Usb Charger Power Consumption?

Discussion in 'Tech/Mech General' started by berni109, Jun 1, 2015.

  1. berni109

    berni109 Funster

    Joined:
    Sep 10, 2012
    Messages:
    293
    Likes Received:
    248
    Location:
    worcester
    Wired one of these cig lighter replacements to permanent live and it drawing 0.018 amp. for the led
    So in 24 hours it will use 0.432 amp or 3.042 amp every week.
    Does that sound right?
     
  2. John Laidler

    John Laidler Funster

    Joined:
    Jan 9, 2013
    Messages:
    8,564
    Likes Received:
    11,543
    Location:
    Plympton, Devon
    I guess the .018 amps is the current drawn by the led plus the current drawn on standby by the electronics inside the thing which reduce the 12v input to 5v. I suspect the light only uses a fraction of the current, the bulk will be the electronics.

    And your second figures, assuming the current reading is correct* are amp-hours and the maths look fine.

    *It is such a low current your meter may not be accurate - I doubt my cheapie screwfix one would be.
     
  3. Wildman

    Wildman Read Only Funster

    Joined:
    May 30, 2008
    Messages:
    15,458
    Likes Received:
    8,598
    Location:
    Ilfracombe, Devon
    all down to the internal resistance of the multimeter.
     
    • Like Like x 1
  4. berni109

    berni109 Funster

    Joined:
    Sep 10, 2012
    Messages:
    293
    Likes Received:
    248
    Location:
    worcester
    @Wildman is it going be in the general ball park though?
    It not a cheepy meter but obviously not top of the range.
     
    • Like Like x 1
  5. Steve

    Steve Funster Life Member

    Joined:
    May 8, 2013
    Messages:
    1,550
    Likes Received:
    1,787
    Location:
    Compton Berkshire
    looks about right, all these little bits start to add up.
    Steve
     
    • Like Like x 1
  6. Borderland

    Borderland Funster

    Joined:
    Nov 5, 2014
    Messages:
    399
    Likes Received:
    2,069
    Location:
    Borders
    From memory, 18mA (0.018 amp) sounds about right for a LED
     
    • Like Like x 1
  7. berni109

    berni109 Funster

    Joined:
    Sep 10, 2012
    Messages:
    293
    Likes Received:
    248
    Location:
    worcester
    Thanks for the responses
     
  8. pappajohn

    pappajohn Funster Life Member

    Joined:
    Aug 26, 2007
    Messages:
    29,443
    Likes Received:
    16,872
    Location:
    YO11 2BD
    Wire it to an ignition switched supply instead.
    Mine is wired to the cig lighter socket which turns off 1/2 hr after ign off or as soon as a door is opened whichever is sooner.
     
  9. Gromett

    Gromett Funster

    Joined:
    Feb 27, 2011
    Messages:
    7,905
    Likes Received:
    13,923
    Location:
    UK
    I have snipped the Leds in mine. they were disturbing me at night.
     
    • Like Like x 1
  10. Cavs

    Cavs Funster

    Joined:
    Apr 10, 2010
    Messages:
    245
    Likes Received:
    239
    Location:
    Bedfordshire
    I fitted one of these and it burnt out, I assumed because it was on all the time connected to the leisure battery. The supplier replaced it foc, and I wired the replacement with an in line switch so it's on only when being used.
     
    • Like Like x 1
  11. Reallyretired

    Reallyretired Funster

    Joined:
    Apr 27, 2008
    Messages:
    5,702
    Likes Received:
    3,207
    Location:
    Eastbourne East Sussex
    The high tech solution. I stuck a blob of blu-tac on mine, more easily reversible.
     
  12. Gromett

    Gromett Funster

    Joined:
    Feb 27, 2011
    Messages:
    7,905
    Likes Received:
    13,923
    Location:
    UK
    I tried that but as it ages (they do get warm) it eventually falls off.

    I am happy to strip things down and snip away though.... I just did the same with my USB hub which has one of these ultra bright blue LED's in. Seriously irritating at night.
     
    • Like Like x 1
Loading...

Share This Page