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Battery compatibilty

Discussion in 'Electronic Repair' started by [email protected], Mar 4, 2007.

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  1. Guest

    A simple query from a simpleton...

    I have a cordless house phone, whose internal batteries are worn out.
    They are feeble 700mAh NiCads who hold their charge for only a few
    minutes' use now. Can I replace them with some 2100mAh Ni-MH's, of
    which I have loads (Recommended charge 7H 420mA)? Or will they not
    charge properly on the phone's base unit (Claimed output 9V 300mA)?
    And if not, should I just replace them with exact equivalent NiCads?

    Thanks in advance.
  2. Jim Land

    Jim Land Guest

    wrote in
    Brand and model of the phone?
  3. If they fit, sure.
  4. Rob Mills

    Rob Mills Guest

    I find them at discount/closeout stores that have odd ball connectors on
    them. I cut off the connectors, splice my connector on and have a $2
    replacement that's better than the original. RM~
  5. Ken Weitzel

    Ken Weitzel Guest

    Hi Homer...

    Oops, I'd like to respectfully throw in a caveat here, if I may?

    If the phones charging contacts are at all exposed, then make durn
    sure that there's a rectifier *inside* the phone to limit current.
    Or, failing that, perhaps a very small resistor in series with the
    charging contacts.

    Otherwise something external shorting them could produce horrible
    results. I'm thinking of putting the phone in a pocket with keys
    or loose change; or the youngsters tampering with it.

    I'd also add that if the op goes this route that he seal the battery
    cover up somehow so that the kids can't "borrow" the batteries for
    their toys.

    I admit to being a little prejudiced; I still have a five year old
    scar on my leg from one 1800 mah cell shorting in my pant pocket.

    Take care.

  6. Resistor?
  7. Ken Weitzel

    Ken Weitzel Guest


    Sure, just a few ohms in series with the batteries would have virtually
    no effect while charging, but would severely limit current if they
    were inadvertently shorted?

    Take care.

  8. "rectifier" confused me.
  9. Ken Weitzel

    Ken Weitzel Guest

    Hi Homer...

    Now I'm getting confused - not at all unusual :)

    A rectifier in series with the battery pack so that it could charge from
    the external supply, but not discharge through the external charging
    contacts :)

    Take care.

  10. Eeyore

    Eeyore Guest

    I'd use those 2100mAh jobs and give them a whirl. I can't think of any way
    you'll damage anything.

  11. I have phones that can charge face up or face down.
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