Question about NiMH battery capacity

Discussion in 'Digital Cameras' started by R.F. Burns, Nov 4, 2003.

  1. R.F. Burns

    R.F. Burns Guest

    Either I've got a bad charger, a bad batch of batteries, or I just don't know
    how to read this battery charger. I've got a MH-C777PLUS charger/analyzer.
    I've got AA batteries, each supposed to be 1800mAh. When I discharge and
    recharge a pack of 4 of these batteries, what would you expect the mAh
    reading to display? 1800, 3600, 7200, something else?

    The display reads 2.4 volts, but sometimes it only charges 15-20 mins and
    reads 300 mAh after charging what I thought were dead batteries.

    I know it's a basic question, but thanks for any help.
     
    R.F. Burns, Nov 4, 2003
    #1
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  2. This is 4 cells in series, right? If so, the pack is 1800 mAh 4.8 V.
    If the voltage is 2.4 volts, two of the four cells are either completely
    discharged or shorted. If they're just discharged, a minute or two of
    charging should raise the pack voltage to around 4.8 V. If it remains
    at 2.4 V, the bad cells are shorted and they will just stay at 0 V.

    You can use a high-current pulse (typically from discharging a
    capacitor) to clear the short in the bad cells, but they will probably
    die again soon anyway.

    Dave
     
    Dave Martindale, Nov 4, 2003
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  3. R.F. Burns

    R.F. Burns Guest

    Thanks for the help. Since I know now that the charger should be showing
    4.8v, I started checking the charger, the batteries, and the battery pack.
    I found I had been using the wrong terminals on the plastic pack I put the AA
    batteries in. They were the only terminals that ever worked, though. I
    realized the terminals I was supposed to be using had a continuity problem.
    I pryed and pushed on the terminals some, loaded the batteries back in, and
    the correct terminals now work and read 4.8v like it should. And to think
    all this time, I've only been charging 2 of the batteries!!

    Thanks for the help!
     
    R.F. Burns, Nov 4, 2003
    #3
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