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Technical Powermaster Alternator Issue

Discussion in 'The Hokey Ass Message Board' started by Dooley, Jun 28, 2020.

  1. Dooley
    Joined: May 29, 2002
    Posts: 2,677

    Dooley
    Member
    from Buffalo NY

    I moved in the insulation... Caught that when I posted.
    When I ran the powermaster I was running it one wire.
    When I changed back to Delco
    I added the plug in
    One wire goes back to battery and the other to a switched 12 volt source
    I think that's where the black one is going so I think I screwed them up
     
  2. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 571

    MAD MIKE
    Member
    from 94577

    Even with a high amp unit the single wire setup doesn't work well with high loads on a street car.
    Some of the one wire units that self excite at/above a given rpm can also turn themselves off below a given rpm. So you may not be getting charging when the engine returns to idle.
    Some of the PM units can also function as a proper 3 wire unit if the rubber plug is removed and the side terminal is plugged in. But you will need to verify if your PM unit is able to do this.
    The other wire on the side terminal(#1) should go to a switched source, such as the ignition switch.
    If you are not using a charge indicator lamp, you should at least run a 10Ω resistor in series to properly excite the alternator. So that is fine.
    Terminal 1 should go to a switched source.
    Terminal 2 should go to the main power bus for voltage monitoring.

    Also check your alternator to crank pulley ratio.
    Want to make sure your alternator rpm is correct for effective charging.
     
  3. dan griffin
    Joined: Dec 25, 2009
    Posts: 475

    dan griffin
    Member

    Single wire alternators use a magnetized rotor to provide initial field currant, if you have to tap the throttle to make it start charging that means the rotors magnetic field is not as strong as one that starts charging immediately. Field currant comes form alt. output, so if at idle you have a 40 amp load and a 23 amp output you are running off the battery, no big deal right. For a short time it is fine but here is the problem, at idle with no load 14.4 volts with load as above 11.5 volts. As the car sits at idle the system voltage continues to drop. Alt. output is dependent on field current input. Now alt. output has dropped to 15 amps the battery picks up more of the load so what is the problem. As the battery be comes more discharged system voltage keeps dropping ,alt. output keeps dropping and then its lights out.
     
  4. PhilA
    Joined: Sep 6, 2018
    Posts: 910

    PhilA
    Member

    I've only worked with the 10SI on my car (63A version, stamped) and at 350rpm with the original dynamo pulley it will not charge- engine RPM up to about 500 and it charges about 30 Amps. Lights do brighten up and it regulates to 14.4 Volts once the battery isnt taking much of a charge any more. I have the warning light wire through a 1.2W bulb with a 5W 50 Ohm wirewound resistor in parallel. With just the bulb it would take revving up to about 1200rpm to get it to begin to charge.
    Sense wire goes to the battery terminal on the starter solenoid.

    Does sound like the battery is getting disconnected from the lights circuit- if the alternator doesn't have the stabilization of a battery and only itself for reference it'll fly way high in volts (18-20) because the regulator can't regulate itself properly. The 10SI should regulate to about 15V due to the design of the circuit unloaded without battery but the voltage won't be smooth or particularly stable. A current drain like all the lights will help but I agree with the others, you've got a fault somewhere in the car's wiring that needs to be addressed before changing things out again.

    20200705_121127.jpg
    That's the general gist of the wiring in my car. The battery connection primarily terminates on the light switch. From there everything else connects, including the alternator output.
    If you've got the alternator wired to the wrong side of the switch then that would make sense of what is happening.

    Phil
     
    Last edited: Jul 5, 2020
  5. Dooley
    Joined: May 29, 2002
    Posts: 2,677

    Dooley
    Member
    from Buffalo NY

    As I see this
    Main batt wire off of kill switch
    #1 goes to switched 12 v with light inline.
    #2 goes back to same lug on kill switch that feeds my circuit panel


     
  6. PhilA
    Joined: Sep 6, 2018
    Posts: 910

    PhilA
    Member

    Alternator output should be on the battery side of the kill switch, not the load side (unless I read what you meant wrong).

    Phil
     
  7. Dooley
    Joined: May 29, 2002
    Posts: 2,677

    Dooley
    Member
    from Buffalo NY

    No I had the output on the load side...thanks
     
  8. PhilA
    Joined: Sep 6, 2018
    Posts: 910

    PhilA
    Member

    That's just from a kill switch perspective- wired on the load side all that switch will do is prevent the vehicle from being started; throw it and you disconnect the battery but the alternator continues to power the vehicle, making it a not-kill switch. (Other than toast and kill any electronics you may have connected to the alternator side, such as a tachometer, etc).

    It should, wired as you say, if switched on, not have the effect you describe. Switched off with the engine running it would though.

    Phil
     
  9. Dooley
    Joined: May 29, 2002
    Posts: 2,677

    Dooley
    Member
    from Buffalo NY

    Kill switch is wired this way.
    Power from positive to switch
    Other end of switch to starter, alternator and fuse panel.
     
  10. Dooley
    Joined: May 29, 2002
    Posts: 2,677

    Dooley
    Member
    from Buffalo NY

    here is what i did
    Batt post from alt is wired to battery side of disconnect switch
    the wire that i had looped back tot he batt post is now hooked to the starter/load side of the disconnect switch

    the other wire goes to the hot side of my coil, only powered when the key is on.

    upgraded headlight relay
     

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