NIMH charge longevity?

Discussion in 'Digital Photography' started by M. Souris, Sep 10, 2003.

  1. M. Souris

    M. Souris Guest

    I gather that lithium ion batteries maintain their charge longer than
    NIMH (so I learn from this newsgroup).
    But how long will a fully charged set of NIMH AA batteries maintain
    their charge just sitting in an unused camera? Can I pick up the
    camera after a month of non-use, and expect some persisting reasonable
    battery life, if they were fully charged before insertion in the
    camera a month earlier?
    M. Souris, Sep 10, 2003
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  2. M. Souris

    JK Guest

    It depends on the temperature. At around 70F, the loss is around
    1% of the remaining power per day. At 100F, it is around 3% a day.
    So at 70F, batteries that had a complete charge would have around
    3/4 of a charge after a month, and around half their charge after
    around two months. At 100F, the batteries would only have around 40%
    of their charge after a month.
    Yes, at cool temperatures. Don't expect much power to be left after over
    a month of disuse at high temperatures.
    JK, Sep 10, 2003
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  3. M. Souris

    Bob D. Guest

    I forgot the exact numbers, but NiMHs will loose most of their charge after
    3 months. I have two sets of batteries and I periodically rotate them. That
    way my camera is always ready.
    Bob D., Sep 10, 2003
  4. M. Souris

    MJ Guest

    My experience has taught me that NiMh batteries in a camera left
    standing (or sitting) for 2 or 3 weeks will have barely a few minutes
    use left in them. If I replace them with the spares in the bag that
    have also been in there maybe 4 to 6 weeks since charged they too will
    have but a few minutes left in them, if I'm lucky. These aren't worn
    and tired old batteries that I'm talking about either. And they've all
    been 'exercised' and cycled regularly like they should be (I've grown
    up using Nicads on r/c model aircraft so I'm well practiced in this).

    Now my Canon Li-Ion - that's another story. Spare sat in bag for 5
    weeks. Thought I'd give it a top up charge before going out with
    camera. It was in the charger maybe 5 or 10 seconds before the charge
    light stopped flashing. Just love them.

    MJ, Sep 10, 2003
  5. M. Souris

    Ron Hunter Guest

    IN a month, you can expect from 70% to 80% or the original charge to
    Ron Hunter, Sep 10, 2003
  6. M. Souris

    Ron Hunter Guest

    In other words, don't leave the camera in a car in a warm climate and
    expect much charge to be left after a month. Also, in cold climates the
    available charge will be reduced, but after the batteries warm up, the
    rest of the remaining charge will be available.
    Ron Hunter, Sep 10, 2003
  7. M. Souris

    JK Guest

    Lithium AA batteries are ridiculously expensive. I can often get
    AA alkalines for around 75 cents a 4 pack. I haven't bought
    many lately, as I use mostly AA nimh batteries.
    JK, Sep 10, 2003
  8. M. Souris

    Mike Blake Guest

    It has been my experience that a NiMh cell will self discharge at a .7% to
    1.0% per day rate. At the end of a month you should expect to have about
    70% capacity remaining in the pack. As the cells get older or after they
    have been repeatedly overcharged the self discharge rate seems to increase
    some. The self discharge rate on a NiCd will be less.

    Mike Blake, Sep 10, 2003
  9. I make it a practice to recharge NiMH batteries after a month. They work OK
    in my camera up to that time. But some cameras are more demandng of the
    battery charge, so you may have to recharge more often. Do some
    experiments, and see.
    Marvin Margoshes, Sep 10, 2003
  10. M. Souris

    David Cohen Guest

    Haven't had any problems, it takes me a couple of months to run thru'
    a set of batteries. Either carry a set of spare NiMH or the special
    photographic alkalines made by panasonic and others, the're quite good
    but just use them until NiMH's are re-charged. Walmart sell a very
    inexpensive ($17) kit with a 3 hr charger/auto kit and 4 AA's. I keep
    the charger in the car, very convenient to top off or charge a set of
    AA's. Charger usually takes around 1/2 hr to top off a month's worth
    of non use then switches to trickle. Avoid topping off fully charged
    cells, the charger detects voltage change and can get confused if
    units are already fully charged resulting in some heating. Normally
    cells get warm but not hot just before fully charged.
    Dave Cohen
    David Cohen, Sep 10, 2003
  11. M. Souris

