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Charging a NiCd battery pack

Discussion in 'Misc Electronics' started by shred00, Sep 16, 2006.

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  1. shred00

    shred00 Guest

    I have a NiCd battery. The charger that came with it seems to have
    given up the ghost (died) and I need to charge this battery.

    This battery a 14.4v battery pack and I am told by the manufacturer
    that it has a 1.5Ah capacity. The charger that comes with the battery
    recommends charging for 3-6h so it seems like they are doing a C/3-C/5
    charge.

    I have a battery charger that has selectable charging voltages and
    current, but it only goes up to ~10v. I'm assuming this is no good to
    me for this battery pack as I'm assuming I *have* to charge at the full
    14.4v for the required time given the selected current (i.e. the C/n
    charge rate).

    I do have available to me a DC power supply that allows me to select
    (i.e. via analog dials) both output voltage and current. Would this be
    suitable to charge this battery pack? Should the voltage be set at
    14.4v or some value lower/higher?

    Thanx,
    b.
     

  2. Do what I do. Stick an analog meter in series and charge at a reasonable
    rate while watching the current.
     
  3. shred00

    shred00 Guest

    Does it have to be analog? Can I use digital? I only have digital
    meters.

    Will putting a digital meter on the + and - output of the power supply
    and setting the meter for the correct DC range read the current being
    supplied from the power supply? Or do I have to have a load on as
    well? I would think the latter since the current has be being drawn by
    a load yes? (i know next to nothing about electronics/electricity as
    you can see)

    b.
     
  4. Sure, but some DMMs turn off after a period.
    No. You need to put the meter in series to read current. And you'll need a
    little more voltage with a DMM because they usually drop more volts than an
    analog meter.
    http://hobby-electronics.info/course/ from another poster here.
     
  5. jasen

    jasen Guest

    analog meters typically cost less to run.
    stick it in series with the batteries. use the 10A range.
    without the load the meter onb the amps scale behaves like a short circuit
    and something will possibly be damaged.
     
  6. shred00

    shred00 Guest

    I tried this. I put the meter between the + output of the power supply
    and the battery and the DMM read nothing. I also tried connecting the
    device to the power supply with the DMM between the + of the power
    supply and the + of the device and turned on the device. The device
    didn't work and the DMM read nothing. The device works on the power
    supply without the DMM in series.

    I also tried putting the DMM between a charged battery and the device
    so that the DMM was between the + terminal of the battery and the
    device and again the device didn't work an the DMM read 0 while the
    device was on.

    I feel like I am missing something fundamental.

    b.
     
  7. Did you switch the DMM to a current range AND plug the probe into the
    current socket on the DMM?
     
  8. shred00

    shred00 Guest

    Sure did.

    Black lead to COM, red lead to the non-10A input.

    Set the DMM to read DC current (in the range labeled with an "A" with a
    solid and dashed line above it) on the "200m" setting (200 milli-apms
    IIUC).

    Now wait. I just tried the red lead in the 10A plug and setting the
    10A selector on the DMM and when I set the bench supply to .15 (amps) I
    do read 0.15 on the DMM. I wonder why it reads 0.00 with the red lead
    in the (up to 200mA) socket and the 200m selected on the DMM but fine
    in the 10A plug. Strange.

    Looks like I am charging now. I'm assuming the DMM continues to
    conduct the current when it's switched off.
     
  9. Not an assumption I would make although it may be true. That's why I prefer
    an analog meter for this.
     
  10. Sounds like you blew the fuse in the meter's 200mA input circuit.
     
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