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Discuss using bulbs with different current in the alt.auto.mercedes forum at Car Dealer Forums; If I replace my 6w sidelights with longer life LED bulbs taking a few milliamps, ...
  1. #1
    Nihil
    Guest

    Default using bulbs with different current

    If I replace my 6w sidelights with longer life LED bulbs taking a few
    milliamps, presumably the ship-board computer will think the bulbs have
    blown and will continue to annoy me by saying so every time I turn them on.

    Is there a way to tell the computer to expect low current drain from the
    sidelights and not flag an error?

    year 2000 E320 cdi



    › See More: using bulbs with different current

  2. #2
    macdrone
    Guest

    Default Re: using bulbs with different current


    Nihil wrote:
    > If I replace my 6w sidelights with longer life LED bulbs taking a few
    > milliamps, presumably the ship-board computer will think the bulbs have
    > blown and will continue to annoy me by saying so every time I turn them on.
    >
    > Is there a way to tell the computer to expect low current drain from the
    > sidelights and not flag an error?
    >
    > year 2000 E320 cdi


    Yes, put an inline resistor of the difference and that will make the
    Headlight relay believe the normal bulb is in there. If the LED's fail
    it will still show a drop and the light will come on.


  3. #3
    Alec
    Guest

    Default Re: using bulbs with different current

    The normal bulb takes about 0.5 Amp And the LED probably 0.05 Amp
    So the resistor in parallel with the led must take about 0.45 Amp to appear
    normal, say 27ohm, and dissipate about 6 Watts.it may get as hot as a bulb.

    If the LED fails, assuming it goes open circuit, the current will change by
    0.05Amp and I doubt the computer will detect this.

    I also doubt that Mercedes have the possible use of LED's programmed into
    the current range of cars yet.

    But it will come soon, probably with a model change and possibly with the
    change to 42Volts which has often been suggested.

    Alec




    "macdrone" <macdrone@hotmail.com> wrote in message
    news:1164633552.818965.85250@45g2000cws.googlegrou ps.com...
    >
    > Nihil wrote:
    >> If I replace my 6w sidelights with longer life LED bulbs taking a few
    >> milliamps, presumably the ship-board computer will think the bulbs have
    >> blown and will continue to annoy me by saying so every time I turn them
    >> on.
    >>
    >> Is there a way to tell the computer to expect low current drain from the
    >> sidelights and not flag an error?
    >>
    >> year 2000 E320 cdi

    >
    > Yes, put an inline resistor of the difference and that will make the
    > Headlight relay believe the normal bulb is in there. If the LED's fail
    > it will still show a drop and the light will come on.
    >




  4. #4
    gw
    Guest

    Default Re: using bulbs with different current

    > So the resistor in parallel with the led must take about 0.45 Amp to appear

    You meant to say in Series right?

    gamini


  5. #5
    Alec
    Guest

    Default Re: using bulbs with different current

    No

    There will be a resistor in series with the LED but if it is a 12V LED it
    will be inside the LED. If it is not a 12V LED the you will have to add a
    resistor to limit the LED current.

    I was referring to a resistor in parallel with the LED (or LED with series
    resistor) which is added to deceive the car computer into thinking that a
    normal bulb is fitted.

    Alec
    "gw" <wgamini@gmail.com> wrote in message
    news:1164689513.275672.259670@l39g2000cwd.googlegr oups.com...
    >> So the resistor in parallel with the led must take about 0.45 Amp to
    >> appear

    >
    > You meant to say in Series right?
    >
    > gamini
    >




  6. #6
    Nihil
    Guest

    Default Re: using bulbs with different current

    Alec wrote:
    > No
    >
    > There will be a resistor in series with the LED but if it is a 12V LED it
    > will be inside the LED. If it is not a 12V LED the you will have to add a
    > resistor to limit the LED current.
    >
    > I was referring to a resistor in parallel with the LED (or LED with series
    > resistor) which is added to deceive the car computer into thinking that a
    > normal bulb is fitted.
    >
    > Alec
    > "gw" <wgamini@gmail.com> wrote in message
    > news:1164689513.275672.259670@l39g2000cwd.googlegr oups.com...
    >>> So the resistor in parallel with the led must take about 0.45 Amp to
    >>> appear

    >> You meant to say in Series right?
    >>
    >> gamini
    >>

    >
    >

    Thanks to all from the originator of this post. I understand that a
    resistor in parallel to shunt 0.5 amp would fool the computer into
    thinking there would be a normal bulb there. And, yes, there will be
    another resistor insider the LED, but this is not my concern.

    The trouble with this is that

    1 an external parallel resistor would be difficult to install on the
    wiring loom,
    2 there would be no warning of a bulb failure, though LEDs last a long time.

    I had thought that I read in a thread on Xenon headlight bulbs that it
    was possible to tell the computer to use different limits of acceptable
    current. Is this really not possible?


  7. #7
    Alec
    Guest

    Default Re: using bulbs with different current

    Sorry I do not have any info on the capabilities or reprogramability of the
    in car computer.

    Alec
    "Nihil" <SpamNihil@blueyonder.co.uk> wrote in message
    news:q6%ah.8367$k74.1893@text.news.blueyonder.co.u k...
    > Alec wrote:
    >> No
    >>
    >> There will be a resistor in series with the LED but if it is a 12V LED it
    >> will be inside the LED. If it is not a 12V LED the you will have to add a
    >> resistor to limit the LED current.
    >>
    >> I was referring to a resistor in parallel with the LED (or LED with
    >> series
    >> resistor) which is added to deceive the car computer into thinking that a
    >> normal bulb is fitted.
    >>
    >> Alec
    >> "gw" <wgamini@gmail.com> wrote in message
    >> news:1164689513.275672.259670@l39g2000cwd.googlegr oups.com...
    >>>> So the resistor in parallel with the led must take about 0.45 Amp to
    >>>> appear
    >>> You meant to say in Series right?
    >>>
    >>> gamini
    >>>

    >>
    >>

    > Thanks to all from the originator of this post. I understand that a
    > resistor in parallel to shunt 0.5 amp would fool the computer into
    > thinking there would be a normal bulb there. And, yes, there will be
    > another resistor insider the LED, but this is not my concern.
    >
    > The trouble with this is that
    >
    > 1 an external parallel resistor would be difficult to install on the
    > wiring loom,
    > 2 there would be no warning of a bulb failure, though LEDs last a long
    > time.
    >
    > I had thought that I read in a thread on Xenon headlight bulbs that it
    > was possible to tell the computer to use different limits of acceptable
    > current. Is this really not possible?
    >




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