Discharging rechargable batteries

Discussion in 'Digital Photography' started by tngtest@attglobal.net, Mar 16, 2005.

  1. Guest

    I have a digital camera (Canon Powershot A85) and I am interested in
    how to more fully discharge the NiMH 2300 mAh AA batteries I use.
    Although I have read that this type of battery is less susceptible to
    "memory" problems, I have noticed that even though the camera indicates
    that the batteries need to be charged, my battery tester still shows
    them at the lower end of the lower end of the good/green range instead
    of yellow or red. Is this normal, or is there a way to more fully
    discharge them?
     
    , Mar 16, 2005
    #1
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  2. Ron Krebs Guest

    <> wrote in message
    news:...
    > I have a digital camera (Canon Powershot A85) and I am interested in
    > how to more fully discharge the NiMH 2300 mAh AA batteries I use.
    > Although I have read that this type of battery is less susceptible to
    > "memory" problems, I have noticed that even though the camera indicates
    > that the batteries need to be charged, my battery tester still shows
    > them at the lower end of the lower end of the good/green range instead
    > of yellow or red. Is this normal, or is there a way to more fully
    > discharge them?
    >


    See if there's a battery discharge option in the setup menu on your camera.
    Mine has one.

    Ron
     
    Ron Krebs, Mar 16, 2005
    #2
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  3. Gene Guest

    Look on the bottom of your AA NiMH batteries,
    if you do not see the letters stamped, "HR"
    Then you may want to purchase a few Energizer
    2500 mAh at Sam's, etc.

    IMHO, the 2500mAh and the "HR" are very important :)

    I have tried discharging NiMH AAs, without success.
    In fact, I believe that it hurts the cause to power cycle them



    <> wrote in message
    news:...
    >I have a digital camera (Canon Powershot A85) and I am interested in
    > how to more fully discharge the NiMH 2300 mAh AA batteries I use.
    > Although I have read that this type of battery is less susceptible to
    > "memory" problems, I have noticed that even though the camera indicates
    > that the batteries need to be charged, my battery tester still shows
    > them at the lower end of the lower end of the good/green range instead
    > of yellow or red. Is this normal, or is there a way to more fully
    > discharge them?
    >
     
    Gene, Mar 16, 2005
    #3
  4. Ron Guest

    There are chargers that will do it for you (do a little Googling). I
    simply put mine in my MP3 player, which will take them a lot lower than
    my cameras before giving up. I believe CD players and radios are just
    fine for that as well. Don't use a flashlight --- it'll take 'em too low
    trying to drain every last bit of energy from them. My sense is that a
    'full' discharge may be good now and then as long as it isn't too full,
    but it really isn't terribly necessary once the batteries are broken in
    and you let your camera do its thing. Happy to be corrected and I'm
    sure I will be if I'm wrong on that!

    wrote:
    > I have a digital camera (Canon Powershot A85) and I am interested in
    > how to more fully discharge the NiMH 2300 mAh AA batteries I use.
    > Although I have read that this type of battery is less susceptible to
    > "memory" problems, I have noticed that even though the camera indicates
    > that the batteries need to be charged, my battery tester still shows
    > them at the lower end of the lower end of the good/green range instead
    > of yellow or red. Is this normal, or is there a way to more fully
    > discharge them?
    >
     
    Ron, Mar 16, 2005
    #4
  5. wilt Guest

    Maybe your battery tester is designed only to test alkalines, which
    start at 1.5v and progressively drop voltage until about exhausted at
    1.2v. In comparison NiMH start at about 1.3v and slowly drop in
    voltage until exhausted. So starting at 1.3v it goes to the low end of
    alkaline voltage!
     
    wilt, Mar 16, 2005
    #5
  6. Martin Guest

    <> wrote in message
    news:...
    > I have a digital camera (Canon Powershot A85) and I am interested in
    > how to more fully discharge the NiMH 2300 mAh AA batteries I use.
    > Although I have read that this type of battery is less susceptible to
    > "memory" problems, I have noticed that even though the camera indicates
    > that the batteries need to be charged, my battery tester still shows
    > them at the lower end of the lower end of the good/green range instead
    > of yellow or red. Is this normal, or is there a way to more fully
    > discharge them?
    >


    There are chargers that put the batteries through a "conditioning" cycle
    before recharging them. This appears to be a controlled discharge step that
    they say is only needed for the initial recharge and only occasionally
    thereafter. I have one, a Maha c204, that gives me the longest working time
    I've been able to get from NiMH AAs. They say that their later models will
    revive "dead" NiMHs.
     
