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  • Low voltage reading.

    Hello,

    i measured voltage from battery and reading 13.5v. All things on and reading 12,8v. I measured directly from alternator and 13,6v.
    Alternator now new and still same issue.
    What it can be? Bad ground?

  • #2
    Are you getting a warning light??
    belt tight enough etc..

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    • #3
      Originally posted by Monkeymagic View Post
      Are you getting a warning light??
      belt tight enough etc..
      At beginning there is warning light. Little gas and warning light goes off and thats it. Belt is tight.

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      • #4
        that is normally an indication of a poor voltage regulator, although you say you have replaced the alternator. A healthy alternator should give between 13.5 to 14.5 volts with all consumers turned off.
        Why did you replace the old one???

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        • #5
          Under load if you have 13.6 at the alternator output terminal and only 12.8 at the battery then you have resistance somewhere in the circuit?.....either in the feed or earth circuit. You can use your voltmeter to find where?

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          • #6
            Originally posted by John. View Post
            Under load if you have 13.6 at the alternator output terminal and only 12.8 at the battery then you have resistance somewhere in the circuit?.....either in the feed or earth circuit. You can use your voltmeter to find where?
            13,5 from alternator is also little low as i have 14,4 regulator. Alternator have 2 wire. One + and one for signal. Signal wire only send signal so it cant be issue. Alternator takes ground from engine but how i can be sure that engine ground is good?

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            • #7
              Originally posted by ristokru View Post
              ….. how i can be sure that engine ground is good?
              Under load (lights, heater ,etc on), put your voltmeter between the alternator casing and battery neg...….this will give you the volts drop on the earth circuit, it should be as low as possible, move the (voltmeter) leads between different points to pinpoint where the problem (resistance) is.

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              • #8
                Originally posted by John. View Post

                Under load (lights, heater ,etc on), put your voltmeter between the alternator casing and battery neg...….this will give you the volts drop on the earth circuit, it should be as low as possible, move the (voltmeter) leads between different points to pinpoint where the problem (resistance) is.
                I have battery in trunk, so cant use multimeter like that. Can I test ground like that, + to alternator and minus from car chassis?

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                • #9
                  Originally posted by ristokru View Post

                  I have battery in trunk, so cant use multimeter like that. Can I test ground like that, + to alternator and minus from car chassis?
                  Yes, and then do chassis to battery neg, add the two together and you'll have total earth circuit drop. It sounds like you have an understanding of what I'm trying to describe but there maybe a "you tube" video which would "show" better?

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