How many mA, peak, do digital cameras draw from Photo Lithium batteries?

Discussion in 'Digital Photography' started by Guest, Jan 3, 2005.

  1. Guest

    Guest Guest

    Anybody ever measure what cameras, including cameras with LCD screens,
    draw from 223, CR-V3, or CCR-P2 photo lithiums?

    Also, is there a reason why camera manufacturers use different sizes
    of these lithium batteries?

    Also, if the battery specification states "10 mA" draw, why is it that
    (allegedly) some cameras draw 1,000 mA from the battery?

    Thanks for all replies.
     
    Guest, Jan 3, 2005
    #1
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  2. Guest

    Al Dykes Guest


    The full specs are a set of graphs for a range of current and time.
    Look at the make and model on your lithium cell and google for
    specifications.

    The camera has peak current requirements when taking a shot with
    flash, a medium demand for a shot w/o flash, and an idle current when
    on but sleeping. One amp when recharghing the flash and writing the
    prior shot to the CF card doesn't seems unreasonable.
     
    Al Dykes, Jan 3, 2005
    #2
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  3. Guest

    Harvey Guest

    1,000 mA draw is not unreasonable. Camera engineers will work with battery
    engineers to use whatever batteries will fit the application and be
    available in general commerce. Each manufacturer will use what best fits
    his particular application. the 10 mA draw is one test method for
    batteries. Roughly speaking a 2,000 mAh rated battery will last 200 hours
    with a 10 mA load. The same battery would last 2 hours with a 1,000 mA
    load. The most common test charging current and test load current for
    batteries is C/10 that is for a 2,000 mAh battery it would be 200 mA.
     
    Harvey, Jan 3, 2005
    #3
  4. Guest

    Henry Law Guest

    I Googled extensively but found only details of the capacity of the
    *battery*, not the current demand from the *camera*.

    I posted on rec.photo.digital.slr-systems on a similar topic earlier
    today; decided not to cross-post to here ;-) I'm wondering whether
    one could build an AC adapter and what current it would have to
    supply; also what the "B" anbd "D" terminals do.
     
    Henry Law, Jan 3, 2005
    #4
  5. The camera only draws high currents when it's busy doing something like
    encoding a JPEG, manipulating the sensor data, driving the LCD, or
    charging the flash. Peaks over 1 Amp are common. Idle currents of 1mA
    are typical too.

    Each battery has a rate at which its chemical reaction can take place.
    Attempting to exceed that rate causes the voltage to drop and the
    battery to generate heat. A camera can momentarily draw high currents
    as long as there's a rest period for the battery to catch up. Some
    cameras, like the Oly C series, will turn on fewer components of the
    camera at once if it detects the battery voltage sagging.

    Alkaline batteries are quite slow, which is why cameras tend to suddenly
    power off while using them. NiCd is the fastest, some being able to
    dump most of their power in under one minute. Newer NiMH batteries can
    handle 30 minute discharge rates efficiently enough but they're better
    at 2-4 hour rates. Lithium batteries vary enormously depending on make
    and chemistry. I don't know what it is for camera batteries because I
    haven't seen specifications posted.
     
    Kevin McMurtrie, Jan 3, 2005
    #5
  6. This was posted to this group a while back:

    -------- Original Message --------
    Subject: Canon 10D power consumption
    Date: 12 Nov 2004 10:09:48 -0800
    From:
    Newsgroups: rec.photo.digital

    (Tried to post this yesterday. It's not in google, so once again...)

    Here are some current measurements of a Canon 10D. The power supply
    was a single, full-charge, 3rd party BP-511, 8.2V. Various
    operations:

    off 0mA (probably something in the microamp area)

    idle 98mA

    active 406mA (shutter half-press; exposuring ongoing)
    388mA (no shutter button contact)
    421mA IS only \
    672mA IS + AF > shutter half-pressed
    665mA AF only /

    AF measurements are "peak".

    imaging 1150mA (peak - _very_ brief)

    editing 250mA/315mA \ LCD bright
    233mA |
    214mA >
    195mA |
    186mA/250mA / LCD dim

    writing 150mA (with bursts of 220mA)

    bulb 345mA (holding the shutter open in 'bulb' exposure)

    The lens was an EF 500/4, but others (EF 20/2.8, EF 300/4) didn't
    change much. Note the relatively low impact of using IS, and the
    large impact of the AFing (the lens was racking from close to
    infinity). Also note the low image write current.

    Peak current of 1.15A was measured during a 9 "raw" frame pipeline
    fill/drain episode. This peak was unaffected by IS or AF, suggesting
    that it is still an underestimate (unlikely given the Fluke meter I
    was using), or that AF (the larger of the two) is briefly disabled
    during mirro flip, shutter open, etc. Note that the act of taking a
    picture should demand a fair amount of energy given how fast these
    moving parts are moving.
     
    Roger N. Clark (change username to rnclark), Jan 4, 2005
    #6
  7. Guest

    Frank ess Guest

    Very interesting.

    Do you suppose Canon pays any attention to these? Would the functions
    have been optimised to minimize energy use, or just developed and the
    draw falls where it may? Is it likely any significant changes would be
    apparent in the presumably "improved" 20D?

    I suppose one could "port, polish, airflow, balance", and otherwise
    blueprint the mechanics of a camera.
     
    Frank ess, Jan 4, 2005
    #7
  8. Since battery life is an issue, I bet they have improved these
    numbers on newer cameras, but then they process data faster,
    so it may be a wash.

    Roger
     
    Roger N. Clark (change username to rnclark), Jan 5, 2005
    #8
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