    Ron Hunter Guest

    Lithium AA cells will last about 2 times as long in a digital camera as
    AA NIMH batteries (fully charged). However, they generally cost about 4
    times as much, if not more. I keep one set of lithium as backup to the
    3 sets of NIMH batteries for my digital camera. So far, I haven't had
    to put the lithium batteries back in the camera (they came with it).
    Given that the batteries have a shelf life of 5 to 10 years, it seems
    likely that the battery will outlast the camera.
    Ron Hunter, Sep 10, 2003
  12. I never implied they should be used as regular batteries since they do
    cost so much.

    My uses for them are:
    1) To keep in the camera so it's always ready for those few snapshots I
    might take around the house. I put in NiMh batteries whenever I know I
    will be taking a lot of pictures.
    2) As a backup to the rechargable batteries in my Coolpix 5000 and D100.

    They are too expensive to be used as "regular" batteries but make great
    backup because of their very long shelf life and excellent capacity.
    Andrew McDonald, Sep 10, 2003
  13. M. Souris

    Mikey Guest

    Andrew McDonald loudly proclaimed to the world that:
    I found the Litium cells excellent for use in my Flash ( Minolta 36000 HSD)
    , they last about a year the way I use my flash so the cost isn't
    prohibitive, and they are always ready to go, so I don't have to worry about
    keeping the flash charged as well as the camera. They also are always
    available as a backup for the camera if I ever get stuck with no charged
    NiMh cells, just take them out of the flash, pop them into the camera and
    away we go ( I never had to do this, but it's my plan should the need
    Mikey, Sep 11, 2003
  14. That's a good idea. I may have to try that.
    Andrew McDonald, Sep 11, 2003
  15. M. Souris

    gr Guest

    3) They also make great batteries in very low temperatures. Lithium
    batteries don't lose as much power in sub-zero temperatures as other battery
    chemistries. Although I've never had NiMH die on me during winter, I'm sure
    the number of pictures I can take is severely reduced (unless I keep a spare
    set in a warm pocket).
    gr, Sep 11, 2003
  16. M. Souris

    JK Guest

    Perhaps there is something wrong with your batteries, or the MP3 player
    might have a mild short circuit that drains the batteries even when not
    being used? Do you use the batteries in other things? Perhaps it may
    be time to replace the batteries and charger?
    JK, Sep 11, 2003
  17. It all depends on the camera. Alkalines are notorius for sucking in
    digital cameras.
    Andrew McDonald, Sep 11, 2003
  18. M. Souris

    Ron Hunter Guest

    Replace them. They are damaged.
    Ron Hunter, Sep 11, 2003
  19. How old are those NiMH cells? I haven't seen 1200 mAh cells in a long
    time. Perhaps they're just at the end of their life.

    As for the MP3 player, there are many electronic devices that don't have
    a true "off" switch. The electronics goes into a sleep mode, so it can
    be awakened by a press on the "on" button, but it continues to draw some
    current while it is "off". This will exhaust the batteries eventually
    even when the device is left "off". The manufacturer expects you'll use
    the device often enough that the off-state current will not matter.

    Dave Martindale, Sep 11, 2003
  20. Thanks for the response.

    I've also used them in a pocket TV, powered toothbrush, and a Discman.

    And the MP3 player is an off-brand (Yo!MP3 by Kaser Corporation), so you may
    be right about the draining issue. I do know they did redesign it and sell
    it as Yo!Fun.

    I'm really not seeing any significantly longer life vs. alkaline
    batteries... *except* when I use them in a digital camera. Even then--for
    some cameras, the batteries are apparently too low to use the LCD preview
    after a while, but using the viewfinder is still okay for about 20 or more
    shots that even use the flash.

    I've got two sets, bought about about six months apart... so one set is
    green labelled and the other set is blue labelled.

    The charger came with the first set of batteries, so it's an Energizer
    5-hour charger, if that helps any. It sort of shuts itself off after 5-hours
    and then has to be unplugged and plugged back in to start charging again.
    Maybe it's not fully charging the batteries?

    Daniel W. Rouse Jr., Sep 11, 2003
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