Charging System Issue

Discussion in 'Softail Models' started by 2000FLSTC, Aug 8, 2009.

  1. 2000FLSTC

    2000FLSTC New Member

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    I read the posts from Glider but still ahve a few questions/comments. Sorry for the long post.

    About 1 month ago I was riding my 2000 FLSTC when the speedo quit working, engine light came on, and digital odometer went blank. At idle everything worked, but when I increased the RPM everything quit working. I figured by speedo was going out until the other day I was riding to work and smelled a sulfer smell comming from my bike. That afternoon I went out and the bike would not start. I figured I had more problems than just a bad battery. It was 3+ years old, so I went ahead and replaced it with one from Harley so I could get the bike home. One the way home I figured out that if I turned my driving lights on the speedo would work, engine light would go off, and odometer worked. I hit the switch a number of times just to be sure. When the lights were off nothing worked, and when they were on everything worked. My theory is that the charging system is overcharging (hence the bad battery and sulfer smell) and the high voltage causes the speedo to freak out. The draw from the lights drops the voltage enough to allow the speedo to work. I ran some test on my charging system and this is what I found:

    - Voltage across the battery at idle is 17.6v and I can get to go over 19v if I rev the engine. (FAIL)

    - I grounded my test light and checked both pins of the regulator and got no light. (PASS)

    - I checked for continuity between ground and each pin of the Stator and had none. (PASS)

    - I checked resistance accross both pins of the stator and got 0.4ohms (???)

    - I checked AC voltage across the Stator and got 30-40volts at what I guess to be 2000rpm (I do not have a Tach). (PASS?)

    If I rev the engine I can get the AC voltage to go above 80. Is this a problem? I am guessing I was up around 5-6k rpm, but not sure. Should the stator output voltage reach a peak?

    I replaced the stator less than 1 year ago with one I bought from JP cycles, and the rotor with one I bought from harley. The regulator is still the original. What else should I check?

    Thanks!!
     
  2. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Use your DVOM to test the bleed back on the VR rather than the test light. Test light is not sensitive enough to show a minor bleed back.

    Checking for a short on the stator, you said that you have infinite resistance on each pin to ground, right? Across the pins you have 0.4 ohms. This is a bit high if you have the 32 amp system. Ok for the 22 but high for the 45 amp. What did you put in?

    You should be getting 16-20 Vac/1000 rpm (32 amp). So the output from the alternator seems good. But you are getting WAY too much Vdc out of the VR. It should not put out more than 15 Vdc (I think the actual number is 14.8) at any RPM. I agree with you that it probably fried the last battery. I suggest changing it out quickly before it fries your new battery.

    You did not explain why you changed out the stator a year ago, but I assume it was fried. We have seen that when either the VR or the stator goes, the other will follow shortly. Looks like your time has come.

    TQ
     
    Last edited: Aug 8, 2009
  3. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    TQ has you covered, that Voltage Regulator is bad...it is burned almost open, normally your charge voltage should not go higher than 14.5V...so the regulator should be dropping that 17.6 - 19.0 by "shunting" (parallel passing current) at an increasing rate, rather than maxing out and actually conducting less at the higher RPM.
     
  4. 2000FLSTC

    2000FLSTC New Member

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    Thanks for the info. It was a 32 amp alternator that I replaced the fried one with. I did have infinite resistance on the stator and double checked the resistance accross the pins which was .04ohms. What do you think about that along with the high AC output at high RPM's? I checked the VR pins to ground with my meter and got .08v on one pin and .19v on the other. I figured the VR was done.
     
  5. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Yep, fraid so. The fact that you are getting high voltage at your battery points to that anyway. The Vac rise as the rpms go up is expected. Mine goes up and is in the suggested range (although I have never measured it up much past about 2krpm). As long as you are getting the 1.6k-2k/1krpm, it is in spec. But both bleed back AND over voltage from the VR - done. Change it out!!

    TQ
     
  6. 2000FLSTC

    2000FLSTC New Member

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    Thanks for your time!
     
  7. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    Be careful 17V is getting up there, could start frying your TSM or ICM if allowed to continue too long.
     
  8. STEVE07

    STEVE07 Well-Known Member Staff Member Super Moderators

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    Any time the voltage gets that high it will also start boiling the acid out of your battery