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describe contacts on cellphone battery??

Discussion in 'Electronic Basics' started by C. A., Jan 4, 2004.

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  1. C. A.

    C. A. Guest

    [eliminate S-P-A-M and the 'rating' if you want to reply by email,
    I'll check the newsfroup for a response, thanks.]

    I have a couple `smart' batteries from an old Motorola Startac phone
    I'd like to repurpose. The model number is SNN4904B, it's a Ni-MeH
    battery (500 MAh) and has four contact points. I'd like to:

    1. Recharge the batteries, and don't know which of the leads I should

    2. Use the batteries, and am similarly perplexed.

    One of the leads has approx. 4V out when I put a mmeter between it and
    any of the other leads. But the fact there are 3 other leads (uh) leads
    me to wonder what damage I could do to the battery if I am not careful to

    I can charge it in the old cellphone ok, but I'd like to be able to do
    it in situ with a trickle charger...

    I should mention I don't know too much about electronics -- I have a bunch
    of books though, and want to learn.


  2. <snipppety>

    Strongly suggest using the approved Motorola charger for these.
    You can probably find them on Ebay pretty cheap.

    As for 'using' them... What for? They're pretty much designed for
    the phones they're supposed to power. Considering the vast variety of
    battery types that are readily and cheaply (for the most part) available
    in the electronics world, forcibly adapting cellphone batteries for a
    different application seems to me to be a big waste of time.

    Even if it were practical, the Motorola 'smart' batteries have
    electronic components in them that interact with corresponding
    electronics in the charger. The format and means by which they interact
    are proprietary to Motorola. They don't even issue service manuals for
    the vast majority of their cellphone gear, and the chargers are no
    exception. This means no schematics, and custom IC's all over the place.

    If you really want to make a hobby of electronics, you may wish to
    consider getting your amateur radio license. Tinkering and
    experimentation is a big part of the hamateur's world (at least it is
    for those who choose to do that part of it).

    Happy hunting.

    Dr. Anton Squeegee, Director, Dutch Surrealist Plumbing Institute
    (Known to some as Bruce Lane, KC7GR)
    kyrrin a/t bluefeathertech d-o=t c&o&m
    Motorola Radio Programming & Service Available -
    "Quando Omni Flunkus Moritati" (Red Green)
  3. C. Abney

    C. Abney Guest

  4. C. Abney

    C. Abney Guest

    Well, that didn't work at all! Ok, I think I can get rid of those digraphs.

    Also I found this (through a link in another post?):


  5. gothika

    gothika Guest

    On 3 Jan 2004 18:03:32 -0700, "C. A." <>
    I have a box full of old cell phones and use the batteries for other
    things when I can.
    Here's what I do.
    If you have the charger stand match up the 2 charger contaccts with
    the 2 mating contacts on the battery. These 2 battery contacts ar the
    "discharge" contacts that you'll use to power whatever you hook up to
    them. The other 2 contacts on the battery are for sensing charge rate,
    ignore 'em.
    A simple check with a volt meter will give you the polarity if the
    battery isn't marked.
    It's best to stick with the charger that comes with the cell if you
    can, just rewire it to make it easy to hook up the battery for
    another thing about these batteries. They come in a modular plastic
    case or sometimes are "shrink wrapped" in plastic film.
    You can cut these apart to get the batteries apart for lower voltage
    On the plastic cases I use a dremel with a cutoff wheel and cut along
    the welded seam to open clamshell style.
    The shrinkwrapped ones can be cut with an exacto or utility knife.
    Then just desolder the batteries.
    You can resolder them in series for the voltage you need.
    I used small cell phone batteries to make a battery cluster for my
    remote controls, then put a sub-mini coaxial jack on the side of my
    remote to attach the charger to.
    The batteries are Nickel metal hydride so are no as vulnerable to
    memory effect. So I put the remote on charge at night when it's not in
    use insuring my remote will never go down when needed.
    Saved a fortune on remote batteries in the past year or so.
    And I always am getting more cells as businesses in my area are always
    dumping their cellulars every time they change services. Just gotta
    know where to dumpster dive.
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