Alternator charging up to 17 volt with regulator OK (?) | FerrariChat
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Alternator charging up to 17 volt with regulator OK (?)

Discussion in '206/246' started by chritin, Dec 22, 2021.

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  1. chritin

    chritin Rookie

    Jul 12, 2007
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    france
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    chritin regis
    #1 chritin, Dec 22, 2021
    Hello to all,

    I measured today the voltage on the batterie during charging with engine on, and reach 17V at 3000 rpm. I've 2 regulators, the original one and a new electronic one, and in the two cases I measured above 14 volts.

    I precise that the 8A fuse on the excitation return file in the engine compartment is OK.
    And the ammeter goes full scale at 40A when I accelerate (the nuts are tight at the rear of the ammeter)

    Any idea what I could check to solve this problem ?

    Thanks

    Régis
     
  2. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Cowboy Capitol of the World
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    Brian Crall
    #2 Rifledriver, Dec 22, 2021
    Thats the regulators job.
     
  3. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    4,191
    Norfolk - UK
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    Tony
    #3 TonyL, Dec 22, 2021
    Regis
    In a nutshell, NO it isnt correct.

    I had a similar problem to you a few years ago and although its a simple charging circuit there are many items that can go wrong, most are to do with poor wiring connections especially the firewall fuses, ammeter connections and earthing at the VR. If the large red wire from the firewall fuse block is getting hot you need to find the problem and fast. It will destroy your loom.

    Any high resistances in the circuit will give you major problems.

    Read this thread, I ended up renewing the large red cables and problem was solved.

    https://www.ferrarichat.com/forum/search/117810552/?q=charging+problems&t=post&o=relevance

    Tony
     
  4. DinoLasse

    DinoLasse Formula Junior
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    May 26, 2009
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    Lars
    #4 DinoLasse, Dec 22, 2021
    Last edited: Dec 22, 2021
    17V is always wrong, will eventually damage the battery, if nothing else. Above 14V is pefectly OK. 13.6V to 14.3V is ideal, but up to 14.5V would be fine.

    I do not understand the second sentence in your post. Are you saying that the original regulator gives 17V and the new electronic one gives over 14V? If so, the new one is good.

    If both regulators give the same output of around 17V, you have to look at problems with the wiring and connections. One possibility is a short circuit to ground in the field winding (excitation) return lead. That would cause the alternator output to go to maximum. Other possibilities are bad ground connection to the regulator. That would make the voltage sensing relay not "see" the higher voltage. Etc., etc.
     
  5. chritin

    chritin Rookie

    Jul 12, 2007
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    france
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    chritin regis
    #5 chritin, Dec 23, 2021
    Thanks a lot for your answers, I will check all these points soon

    I hope I won't need to change the alternator because dismantling it is a nightmare !

    Regis
     
  6. chritin

    chritin Rookie

    Jul 12, 2007
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    france
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    chritin regis
    #6 chritin, Dec 23, 2021
    (And the two regulators give the same result, about 17V, so it's not the regulator itself the problem)
     
  7. DinoLasse

    DinoLasse Formula Junior
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    Lars
    #7 DinoLasse, Dec 23, 2021
    Yes, changing the alternator is no fun, apparently. But I don't think you will need to.
    You can verify that the alternator (and battery) are functioning correctly by this simple test: Connect a high powered light bulb across the battery with test leads. I usually use an old headlight bulb or two. At least 50 - 60W, but higher is better. With ignition key off, measure the voltage across the battery under this load. If it is at least 11.6V or so, the battery is OK. Then start the engine. As you slowly increase the rpm, the lamp should light brighter and the voltage should rise to close to 14V. If it does, your alternator is good, and you can relax and concentrate on the regulator and wiring instead.

    If the voltage continues to rise to 17V at higher rpm under this load and the bulb becomes super bright, it still means your alternator is good, but the regulator is not functioning. Measuring the voltage at the input and output of the regulator should give you an indication of what is happening. Good luck with the trouble-shooting!
     

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