Question on Recharging Time for AA NiMH batteries

Discussion in 'Digital Photography' started by eb, Apr 12, 2004.

  1. eb

    eb Guest

    I bought a very inexpensive Sakar Digital Concepts mini charger with 2
    AA 1800ma NiMH batteries from Microcenter. The charger and batteries
    work very well, and I figure I will buy new 2200 or 2400ma batteries
    separately.

    I did have a question on charging time - the charger does not give the
    recommended time. It is an "overnight" charger, not a rapid one. It
    lists output as "2x(3.2V---60mA)." How can I figure full charging time
    on 2 AA 1800ma batteries (or 2200 or 2400ma) with this charger? Thanks
    eb, Apr 12, 2004
    #1
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  2. "eb" <> wrote in message
    news:...
    > I bought a very inexpensive Sakar Digital Concepts mini charger with 2
    > AA 1800ma NiMH batteries from Microcenter. The charger and batteries
    > work very well, and I figure I will buy new 2200 or 2400ma batteries
    > separately.
    >
    > I did have a question on charging time - the charger does not give the
    > recommended time. It is an "overnight" charger, not a rapid one. It
    > lists output as "2x(3.2V---60mA)." How can I figure full charging time
    > on 2 AA 1800ma batteries (or 2200 or 2400ma) with this charger? Thanks


    In theory at least 2400mAH divided by 60mA - 40 hours. In practice, give
    it another 10- 20%. You have a 2-day charger for that capavity of
    battery!

    David
    David J Taylor, Apr 12, 2004
    #2
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  3. eb

    Bob Salomon Guest

    In article <>,
    (eb) wrote:

    > I bought a very inexpensive Sakar Digital Concepts mini charger with 2
    > AA 1800ma NiMH batteries from Microcenter. The charger and batteries
    > work very well, and I figure I will buy new 2200 or 2400ma batteries
    > separately.
    >
    > I did have a question on charging time - the charger does not give the
    > recommended time. It is an "overnight" charger, not a rapid one. It
    > lists output as "2x(3.2V---60mA)." How can I figure full charging time
    > on 2 AA 1800ma batteries (or 2200 or 2400ma) with this charger? Thanks


    The rule is to take the battery, add 40% to the capacity and divide that
    by the output to find the required time to recharge the battery.

    For example your charger will fully charge a 2200 mAh cell would take
    51.3 hours to fully charge them. However you have a charger that
    requires pairs of batteries to charge. If the batteries are at different
    states of discharge then it may stop charging the weaker one when the
    stronger one is fully charged.

    In comparison the Ansmann Digispeed charger has a charge current of 1700
    mAh on AC or DC. It takes about 1.8 hours to fully charge a 2200 cell.
    As this is a "smart charger" each cell is charged individually so one
    cell will not stop charging when another one is fully charged, and any
    number of cells can be inserted without resorting to pairs of cells.
    Further when a cell reaches full charger that cell is then switched to a
    delta V trickle charge mode so the cell does not have to be removed from
    the charger to prevent overcharging. And, as the charger uses such a
    high current for charging the charger employs an automatic fan to keep
    heat build-up to a minimum.

    The difference? Fully charged batteries and not inexpensive.

    --
    To reply no_ HPMarketing Corp.
    Bob Salomon, Apr 12, 2004
    #3
  4. eb

    Dave Cohen Guest

    That rating doesn't sound correct. I have two overnight chargers (that I no
    longer use - see below). The Rinpoche is rated 2.8v 130 ma. The Quest is
    less clear, says 3v 240 ma. I believe they mean 120 ma for each bank of two
    cells.
    I later purchased a Sakar made charger with 4 cells from Walmart, still
    available for $17. They call this Ultra-Fast, has a 700 ma rating and
    switches from fast to trickle in under 3 hrs. Comes with auto cord. While
    not the best you can't beat that price.
    As far as charge times, the overnight type will not harm cells if left on
    somewhat longer than needed. The fast charger swiches to trickle which
    should be quite safe.
    Dave Cohen

    "Bob Salomon" <> wrote in message
    news:...
    > In article <>,
    > (eb) wrote:
    >
    > > I bought a very inexpensive Sakar Digital Concepts mini charger with 2
    > > AA 1800ma NiMH batteries from Microcenter. The charger and batteries
    > > work very well, and I figure I will buy new 2200 or 2400ma batteries
    > > separately.
    > >
    > > I did have a question on charging time - the charger does not give the
    > > recommended time. It is an "overnight" charger, not a rapid one. It
    > > lists output as "2x(3.2V---60mA)." How can I figure full charging time
    > > on 2 AA 1800ma batteries (or 2200 or 2400ma) with this charger? Thanks

