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Thread: cranking issue solved?

  1. #31
    Variable Bitrate HybridFox's Avatar
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    ooo ok
    soo technically i was sorta right

  2. #32
    Variable Bitrate Dracos's Avatar
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    yea, but what has been designed does what you said without that switch. it just does it all automatically.

    Farad caps are dangerous and should be treated as such. they only provide a couple of miliseconds shot of power for something like a bass hit. it wont work for the time it takes to start.

    And yes - cranking = turning your engine over to start.

  3. #33
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    The isolator works well, we use it in car stereo/alarms quite often..my simple question is this, will the 2nd battery see a voltage spike with starting the car? The setup would work perect for me (using a regular tower PC and 12" flat monitor like a home PC) but dont want to fry my computer when its started. Figgere a sealed battery will allow the computer to go into hybernate and keep it going for a while and not drain it, then upon needing the comp again I can hit the keyboard space bar (yes usung a keyboard, its needed in my system needs) or can wire a momentary push button to power it back up. But again the power spike makes me nervous!

  4. #34
    Variable Bitrate Dracos's Avatar
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    nope, the second battery will see NO change in voltage during crank. I dont know where you got the idea for that

  5. #35
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    i have tested the diode theory and it works pefectly. I needed to add a heatsink as it was reaching 90'C during running. The second battery charges OK, and a minute or two of car running provides enough power to my 3a/h battery powering my PC for 15 seconds. Afterall, thats all that the battery is used for.

    Once again, I may be wrong in my judgements, but it works for me.

  6. #36
    Variable Bitrate Dracos's Avatar
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    yep. thats it.

    good job on the test.

  7. #37
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    Heh

    Nobody's mentioned this yet but I'll go into it.

    the reason relays and switches (even manual ones) aren't very good for this application is arcing.

    If you have a switch- for a few milliseconds as you disconnect the switch, you will have a few microns wide patch of air in the circuit, between switch contacts.
    This is equivalent to adding resistance, and as soon as you have resistance and voltage, you have current and watts- so basically you can get a big ZAP between the two batteries with a relay in place.
    I can't claim full credit for the isolator idea- after all I just sort of searched on the net for it, but I can claim full credit for the bad idea- relays! lol

    college automotive class teachers and the internet are wonderful things.

  8. #38
    Variable Bitrate Dracos's Avatar
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    This is the man that gave me a hand with the circuit idea (as in my previous plug)

  9. #39
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    Thumbs down Isolator??? :S

    Hi:

    If the isolator are two diodes, one for each battery, the diode working for the car batt is not needed, and that power will be wasted(heat) without any reason.

    Why are you going to mess with:
    -Your altenator(disconecting it)
    -Your car battery (putting the isolator)
    -An expensive device (the isolator, comparating to 1 diode)
    -And your system batt,

    if you can mess just with:

    -Your system batt
    -A cheap device (less than 2$US)

    and obtain the same results?

    I left the question in the air. I just dont understand why complicate life.



    Quote Originally Posted by Mr Crown
    The diode will not waste power when you stop your engine. It will just get a little hot when recharging the PSU Battery (maybe some heat sink needed). It wont lower the full charge voltage of the PSU battery.
    Quote Originally Posted by Gavroche
    i have tested the diode theory and it works pefectly. I needed to add a heatsink as it was reaching 90'C during running. The second battery charges OK, and a minute or two of car running provides enough power to my 3a/h battery powering my PC for 15 seconds. Afterall, thats all that the battery is used for.

    Once again, I may be wrong in my judgements, but it works for me.

  10. #40
    FLAC
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    Has anyone successfully done this with any other systems than the low power VIA M/bs? I want to build a tank circuit for an AMD mAtx board where the current draw could be as high as 16A.
    Progress: 80% - Permanent install left.
    Motion LS800 Tablet PC and dock.
    Vista, Bu-535 GPS, RoadRunner, MPT2006.

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