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Thread: Power consumption of laptop on standby

  1. #1
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    Power consumption of laptop on standby

    I have just received my in car charger from laptopshop.co.uk, very impressed shipped within a day and only 50. And i just tested it in the cigarette lighter and it actually works, all good.

    The question i have when hard wiring the charger, do i wire it up so that it comes on ignition or stays on permanently, i guess i dont know how much power the thing will consume when running in standby? Will say in 5 days will it have flattened my battery?

    The other question, is which wire will be which on the charger, i havent split it yet, but will it be obvious which is positive and which is negative?

    Thank you all for your support getting there, my lcd will be here soon from armen Cant wait.

  2. #2
    jol
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    Re: Power consumption of laptop on standby

    If you got a voltmeter that handles bout 5 amps you could split the wire, go into standby, and remove the middle wire, then connect the meter, see pic. this is to not break the meter if it cant handle non-standby power consumtion.

    the peg in the middle is plus, and the contacts on the sides are neg.


  3. #3
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    Jol good thought, but unnecessary. Laptop power supplies tend to stay under 4-5A maximum, they just pump up the voltage when they need more power. Most ammeters can handle up to 10A of current, so you should just be able to run it directly, and that way see how much power your computer takes while both running and in standby.

    I have a dell inspiron 8100 laptop with 512MB, and I can get about a week on standby from a single lithium-ion battery. You can probably get closer to about 2 weeks from your car battery, but I wouldn't think much more than that.

    Just to clarify, when hooking up an ammeter you have to hook it up in series with the circuit (i.e. inline), so you'd have to splice into either the +ve or -ve line (either one doesn't matter) and just connect the ammeter directly in to the spliced line.

    However this entire thread is rather academic because car batteries are designed to provide high-current for short periods of time, they are really inefficient at providing a trickle current, so you won't get anywhere near the actual maximum amount of power that the battery can hold.
    IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.

  4. #4
    jol
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    k mine got like 2 or something.

  5. #5
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    got like 2 what?
    IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.

  6. #6
    jol
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    amps

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    Ah OK.. My Inspiron 8100 is 20V 3.5A, and the 8200 series is 4A at 20V. I've even seen some 24V 4A power bricks, but I haven't seen higher than that (yet). It's much easier and cheaper to up the voltage to get more wattage than it is to provide more current.
    IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.

  8. #8
    jol
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    I was talking about the amp-meter..

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