Charging System

Discussion in 'Softail Models' started by Charley, Jul 24, 2009.

  1. Charley

    Charley New Member

    4
    11
    0
    Hello Everyone,

    I'm having an issue with my 2000 Fatboy killing batteries. I read the previous articles posted here about testing the stator and the voltage regulator and to the best of my abilities checked them over. I followed the procedures in the service manual and which was pretty much the same information that I found here.

    I pulled the Voltage regulator off unplugged the harness to the stator and checked the voltage output of the stator while revving the bike, the output was what the service manual said it should be. I then took my test light and checked the pins on the voltage regulator and the test light didn't so much as flicker, which supposedly indicates the regulator is okay.

    Put a new battery in the bike and rode it all day numerous stops on the ride and cranked like a champ every time. I get home put on the battery tender and the thing doen't turn green showing a full charge for over 14 hours.

    In the past the charger would go green within a couple hours at most. Now I'm thinking there is no charge going to the battery while riding.

    Question I have is there another component that could be stopping the battery from getting charged? OR do I need to remove the voltage regulator from the bike and take it to a HD dealer and have it tested by them.

    I plan on getting into the service manual tonight and going through the wiring diagrams to try an find another possible point of failure.

    Any help would be greatly appreciated.

    Thank You
     
  2. gs34

    gs34 Junior Member

    639
    28
    5
    Take your meter and check the voltage across the + and - battery terminals with nothing turned on. If the battery is fully charged, you should read 12.6 VDC +/- a tenth or so.
    Now, start the bike and allow it to idle. The meter should show right around 13 VDC +/-
    Now. increase the engine rpm, and you should see the voltage increase and should eventually reach 14.5 VDC +/- by the time you are stabilized around 2500/3000 RPM
    If you do not see this increase, I would say you've got a bad regulator, just from what you have said.
    These voltages may not be exact, but they are close enough to what you should actually see to tell you what you need to know.
     
  3. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

    4,630
    68
    99
  4. Charley

    Charley New Member

    4
    11
    0
    GS and TQ thanks for the responses

    I put the multi-meter on the VR pins (one at a time) and got 1.45VDC coming through it, test light wouldn't pick it up as I suspected. What all I've read about this subject indicates the VR is bad if there is any output.

    Thanks Again!
     
  5. SpringerSteve98

    SpringerSteve98 Active Member

    187
    26
    0
    If you ground the test light at the battery, and take the hot side to the stator plug (regulator side) and see any juice at all in either hole the regulator is bad. That means the diode isn't functioning. If the stator tests ok, and the battery is still dying its almost always the voltage regulator.
     
  6. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

    8,176
    98
    16
    Charley, glad you got it sorted...I for one always like to troubleshoot with DMM over a test light when doing "leakage" tests...and they can be gotten for $10 at Harbor Freight...not like the old days when they were 200 to 300 dollars!
     
  7. Charley

    Charley New Member

    4
    11
    0
    That was it guys, put the new VR on and I'm getting 14.3 to 14.5 across the battery terminals now.

    NEWHD you are 100% correct about using a DMM, dunno why I even used my test light, according to the Service Manual that's all you need to do. LOL
    Should have trusted my better judgment and went with the DMM in the first place, instead I panicked :bigsmiley22: after the test light procedure and thought I was going to spend hunnerds of dollars!

    Maybe some day I'll be able to help someone out on this forum like you guys did for me.

    Charley
     
  8. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

    4,630
    68
    99
    As a quick note to those guys and dolls with a volt meter on there dashboard, don't put too much stock on what they read. Mine looks to be about a volt low. It looks like slightly over 13 volts when running, but I am reading 14.25 volts at the battery in idle with a DVOM. The gauge is just a monitoring tool, not an instrument. If it drops significantly from what it has been reading, that is an indicator of a problem to investigate.

    TQ
     
  9. 2wheels4life

    2wheels4life Member

    20
    1
    0
    Agreed, those gauges are for reference only, they are not precision instruments.
     
  10. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

    4,630
    68
    99
    Charley,

    Congrats!! Glad you got her sussed.

    Not sure why, but many time when either the stator or VR goes, the other is not too far behind. So keep an eye (or nose) on your stator. A tell-tale is a burnt smell of the primary fluid when you change it or even just open up the cover. You can also periodically check the resistance of the stator coils as described in the procedure I sent you earlier. If you start to see a short or even just a drop in resistance, get ready. Even with burnt coils, the alternator can read the appropriate amount of Vac.

    TQ