Ni-MH queries (over- and under- charching)

Discussion in 'Digital Photography' started by Prateek, Dec 30, 2004.

  1. Prateek

    Prateek Guest

    I have some queries regarding Ni-MH batteries which I use for my
    digital camera:

    1. Are Ni-MH batteries affected by overcharging?
    2. What exactly is overcharging? I have a rapid charger which indicates
    by an LED that the batteries are fully charged. If I keep the batteries
    on the charger after that, does that constitute over-charging?
    3. How about removing the batteries before they are fully charged? Does
    that affect battery life? Also, does the rate of charging decrease as
    the battery charge increases?

    Thanks

    Prateek
    Prateek, Dec 30, 2004
    #1
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  2. Prateek

    Bob Salomon Guest

    In article <>,
    "Prateek" <> wrote:

    > I have some queries regarding Ni-MH batteries which I use for my
    > digital camera:
    >
    > 1. Are Ni-MH batteries affected by overcharging?
    > 2. What exactly is overcharging? I have a rapid charger which indicates
    > by an LED that the batteries are fully charged. If I keep the batteries
    > on the charger after that, does that constitute over-charging?
    > 3. How about removing the batteries before they are fully charged? Does
    > that affect battery life? Also, does the rate of charging decrease as
    > the battery charge increases?
    >
    > Thanks
    >
    > Prateek


    This all depends on your charger's specifications. Go to www.ansmann.de
    for descriptions of various types.

    --
    To reply no_ HPMarketing Corp.
    Bob Salomon, Dec 30, 2004
    #2
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  3. Prateek

    Dave Cohen Guest

    If the charger switches to a trickle charge mode continued charging will do
    no harm and may in fact more fully charge the batteries - depends on
    charger. Heat is a good indicator. On my 3 hour charger cells get warm but
    not so hot as you can't hold them to your cheek. I don't like chargers which
    get cells hot regardless of mfgr's claims.
    Dave Cohen

    "Bob Salomon" <> wrote in message
    news:...
    > In article <>,
    > "Prateek" <> wrote:
    >
    >> I have some queries regarding Ni-MH batteries which I use for my
    >> digital camera:
    >>
    >> 1. Are Ni-MH batteries affected by overcharging?
    >> 2. What exactly is overcharging? I have a rapid charger which indicates
    >> by an LED that the batteries are fully charged. If I keep the batteries
    >> on the charger after that, does that constitute over-charging?
    >> 3. How about removing the batteries before they are fully charged? Does
    >> that affect battery life? Also, does the rate of charging decrease as
    >> the battery charge increases?
    >>
    >> Thanks
    >>
    >> Prateek

    >
    > This all depends on your charger's specifications. Go to www.ansmann.de
    > for descriptions of various types.
    >
    > --
    > To reply no_ HPMarketing Corp.
    Dave Cohen, Dec 30, 2004
    #3
  4. Prateek

    Jerry G. Guest

    "Prateek" <> wrote in message
    news:...
    I have some queries regarding Ni-MH batteries which I use for my
    digital camera:

    1. Are Ni-MH batteries affected by overcharging?

    Overcharging will cause the batteries to heat up too much, thus doing
    internal damage to their internal structure, and chemicals.


    2. What exactly is overcharging? I have a rapid charger which indicates
    by an LED that the batteries are fully charged. If I keep the batteries
    on the charger after that, does that constitute over-charging?

    Overcharging is when the charger is keeping the charge current high, and
    this is actualy over saturating the internal chemicals in the battery. It is
    in effect, "internaly cooking" the battery.


    3. How about removing the batteries before they are fully charged? Does
    that affect battery life? Also, does the rate of charging decrease as
    the battery charge increases?

    The best efficiency is to remove the batteries when they are properly
    charged. Removing them before they are fully charged, does not allow them to
    chemicaly reach their full saturation, and thus may produce less total
    lifespan. As for the lithium based batteries, when charging them before they
    are fully discharged, they do not have a "battery memory" problem. The
    standard NiCad battery type will have a memory problem is not properly
    cycled.

    Good quality chargers have a mode where they will go in to a standby charge
    when the battery is fully charged. In this mode, the charger will only put
    out enough charge current to maintain the battery charge, or only cycle
    charge as needed to keep the battery maintained. This type of charger has
    the internal means to know the charged condition of the battery, in order to
    determine the proper charge requirement of the battery. With this type of
    charger unit, the battery can be left on charge for an indefinate period of
    time.

    An example of a device that has this type of charger system, but for a high
    capacity of load, is a UPS. There are many other types of consumer type
    product chargers that have an automatic mode for maintaining a battery on
    charge without overcharging it.

    Most of these standard chargeable batteries should last about 2 to 4 years,
    or about 1000 charge cycles. Under test conditions, many of these batteries
    showed a slight deteriation starting after about 350 to 450 charge cycles.
    When the battery is new, it reaches its peak performance after about 7 to 10
    charge cycles. Then it is slowly going down over the remainder of charge
    cycles that it will last. After a certain amount, its rate of performance
    will increase rapidly.

    The conditions of use, such as the frequency of use, the load current, the
    charge current, the operating temperatures, atmospheric pressure, physical
    handling (dropping or banging), and humidty, are usage and environmental
    factors that will determine the total life of a battery.

    The average is about 3 years of usage, or shelf life. After 3 years with any
    battery, it will be at or near the end of its life.

    Jerry Greenberg. (GLG Technlogies GLG)

    --


    Thanks

    Prateek
    Jerry G., Dec 30, 2004
    #4
  5. Prateek

    Harvey Guest

    "Prateek" <> wrote in message
    news:...
    > I have some queries regarding Ni-MH batteries which I use for my
    > digital camera:
    >
    > 1. Are Ni-MH batteries affected by overcharging?


    Yes they are. If overcharged their life will be shortened as the chemicals
    inside tend to boil off and the battery vents.

    > 2. What exactly is overcharging? I have a rapid charger which indicates
    > by an LED that the batteries are fully charged. If I keep the batteries
    > on the charger after that, does that constitute over-charging?


    No. A well designed charger will not overcharge if left on for additional
    hours. I would remove the batteries soon however and not let them stay
    there for weeks on end.

    > 3. How about removing the batteries before they are fully charged? Does
    > that affect battery life?


    Removing batteries before fully charged does not have a measureable effect
    on life. It will only affect the number of camera shots during that
    specific charge cycle.

    Also, does the rate of charging decrease as
    > the battery charge increases?


    Perhaps very slightly. But most chargers are either constant current or
    pulsed. They pretty much go full bore and then when they sense a full
    charge they shut right down. Some of the more advanced chargers may then
    apply a small maintenance, or trickle charge, to keep them topped off.


    >
    > Thanks
    >
    > Prateek
    >
    Harvey, Dec 30, 2004
    #5
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