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Thread: cranking issue solved?

  1. #11
    FLAC
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    Sep 2004
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    Of course! If you hook up the PC and battery to the *switched* 12V, then you are safe from over voltage (at least in my car since it switches off during the crank). However, you are forced to hibernate the pc (preferably automatically) at ignition off. But an additional plus is your PC can't drain your main battery!

    Overall, I think I vastly prefer this approach. I was going to go with hibernate anyway.

  2. #12
    FLAC
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    Sep 2004
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    And I read somewhere that some systems only use 7mA in standby. So it would last a long time off just the 7.2*Ah battery (43 days!). So standby is potentially still viable.

  3. #13
    FLAC
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    And no diodes are harmed (required) in the making of this solution.

  4. #14
    Newbie
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    Oct 2004
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    Yes it will drain energy from your car batt.

    HEY BEWARE

    Of course this setup will drain power from you car batt. It just dont allow energy from the sys batt to the car batt or car electonics connected to it. So, when you crank, the sys batt just supply the system, but when you stop cranking, your sys batt and audio system drain energy from the auto gen/batt circuit. When you stop your engine, it will continue draining from car batt, but as no generation is present your sys batt also will discharge, so both supply when engine's stopped.

  5. #15
    FLAC
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    Not with the switched 12v. The pc battery would be physically disconnected from the main car battery when the car is switched off. That's the beauty of it.

  6. #16
    Newbie
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    Oct 2004
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    Arrow You dont need a switch to solve crank problem

    The diode in this case is an "auto" switch. If you let your system running on your sys batt, then your sys batt should be bigger. This case is just to solve the crank problem, not to last long time.

    The switch is a good option cause your systems are isolated (car and audio system), but if so, your sys batt should be bigger.

  7. #17
    FLAC
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    But, I do need to confirm this really avoids spikes post crank. It may not.

  8. #18
    Newbie
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    Oct 2004
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    Exclamation No it wont protect your system from over voltage.

    But you should resolve that problem (is not normal). Do you know what a freewheel diode is??

    Here it goes: (simplified diagram)



    If a work shop cant help you, this is a cheap yet working solution.

    The diodes feeds the alternator with its own over voltage, until it falls and dissapears.

    Hope help.

  9. #19
    Low Bitrate
    Join Date
    Jan 2004
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    With your original (diode) circuit, is there not a voltage drom, roughly 0.5V due to the diode? Thus menaing the sys-batt doesn't get the full charging voltage and is never fully charged?

  10. #20
    Variable Bitrate Dracos's Avatar
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    Sep 2004
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    Talking

    ok, so after a little talk with a knowledgeable friend, im moving away from relays and diodes. I am proposing to use an isolator. the diagram will explain. Many props to my friend skaal-tel from modthebox forums for his input.
    Attached Images Attached Images  

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