Dimming headlight

Discussion in 'GS Boxers' started by Yousef, Nov 13, 2012.

  1. Yousef

    Yousef n00b

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    I've been noticing my headlight would dim at a stop light but when I rev the engine a little it gets brighter. It also does it when I have my heated gear on. The Gerbings thermostat will blink since I have it turned down and my headlight will dim every time the thermostat blinks.

    I'm about to install my DDM HID kit and not sure how it will deal with this.

    I'm thinking my battery is the cause but I could be wrong.

    Any ideas? :ear
    #1
  2. Karlxx

    Karlxx Dirt Curious

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    This is normal behaviour as the alternator is not able to produce as many watts at Idle speed. A tired battery will make this worse.

    A HID will not fire up at all at low voltage, but once its going they tend to work OK at Idle.

    K
    #2
  3. def

    def Ginger th wonder dog

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    That should be amps.
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  4. JimVonBaden

    JimVonBaden "Cool" Aid!

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    Doesn't amps = watts/volts? So, in effect the statement is still accurate? :dunno

    Jim :brow
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  5. GS Addict

    GS Addict Pepperfool

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    The term Watts covers it better as the voltage droops as well at low rpm.
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  6. def

    def Ginger th wonder dog

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    So, you're gonna argue with an engineer? (my wife does all the time).

    The Watt is a unit of work.

    The volt is the force or EMF and the ampere is the unit of electrical current.

    When the load consumes more current than the system is delivering (alternator), the battery supplies the difference. When this happens in the typical automotive electrical system, the voltage is reduced unless the alternator delivers more current (amperes) to offset the loss.

    So, when the lights dim, it is due to more current (amperes) being called for than is being delivered.

    :deal
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  7. GS Addict

    GS Addict Pepperfool

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    Don't start with the Engineer stuff. I work with them all the time. I am a certified Industrial Electrician.
    Pissing contests achieve nothing.

    The only way current will flow out of the alternator is if its output voltage is higher than the battery voltage.
    So the term watts is not incorrect
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  8. def

    def Ginger th wonder dog

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    Not incorrect. Now your English is in question as well as your electrical knowledge.

    Watts don't flow anywhere....current does.

    And this is no contest...however, it is useful to use correct terminology and references when attempting to cite fact. That's how we learn, communicate and pass knowledge.

    I understand the relationship between watts, volts and current. Also, our alternators are rated in both watts and amperes. However, in an automotive electrical system, the voltage is usually considered to be constant (and regulated electronically in the alternator) with load and current being the variable.

    Remember also, current is the measure of coulombs, which are ampere seconds, or the measure of how many electrons flow in the circuit.
    #8
  9. Thunder Pig

    Thunder Pig Been here awhile

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    How about just say demand exceeds supply and then the lights dim.:evil
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  10. GS Addict

    GS Addict Pepperfool

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    In the end it's either the the battery or the alternator doing the work depending on RPM.

    Work = HP = Watts

    I am not arguing anymore, and stop with the insults about my knowledge.
    #10
  11. jings

    jings Been here awhile

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    :rofl:rofl:rofl
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  12. def

    def Ginger th wonder dog

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    As usual, the pig get's it.
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  13. Yousef

    Yousef n00b

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    Dang! What happened? :yikes

    Ok, I'll install a new battery and see if it helps.
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  14. RFK

    RFK Been here awhile

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    Generators are measured in wattage not amperage. The voltage can vary which will vary the amperage so wattage is a better term to use... it is constant.
    #14
  15. picinisco

    picinisco Scottish Transplant

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    No idea what the 1965 riots in LA has to do with anything.
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  16. Karlxx

    Karlxx Dirt Curious

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    Wow, just trying to help here... I am also an engineer, albeit mechanical. I believe we are both correct, I just used watts in my description because I thought power output would be more easy to understand.
    #16
  17. GS Addict

    GS Addict Pepperfool

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    My point precisely, thank you
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  18. MotorradMike

    MotorradMike MIL-TFD-41

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    Pissing contests are fun, no?

    I say it's voltage that drops. :D

    C'mon guys, voltage, current, and power are all down at low RPM.
    #18
  19. def

    def Ginger th wonder dog

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    Sorry. You're likely smarter than I.
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  20. LaurelPerryOnLand

    LaurelPerryOnLand Long timer

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    Bueller...Bueller...Rodney King...Rodney King!:huh
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