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Why can't my electric stapler use Nicad batteries ?

Discussion in 'Electronic Design' started by Rodo, Oct 1, 2005.

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  1. Rodo

    Rodo Guest

    Hi all,

    I just got an inexpensive ($15) electric stapler from Staples and the manual
    says that it is ok to use alkaline batteries but not to use regular
    manganese or nickel cadmium ones. Anyone know why ? will it hurt the nicads
    if I do use them ?

    Thanks
     
  2. Not enough current and/or voltage. Nicads are 1.2 volt.
    It won't hurt but probably don't stitch either.
     
  3. Clive Tobin

    Clive Tobin Guest

    But... alkaline cells spend most of their useful life around 1.2 - 1.25
    volts also. They are 1.5 - 1.55 only when fresh. So I doubt if this is
    the answer.
     
  4. I read in sci.electronics.design that Clive Tobin <>
    wrote (in <>) about
    'Why can't my electric stapler use Nicad batteries ?', on Sat, 1 Oct
    2005:
    The other answer is that the low Ah capacity of cells, especially NiCds,
    other than hot alkalines has generated complaints about the product
    'eating batteries'.
     
  5. Jim Thompson

    Jim Thompson Guest

    Probably has to do with surge current.

    ...Jim Thompson
     
  6. Kryten

    Kryten Guest

    Nickel-based rechargables have a relatively high self-discharge rating.

    Which is not what you want in something that sits doing nothing most of the
    time, such as remote-control handsets or staplers.

    Alkaline cells will typically last a year in an IR handset, whereas
    NiCd/NiMH cells self-discharge way sooner.

    Nickel cells are best suited for things that get through cells quickly, e.g.
    power drills, Walkmans, MP3 players, etc.
     
  7. Ian Stirling

    Ian Stirling Guest

    I wonder about a very cheap mechanism, that relies on the stall torque
    of the motor to not damage the mechanism.
    Torque will be higher with NiCd at high loads.
     
  8. Phil Allison

    Phil Allison Guest

    "Jamie"

    ** On the contrary - they thrive on heavy loads.




    .......... Phil
     
  9. Phil Allison

    Phil Allison Guest

    "Rodo"

    ** The warning against Ni-Cds is most likely a safety issue.

    An alkaline AA will deliver about 10 amps if shorted while a Ni-Cd AA can
    deliver up to 50 amps - enough to burn wiring and destroy small motors.



    ......... Phil
     
  10. Engineer

    Engineer Guest

    Not so. The can deliver very high currents. That's why they are used
    in drills and screwdrivers.
    Cheers,
    Roger
     
  11. Rodo

    Rodo Guest

    This may make sense. The stapler has a small motor to do the stapling.

    Thanks .. to everyone.
     
  12. Jamie

    Jamie Guest

    Nicads don't like large loads on them.
    a stapler can produce large loads.
    and also they are lower in voltage and dont last
    as long .
     
  13. Jamie

    Jamie Guest

    i beg to differ, yes they are used in cordless screw drivers and such.
    and when it comes to high currents!, i have seen nicads blow their
    caps off from inrush of too many accurancies. the factor between
    nicads and Alkaline is that they can be recharged and that is the main
    reason whey they are used in such equipment. most devices that expect
    inrush currents are designed not to put the nicad cells into a state of
    super heating.
    the fact remains that Alkaline provides higher voltages and actually
    maintain a charge for longer periods.
    and yes, a stapler can get Alkalines hot also when used in successions.
    etc.
    P.S.
    i don't give much crecdence in Rechargeable Alkalines, i haven't found
    any yet that can maintain the life cycle like a non rechargeable type.
     
  14. ehsjr

    ehsjr Guest

    Can you post some urls that support your position?
    Ed


    yes they are used in cordless screw drivers and such.
     
  15. I suspect it is though...
    There are several that will support this. Try:
    http://www.technick.net/public/code/cp_dpage.php?aiocp_dp=guide_bpw2_c09_01
    or:
    http://www.powerstream.com/BatteryFAQ.html
    Note particularly the comments uder the NiCd type.
    Historically, this is why NiCd batteries ar still favoured, in 'traction'
    type applications (together with lead acid). There are new generation NiMh
    batteries that are starting to move into this market (look at cordless
    drills, where some makes are now moving to NiMh), and these have
    comparable or even slightly better maximum currents. There ae two 'parts'
    to this, both the relatively low internal resistance (which is what
    matters in the mobile phone application), and also relatively good
    performance from the cell as it's temperature rises. This is why
    lead-acid, or NiCd batteries are being used in current electric car
    designs, and NiCd batteries for electric flight.
    NiMh, give higher total power capacities, but it their high capacity
    versions, have higher self-disharge rates.

    As with all such things, there is a problem with 'generalisations'. High
    capacity batteries, usually have less actual electrolyte, thinner
    electrodes, and higher internal resistances. If one of these is
    substituted into an application designed for a battery supporting high
    currents, the result can very easily be cell rupture. Most manufacturers
    do both types in a specific chemistry. NiCd cells designd for traction
    use, are different 'beasties', from the sort commonly sold.

    I suspect the real problem, is in cell voltage. The original poster,
    refers to the battery as 1.5v nominal, and then points out that a
    significant percentage of it's 'life', will be spent with a working
    voltage comparable to the NiCd cell. The 1.5v nominal voltage and
    discharge curve being talked about, sounds like that for a zinc-carbon
    battery, not the alkaline cell. For medium loads, this maintains a voltage
    over 1.25v much further into the design life, than for a zinc-carbon, or
    NiCd cell. I suspect the stapler, is one of an unfortunately 'common'
    class of devices, which only uses the first perhaps 40% to 50% of the
    cells capacity, and requires the higher voltage available here, which is
    not offered by the NiCd cell...
    Best Wishes
     
  16. ehsjr

    ehsjr Guest

    Roger, I think you missed his point. He - the poster who said
    "I beg to differ" stated earlier: "Nicads don't like large loads
    on them. a stapler can produce large loads. and also they are
    lower in voltage and dont last as long . " He differs with the
    statement that nicds "can deliver very high currents. That's why
    they are used in drills and screwdrivers. "

    Ed


    Try:
     
  17. OK. I was 'differing' with the wrong person. :) However it is important
    to realise that a high capacity NiCd battery, not built for high loads,
    would then agree with the differer!. This is the big problem with such
    generalisations....

    Best Wishes
     
  18. What happened when you tried it??
     
  19. SioL

    SioL Guest

    Perhaps motor performance would suffer since nicads are only 1.2V and
    regulars are 1.5V. Can't think of any other reason.
     
  20. The design may depend on the internal resistance of the cell(s) being
    in a certain range. NiCds being lower in source impedance than
    alkalines might fry the innards.

    Before you laugh, there are plenty of LED flashlights that use the
    battery resistance as the only series resistance outside of the LED
    itself.


    Best regards,
    Spehro Pefhany
     
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