Voltage regulator bypass

Discussion in 'Mech Tech' started by TomEv86, Apr 29, 2018.

  1. Hi all, I'm in the middle off swapping my alternator, I've read up on how to bypass it but I've got myself confused, I have 2 plugs, one goes to the regulator and one goes on the alternator.
    So my understanding is;
    Green from the reg goes together with the blue from the reg onto D+ on the alternator.

    Red/white and black goes on B+ which is spliced together with the red cable from the reg.

    So that' the wires at the reg end...

    What happens with the plug at the alternator end? Are they just the other end of the reg cables or am I missing something?
     
  2. At the alternator end is where it connects via the brushes/slip rings to the field windings. The regulator adjusts the voltage by varying the field.
    Have been working on my alternator, one got with engine tests ok with multi meter but am getting warning light on as soon as connected so a diode must be breaking down, am going to use a 24v bulb and see if can find which one, think can strip it blindfolded by now lol, getting a working one from Paul so hopefully will be last time fitting it??
     
  3. Has your new alternator got an internal regulator?
     
  4. It was external and changing to an internal
     
  5. Sorry I wasnt very clear, I'm bypassing the regulator as the new one has one inbuilt, I think I'm nearly there with it all I have left at the alternator is the green to connect to D+ , Brown to go to earth and Red/white, black and a red that I think go to B+ is that correct?
     
  6. You'll only need two cables to the new alt: the thick B+ to the solenoid/battery, and the blue D+ cable to the warning light. You can disconnect everything else.

    <edit> Ooops, diagram is for a dynamo reg, but you get the idea...

    [​IMG]
     
    TomEv86 likes this.
  7. A better one of the external setup. As above, you just need B+ and D+ for internal reg. The alt is grounded through its case.

    [​IMG]
     
    TomEv86 likes this.
  8. I have connected the blue and green together where the regulator was, is the green cable on the plug end just the other end of the green that's at the reg?
    Also what is the red and the black cable for?
     
  9. 20180429_101432.jpg 20180429_092204.jpg
    So here is what I have where the reg was and where the alternator will be
     
  10. Here's the only pic of bus wiring with ext regulator I could find. If it's correct, leave the socket to the alt disconnected, run the D+ line (red + blue) to the alt warning light terminal to the alt light spade on the new alternator, connect the thick cable (possibly) to the main alt terminal. I'm not sure it should be red/white - sure it's red on my van.

    bus-79c-1.jpg
     
    nicktuft likes this.
  11. So I can connect the blue to the two red cables and fit a spade connector on the red at the plug end and leave everything else off, either that or fit a new red cable from the connector block so I know it's good... Sorry I think I'm over thinking it now, just don' want to get it wrong :confused:
     
  12. By the diagram it seems like that's right
     
  13. One of the red cables feeds the split charge relay so should that go to the B+ with the other battery lead? Thanks for the info @snotty
     
    nicktuft likes this.
  14. Pity I haven't got my head in your engine compartment - would be much easier ;). Diagram should make some sense, if the wiring colours are the same as yours.

    If the red cable to the split charge relay is a thin one, operating the relay coil, it should connect to D+, so the relay pulls in when the engine starts. If you connect it to B+, the relay will be pulled in all the time.
     
  15. Ah ok that makes sense I think I've got it now, the diagram has helped a lot!
    I will hopefully get it built up by the weekend ready for a test fingers crossed!
     
  16. Fingers crossed. Should be straightforward. Obvious, but be aware that the connections to the battery can shift a lot of current if they're shorted to the chassis - sparks will fly!
     
    TomEv86 likes this.
  17. Archie lives! Got him running on Monday with a couple of hicups along the way! now I just need to swap my dizzy to a vacuum advanced to get rid of the flat spot!
    Got a guy popping round this week to make sure the carb and timing is spot on then he's ready for a test drive! Not driven him in ages I can' wait!
    Thanks for all your help @snotty
     
    nicktuft, 3901mick, paradox and 3 others like this.
  18. :thumbsup:
     
  19. Soooooo, been driving Archie this weekend and everything seemed fine, then this evening I started him up and his lights and dash lights were very dim which says to me that the battery isn't charging!
    I'm going to check voltages tomorrow but is there anything else which would cause this?
     
  20. Checked the voltage while running and it' only 12.8v even at the alternator, have I bought a dud or could it be an earth problem? Checked the main earth straps which seem ok is there anything else?
     

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