Jack E/NJ
    Joined: Mar 5, 2011
    Posts: 837

    Jack E/NJ
    Member
    from NJ

    >>I have a battery draw on my car that I can not find.>>>

    It's likely the alternator's voltage sensor if its wire is connected to an unswitched part of the circuit. Not unusual. Telltale sign is when you disconnect then reconnect the battery, you might get a little spark when nothing else is turn on. Typically draws less than 0.1amps. Not much. But may be an issue if the car sits for a few months.
     
    Happydaze and Hellbentrodder like this.
  24. MCjim
    Joined: Jun 4, 2006
    Posts: 965

    MCjim
    Member
    from soCal

    Right, I ended up with both light and diode.
     
  25. Vinman1
    Joined: Feb 17, 2018
    Posts: 19

    Vinman1
    Member
    from Cape Cod

    The diode takes the place of light, since I did not want the bulb. Both are basically doing the same thing, which is to prevent the back feeding through the ignition. Without them the engine will stay running with the ignition turned off. May not be the case in all wiring schemes, but mine did.
     
    bschwoeble likes this.
  26. Jack E/NJ
    Joined: Mar 5, 2011
    Posts: 837

    Jack E/NJ
    Member
    from NJ

    > >Right, I ended up with both light and diode. > >

    That's because the bulb should be connected directly to the relay's output terminal, not to its gate terminal to which the ignition switch is connected Still no diode needed
     
    bschwoeble likes this.

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