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Melting Wire - 82 Seca Turbo

Discussion in 'XJ Technical Chat' started by Masterx, Mar 26, 2018.

  1. Masterx

    Masterx Member

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    Had a friend help me get my bike going this afternoon, and as she was idling this happened:


    IMG_20180326_165623.jpg

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    Any idea where this goes to based off the location? It's alongside the battery compartment towards the bottom.
     
  2. bensalf

    bensalf Well-Known Member

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    the three white wires on most xj's are the alternator charging wires, they go from the alternator to the reg/rec .
    it seems there was a poor connection causing the plug to burn up it can be replaced by snipping it out and replacing the crimp and plastic plugs with new ones. its quite a common fault
    stu
     
    XJ550H likes this.
  3. XJ550H

    XJ550H Well-Known Member Premium Member

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    ^what he said

    3 white wires is usaly the voltage regulator/alternator there are 3 white wires that go to alt.
     
  4. XJ550H

    XJ550H Well-Known Member Premium Member

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    wiring diagram white wires run from alt to voltage reg and to diodes and relays check the diodes they may have failed
     

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  5. Masterx

    Masterx Member

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    Thank you so much. I love this place. This happened just over an hour ago and I already have an answer. :)
     
  6. XJ550H

    XJ550H Well-Known Member Premium Member

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    that is what makes it the best bike website on the internet.
     
  7. JeffK

    JeffK Well-Known Member

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    Dang XJ, don't be so humble about this site<LMAO>, I sent him over here from the TURBO forum because I knew you guys would treat him right and this board is much more active, but don't go thinking my Kaw triples board isn't the best on the 'net! KTOG (Kawasaki Triples Owners Group)


    jeff
     
  8. MattiThundrrr

    MattiThundrrr Not a guru

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    Them's fighting words, Jeff!
     
  9. ManBot13

    ManBot13 Well-Known Member

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    The more important question is WHY this happened. Alternator wires can melt from a poor connection, which increases the resistance at the connector and produces heat. But they also can produce heat and melt if there's too much current flowing through them. You need to check the health of your battery and the red and brown wire connections as well.

    The alternator on these XJs is a field coil generator, meaning that the magnetic field that is generated in the rotor is produced by an electromagnet. The rectifier/regulator (RR) duty cycles switched power voltage(brown wire) across the brushes in the rotor in bost the magnetic field that generates current in the stator. The RR senses the performance of the charging system based on the voltage measurement on the brown wire, but feeds current to the battery via the red wire.

    When the RR senses a voltage below 14.3V, it increases the duty cycle, and when it's above 14.8V it lowers the duty cycle. This can lead to a few issues. If there is a large voltage drop between battery terminal voltage and switched power voltage (due to resistance along the switched power circuit), the RR can over charge the battery, and melt the red wire. Also, if the battery is bad, and supplying it with current doesn't increase it's voltage, it'll keep increasing the duty cycle. Either one of these can produce too much current out of the stator (three white wires).

    I had the latter issue, about 600 miles from home, where my battery was getting weak and I got stuck in stopped traffic. The bike ran the battery down, and when I got moving again the battery voltage didn't come back (I installed a voltmeter on my dash to watch the charging system). After some hard riding, hoping to see the battery come back, I stopped, got a new battery and spliced the red wire which had melted. Still the battery wouldn't charge, and I found that the connector had melted. The RR never sensed it's regulated voltage, so it just kept increasing the duty cycle, producing too much current at higher RPM. Cutting out the connector and splicing those wires got me home. I rewired that section in the harness (white and red wires), moved to LED bulbs to reduce the drain on the battery when idling (the alternator is pretty weak at idle) and everything is working fine now.
     
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  10. JeffK

    JeffK Well-Known Member

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    Thanks for your explanation Manbot. I've read of using other R&R's to shunt the surplus charge as heat but haven't done it to mine since most trips are an hours or two at most on my Turbo.

    Hope all is well brother!!


    No worries Matt...all in good fun!


    jeff
     
  11. Rooster53

    Rooster53 Well-Known Member Premium Member

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    Very nice explanation ManBot, the only exception I believe is that the Rectifier Regulator used on the XJ series would be considered a linear regulator as opposed to a PWM (Pulse Width Modulated) regulator. The latter is a more efficient design in that less power is wasted as the circuit becomes a high impedance in the off state (no pulse). With the XJ, instead of a varying pulse the level of DC voltage applied to the field coil (rotor) will change to regulate the output of the AC generator.

    The shunt regulator is another design altogether, and I believe it is the least efficient as unused power created by the generator is simply shunted to ground and consumed as heat. And, I believe they are typically found on charging systems that incorporate a permanent magnet rotor.
     

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