    Martin, Mar 16, 2005
    #6
  7. Bob Salomon Guest

    In article <>,
    wrote:

    > I have a digital camera (Canon Powershot A85) and I am interested in
    > how to more fully discharge the NiMH 2300 mAh AA batteries I use.
    > Although I have read that this type of battery is less susceptible to
    > "memory" problems, I have noticed that even though the camera indicates
    > that the batteries need to be charged, my battery tester still shows
    > them at the lower end of the lower end of the good/green range instead
    > of yellow or red. Is this normal, or is there a way to more fully
    > discharge them?


    Tge Ansmann Powerline 4 and Powerline 6 chargfers have a manual
    discharge feature. The Ansmann Energy 8 and Energy 16 have an automatic
    refreash cycle which automatically discharges cells that would benefit
    from it automatically.

    --
    To reply no_ HPMarketing Corp.
     
    Bob Salomon, Mar 16, 2005
    #7
  8. Bubbabob Guest

    "Gene" <> wrote:

    > Look on the bottom of your AA NiMH batteries,
    > if you do not see the letters stamped, "HR"
    > Then you may want to purchase a few Energizer
    > 2500 mAh at Sam's, etc.
    >
    > IMHO, the 2500mAh and the "HR" are very important :)
    >
    > I have tried discharging NiMH AAs, without success.
    > In fact, I believe that it hurts the cause to power cycle them
    >

    Definitely so. You want to avoid completely discharging NiMH batteries. I'm
    curious if the OP's battery tester was designed for carbon/zinc or akaline
    batteries (1.5v) instead of NiMH or NiCad (1.2v). This would explain the
    low readings.

    The mAh rating has NOTHING to do with the full-charge voltage.
     
    Bubbabob, Mar 16, 2005
    #8
  9. Big Bill Guest

    On 15 Mar 2005 17:41:24 -0800, wrote:

    >I have a digital camera (Canon Powershot A85) and I am interested in
    >how to more fully discharge the NiMH 2300 mAh AA batteries I use.
    >Although I have read that this type of battery is less susceptible to
    >"memory" problems, I have noticed that even though the camera indicates
    >that the batteries need to be charged, my battery tester still shows
    >them at the lower end of the lower end of the good/green range instead
    >of yellow or red. Is this normal, or is there a way to more fully
    >discharge them?


    Why do you want to discharge them?
    NiMH batteries really don't benefit from deep discharging, so why do
    it?
    "Memory" effects are very slight, if you'll notice them at all, with
    NiMH batteries.
    It seems that you're not actually having problems, and are basing your
    request on a reading from an unidentified meter; the camera has a
    built-in meter, and won't use the batteries any longer if you deep
    discharge them before charging them, so why bother?

    --
    Bill Funk
    Change "g" to "a"
     
    Big Bill, Mar 16, 2005
    #9
  10. SteveB Guest

    Digital cameras are set to turn off when the battery voltage is still 'alive
    and kicking' as it were. Otherwise they may not have enough juice left in
    them to be able to retract the lens and shut off properly. This can mean
    that the best cells in the pack never get a full or near full discharge
    though.

    Some battery chargers have a conditioning function where they fully
    discharge the cells before recharging. "Fully discharged" only needs to be
    about 1.0v as there's hardly any charge left in a cell at this point. Even
    though the memory effect isn't really a factor with NiMH there's still an
    advantage in keeping groups of cells balanced, and discharging fully
    occasionally is the best way to ensure this. As I don't have a conditioning
    charger I've made a discharger to run 4 cells down individually to about
    1.0v. It's just 4 sets of a 1 amp diode in series with a low value resistor
    (about 0.5 ohm, can't remember for sure). I know when it's finished
    discharging the cells because it gets quite warm during use and cools off
    when it's finished. When I take the batteries out they measure 1.0v.


    <> wrote in message
    news:...
    >I have a digital camera (Canon Powershot A85) and I am interested in
    > how to more fully discharge the NiMH 2300 mAh AA batteries I use.
    > Although I have read that this type of battery is less susceptible to
    > "memory" problems, I have noticed that even though the camera indicates
    > that the batteries need to be charged, my battery tester still shows
    > them at the lower end of the lower end of the good/green range instead
    > of yellow or red. Is this normal, or is there a way to more fully
    > discharge them?
    >
     
    SteveB, Mar 16, 2005
    #10
  11. Bubbabob Guest

    Big Bill <> wrote:


    > Why do you want to discharge them?
    > NiMH batteries really don't benefit from deep discharging, so why do
    > it?
    >


    Not only do they not benefit but it drastically reduces their life.
     