    >
    > The rule is to take the battery, add 40% to the capacity and divide that
    > by the output to find the required time to recharge the battery.
    >
    > For example your charger will fully charge a 2200 mAh cell would take
    > 51.3 hours to fully charge them. However you have a charger that
    > requires pairs of batteries to charge. If the batteries are at different
    > states of discharge then it may stop charging the weaker one when the
    > stronger one is fully charged.
    >
    > In comparison the Ansmann Digispeed charger has a charge current of 1700
    > mAh on AC or DC. It takes about 1.8 hours to fully charge a 2200 cell.
    > As this is a "smart charger" each cell is charged individually so one
    > cell will not stop charging when another one is fully charged, and any
    > number of cells can be inserted without resorting to pairs of cells.
    > Further when a cell reaches full charger that cell is then switched to a
    > delta V trickle charge mode so the cell does not have to be removed from
    > the charger to prevent overcharging. And, as the charger uses such a
    > high current for charging the charger employs an automatic fan to keep
    > heat build-up to a minimum.
    >
    > The difference? Fully charged batteries and not inexpensive.
    >
    > --
    > To reply no_ HPMarketing Corp.
    Dave Cohen, Apr 12, 2004
    #4
  5. eb wrote:
    > I bought a very inexpensive Sakar Digital Concepts mini charger with 2
    > AA 1800ma NiMH batteries from Microcenter. The charger and batteries
    > work very well, and I figure I will buy new 2200 or 2400ma batteries
    > separately.
    >
    > I did have a question on charging time - the charger does not give the
    > recommended time. It is an "overnight" charger, not a rapid one. It
    > lists output as "2x(3.2V---60mA)." How can I figure full charging time
    > on 2 AA 1800ma batteries (or 2200 or 2400ma) with this charger? Thanks


    I strongly suggest you invest a little money now for a good "smart"
    charger. You will save more in longer battery life and trouble than the
    cost of the charger. You also will no longer need concern yourself with
    questions like this, the charger takes care of it.

    --
    Joseph E. Meehan

    26 + 6 = 1 It's Irish Math
    Joseph Meehan, Apr 12, 2004
    #5
  6. eb

    MarkH Guest

    "Dave Cohen" <> wrote in
    news::

    > That rating doesn't sound correct. I have two overnight chargers (that
    > I no longer use - see below). The Rinpoche is rated 2.8v 130 ma.


    That would be slow on the higher capacity NiMH cells

    > The Quest is less clear, says 3v 240 ma. I believe they mean 120 ma for
    > each bank of two cells.


    240mA sounds normal. 2000mAh cells would take about 12 hours to charge
    from dead at 240mA. Remember that 240mA for a bank of 2 cells equals 240mA
    for each cell, 3V for 2 is about right, 1.5V on each battery (remember that
    while charging the cell it might be 1.5v, while draining it will be the
    1.2v written on the cell).


    --
    Mark Heyes (New Zealand)
    See my pics at http://homepages.ihug.co.nz/~markh/
    "There are 10 types of people, those that
    understand binary and those that don't"
    MarkH, Apr 13, 2004
    #6
  7. Bob Salomon <> wrote:

    >In comparison the Ansmann Digispeed charger has a charge current of 1700
    >mAh on AC or DC. It takes about 1.8 hours to fully charge a 2200 cell.
    >As this is a "smart charger" each cell is charged individually so one
    >cell will not stop charging when another one is fully charged, and any
    >number of cells can be inserted without resorting to pairs of cells.
    >Further when a cell reaches full charger that cell is then switched to a
    >delta V trickle charge mode so the cell does not have to be removed from
    >the charger to prevent overcharging.


    What happens if after the cell is fully charged, the AC power goes out
    for a few minutes?
    --
    Whenever I hear or think of the song "Great green gobs of greasy
    grimey gopher guts" I imagine my cat saying; "That sounds REALLY,
    REALLY good. I'll have some of that!"
    Daniel Prince, Apr 13, 2004
    #7
  8. eb

    Bob Salomon Guest

    In article <>,
    Daniel Prince <> wrote:

    > Bob Salomon <> wrote:
    >
    > >In comparison the Ansmann Digispeed charger has a charge current of 1700
    > >mAh on AC or DC. It takes about 1.8 hours to fully charge a 2200 cell.
    > >As this is a "smart charger" each cell is charged individually so one
    > >cell will not stop charging when another one is fully charged, and any
    > >number of cells can be inserted without resorting to pairs of cells.
    > >Further when a cell reaches full charger that cell is then switched to a
    > >delta V trickle charge mode so the cell does not have to be removed from
    > >the charger to prevent overcharging.

    >
    > What happens if after the cell is fully charged, the AC power goes out
    > for a few minutes?


    The charger is a smart charger so it checks the condition of the battery
    before charging. It then switches from rapid to delta V mode as required
    so it could briefly start to rapid charge it but it would almost
    immediately begin the delta V mode.

    With the more sophisticated Ansmann chargers like the Energy 8 and the
    Energy 16 the chargers actually indicates the state of charge as each
    cell is inserted into a chamber. A red LED would be less then 25% of
    full charger. If the LED is yellow then it has between 25 and 80% of
    full charge and if it is green it has 80% or more of full charge. As
    these are slower chargers it allows you to closely estimate the time the
    cell will take to reach full charge.

    --
    To reply no_ HPMarketing Corp.
    Bob Salomon, Apr 13, 2004
    #8
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