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recharging a custom-made battery pack

Discussion in 'Electronic Basics' started by [email protected], Aug 20, 2005.

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  1. Guest

    Is it possible to recharge a custom-made battery pack?


    I've used a four-AA batter case from radio shack to build a battery
    pack for electronic devices (walkmans, MP3 players, digital cameras,

    Every time I need to reacharge the batteries, I must unscrew the batter
    case, remove the four AA Energizer 2500mah batteries, place them in a
    charger, and then reassemble everything several hours later.

    I would like to be able to find a way simply to connect the battery
    pack to a standard 5-hour battery charger. I figured I could do this
    by creating some kind of dummy battery with leads connected to the
    battery pack. The dummy battery could be placed in one chamber of any
    good quality battery charger that senses when to turn off oro trickle

    My big question:

    Is this possible without creating any special circuitry?

    Thanks for the help.

  2. kell

    kell Guest

    You won't need any special circuitry, but you have to get the right
    charger. You have a 4.8 volt 2500 mAH battery that you need to charge.
    Is it Ni-Cad or NiMH? Find a charger for the same kind of battery.
  3. Jasen Betts

    Jasen Betts Guest

    if you can find a charger that will charge the 4 cells while they're
    connected in series it is,

    many chargers only charge pairs of cells.

  4. Guest

    Thanks for your replies.

    I've got a good battery charger that will charge AA, D, C, and AAA of
    any mah. It charges pairs in series, but I don't see why it wouldn't
    charge 4 batteries in series; it will just take double the time.

  5. ehsjr

    ehsjr Guest

    The problem is the 5 hour spec. If you are willing to go for
    14 hours, you can make a charger with 4 parts:
    an LM317 IC, R1 a 5 ohm 1 watt (or higher) resistor, D1, a
    1N400x diode and a heat sink for the LM317, plus a 12 V wall

    in ------- out
    +12 -------| LM317 |-----+
    ------- |
    |adj [R1]
    | | D1
    +---------+--->|--- To Battery plus

    Gnd ------------------------------ To Battery negative

    You can add a mechanical timer and plug the wall
    wart into it if you want, to set the charge time to
    14 hours. The charger is designed for 2500 maH cells.
    Do not use it for cells of a lower rating.

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