    Bubbabob, Mar 16, 2005
    #11
  12. Guest

    "I have a digital camera (Canon Powershot A85) and I am interested in
    how to more fully discharge the NiMH 2300 mAh AA batteries I use."

    I used to race radio controlled cars using NiCad batteries. I have a
    set of resistors on clip terminals to fully discharge each cell. I use
    a voltmeter and a notebook to see how the batteries are responding
    to conditioning and to choose which batteries to run each week.
    NiCads are know to respond well to a deep discharge, NMH are not.

    "Although I have read that this type of battery is less susceptible to
    "memory" problems, I have noticed that even though the camera indicates

    that the batteries need to be charged, my battery tester still shows
    them at the lower end of the lower end of the good/green range instead
    of yellow or red."

    Try using a real voltmeter and a small load (1K Ohms) and report back
    the
    voltage.

    "Is this normal, or is there a way to more fully discharge them?"

    As the others have said, I don't know why you want to fully discharge
    them,
    but if you really want to discharge tham, attach a 100 Ohm resistor
    between
    each cell and wait a week. Once again, I don't know why you would want
    to
    do so.
     
    , Mar 17, 2005
    #12
  13. imbsysop Guest

    On Wed, 16 Mar 2005 23:26:59 -0000, "SteveB"
    <sbrads@nildramDOTcoDOTuk> wrote:

    >Digital cameras are set to turn off when the battery voltage is still 'alive
    >and kicking' as it were. Otherwise they may not have enough juice left in
    >them to be able to retract the lens and shut off properly. This can mean
    >that the best cells in the pack never get a full or near full discharge
    >though.
    >
    >Some battery chargers have a conditioning function where they fully
    >discharge the cells before recharging. "Fully discharged" only needs to be
    >about 1.0v as there's hardly any charge left in a cell at this point. Even
    >though the memory effect isn't really a factor with NiMH there's still an
    >advantage in keeping groups of cells balanced, and discharging fully
    >occasionally is the best way to ensure this. As I don't have a conditioning
    >charger I've made a discharger to run 4 cells down individually to about
    >1.0v. It's just 4 sets of a 1 amp diode in series with a low value resistor
    >(about 0.5 ohm, can't remember for sure). I know when it's finished
    >discharging the cells because it gets quite warm during use and cools off
    >when it's finished. When I take the batteries out they measure 1.0v.


    believe it or not :) I've made an "intelligent" discharger using an
    IC comparator setup (op-amps) that compares individual cell voltage
    against a stabilised 0.95V reference and cuts off discharge (approx.
    C/15) when both are == .. and guess what ? .. I've never used it so
    far .. :)
     
    imbsysop, Mar 17, 2005
    #13
  14. Tom Gordon Guest

    Thanks to everybody for the advice. The main consensus I'm taking from
    this discussion is that I was needlessly worrying about trying to drain
    this type of battery. I also think it would be a good idea to "move the
    batteries around" (not always put the same battery in the same slot in
    the camera) since it sounds like they do not all discharge at the same
    rate nor to the same degree.
     
    Tom Gordon, Mar 18, 2005
    #14
  15. Ken Weitzel Guest

    Tom Gordon wrote:
    > Thanks to everybody for the advice. The main consensus I'm taking from
    > this discussion is that I was needlessly worrying about trying to drain
    > this type of battery. I also think it would be a good idea to "move the
    > batteries around" (not always put the same battery in the same slot in
    > the camera) since it sounds like they do not all discharge at the same
    > rate nor to the same degree.



    Hi Tom...

    It's completely irrelevant how you put them in the camera...
    they're in series.

    However, keep them in sets... soon as you buy or open
    a new package mark them somehow to make them unique.

    Then use them and charge them together.

    Ken
     
    Ken Weitzel, Mar 18, 2005
    #15
  16. Marvin Guest

    wrote:
    > I have a digital camera (Canon Powershot A85) and I am interested in
    > how to more fully discharge the NiMH 2300 mAh AA batteries I use.
    > Although I have read that this type of battery is less susceptible to
    > "memory" problems, I have noticed that even though the camera indicates
    > that the batteries need to be charged, my battery tester still shows
    > them at the lower end of the lower end of the good/green range instead
    > of yellow or red. Is this normal, or is there a way to more fully
    > discharge them?
    >

    The camera is not a battery tester. Most likely, it is indicatiing the capacity of the batteries to
    deliver the current it needs.
     
    Marvin, Mar 23, 2005
    #16
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