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Thread: Li-ion Battery Configuration

  1. #1

    Default Li-ion Battery Configuration

    I have a Motorola Startac Li-Ion battery pack for my cell phone (no vibrator). I'd like to recondition and charge it on my Maha charger but I'm not sure which terminals to charge at. There are 4 terminals on the battery pack. Here are some voltage and resistance measurement's I took.

    + = positive probe of multi-meter
    - = negative probe of multi-meter

    Terminal
    1 2 3 4| Volts | Resistance
    --------|--------|--------------
    + - . . | 0.00V | infinite
    - + . . | 0.00V | infinite

    + . - . |-3.56V | infinite
    - . + . | 3.56V | infinite

    + . . - | 0.00V | infinite
    - . . + | 0.00V | infinite

    . + - . |-4.06V | -38.0 k-ohm
    . - + . | 4.06V | infinite

    . + - . | 0.00V | 12.5 k-ohm
    . - + . | 0.00V | 12.5 k-ohm

    . . + - | 4.00V | infinite
    . . - + | 4.00V | -3.25 k-ohm

    Questions:
    1) what is the normal voltage of a single Li-ion cell?
    2) can someone diagram what the internals of this battery pack looks like? complete with diodes, resistors or any other devices?

    thanks for any help

  2. #2

    Default Re: Li-ion Battery Configuration

    any ideas? help?

    thanks

  3. #3
    *Flashaholic* James S's Avatar
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    Default Re: Li-ion Battery Configuration

    I recently took apart a similar 4 pinned liion batter pack from a cellphone. I think perhaps I can explain what you are seeing.

    1 pin is batt+ one is v-. On mine that is the outer most pins. The inner 2 pins are connected to plus through 2 different resistors. This is used by either the charger to monitor how much current is being put into the cell by measuring the voltage drop across them, or by the phone to measure the current being used. Or perhaps they are used by a dumber charger to reduce the charging current at extremes of temperature? I don't know for sure.

    So find the 2 terminals with the highest voltage between them and those are the regular battery terminals.

    However, I don't believe you can "recondition" a LiIon pack. Lithium batteries are good only for a limited number of charge discharge cycles and then they start loosing capacity. I am not aware of any information anywhere that says you can revive them. I believe there is a controller board inside the case of that battery that will keep you from over discharging it during a full cycle like the charger would try to do to a NiCD, but this won't help the LiIon any at all, indeed you'll just be using up another charge cycle that it has left.

    If it's no longer holding a charge then I think it's just used up. Not sure there is anything you can do about it.

    Be careful not to charge too quickly! And since my battery pack from a Samsung phone, it's terminals could be totally different, though I suspect not.

    Good Luck,
    James

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