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    Power usage of keyboard backlight?

    Discussion in 'HP' started by apmon, Sep 13, 2012.

  1. apmon

    apmon Newbie

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    Hello everyone,

    I was wondering what the power usage of the keyboard backlight is supposed to be?

    I have a HP pavillion dv6t-7000 with a keyboard backlight and it appears to be using 1 - 1.5W when turned on. This is "ridiculously" high, as it would correspond to about 15% of total power usage of the laptop!

    When the machine is totally idle with the backlight turned off, the machine uses about 9.5W, with it turned on it is around 11W.

    The power usage fluctuates somewhat so it is a little tricky to get exact numbers, but I have turned the light on and off several times and there is definitely a strong correlation between power usage and the keyboard light. I have also verified it both in Linux and Windows, and both OS show the same behaviour.

    Can others confirm this power usage of the backlight? Is this a defect? Is it the light itself that draws so much power? Or does it prevent some other component from going into low power mode when it is turned on?
     
    apmon, Sep 13, 2012
    #1
  2. kisetsu17

    kisetsu17 Took me long enough

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    How are you measuring all these? I swapped a backlit keyboard for my non-backlit one. I've yet to observe power draw, but I see no significant impact on battery life whatsoever.
     
    kisetsu17, Sep 13, 2012
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  3. zuvieltext

    zuvieltext Notebook Geek

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    Oh, with linux you can easily monitor the system's power consumptions through ACPI when the system is unplugged. There's a special file /sys/class/power_supply/BAT0/power_now which will give you the current mW reading. (If you think this is complicated, you can try Intel's powertop utility. There you get an overview how much power is consumed... and more importantly: what might consume it (e.g.: which device, driver, application, ...)! or what to tune to get a better battery life)

    Note: I don't know any utility for windows, but I think there's something similar.
     
    zuvieltext, Sep 14, 2012
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  4. twizller

    twizller Notebook Guru

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    Would it be possible to swap my keyboard on my hp dv6 for a backlit one?
     
    twizller, Sep 14, 2012
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  5. kamat_hp

    kamat_hp Newbie

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    It depends if your mobo supports it. There would be an extra connector which would supply additional power to illuminate the keys on back lit keyboard.



    Sent from my GT-I9100 using Tapatalk 2
     
    kamat_hp, Sep 15, 2012
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  6. Starrbuck

    Starrbuck Notebook Consultant

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    ONE WATT is too much??? Seems reasonable to me. Electricity isn't free. You're not going to be able to run extra lights without consequences.
     
    Starrbuck, Sep 15, 2012
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  7. apmon

    apmon Newbie

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    Yes, one watt is too much! If you look at a 1 Watt LED bikelight or torch, you can light up half a room with that.

    Also, if true, it would be something one should be made aware of, as it would be one of the biggest power consumers in the laptop.
     
    apmon, Sep 16, 2012
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  8. Starrbuck

    Starrbuck Notebook Consultant

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    One light vs. 80 lights is a bit different of a thing.

    How much current do lighted keyboards of other similar laptops pull? Let's do some comparisons.
     
    Starrbuck, Sep 16, 2012
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  9. kisetsu17

    kisetsu17 Took me long enough

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    In the dv6-7000 series, even if your laptop doesn't come with a backlit keyboard it still has that power connection for a backlit one. That's what I did with mine.

    IMO, 1 watt for an LED is too much. Indeed that's how much power some bike headlights use. But consider that there are a lot of LED bulbs in the keyboard. 1 watt is probably what it takes to power at least a few small LED units. The reason you can't see the intensity of 1 watt of LED light is because the lights are just seeping out of the keys and the bulbs are not really all that visible underneath.
     
    kisetsu17, Sep 19, 2012
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  10. Starrbuck

    Starrbuck Notebook Consultant

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    Exactly what I was trying to say. :)
     
    Starrbuck, Sep 20, 2012
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  11. kuskusa

    kuskusa Newbie

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    kuskusa, Nov 1, 2012
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  12. kisetsu17

    kisetsu17 Took me long enough

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    kisetsu17, Nov 2, 2012
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  13. kuskusa

    kuskusa Newbie

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    kuskusa, Nov 2, 2012
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