Battery pack and charger question

Discussion in 'Electronic Basics' started by Chris W, Mar 29, 2006.

  1. Chris W

    Chris W Guest

    I have a Kenwood PB-39 9.6V NiCd battery for my Kenwood TH-G71. It has
    5 contacts on it. On the side that is in contact with the radio, there
    are 2 contacts labeled + and - so I will call them R+ and R-. On the
    back of the pack there are 3 contacts labeled, -, T and + I will call
    them B-, BT, and B+. I have a universal smart charger that will charge
    anything from a 1 to 30 cell NiCd or NiMH or similar voltage lithium and
    lead acid battery packs.. If I connect that charger to the B- and B+,
    it does nothing. Same if I hook it to any combination of the 3 contacts
    on the back. It has a way to sense if it is hooked to a battery and if
    the polarity is correct before it will start charging. If I hook the
    charger to R+ and R- it will charge, to do that I have to take the
    battery off the radio. BTW the charger is an Orbit Microlader made in
    Germany, marketed to the RC airplane industry. There is something that
    won't let the charger work right between the battery and those contacts
    on the back. I want to know what. So here is the experimenting I have
    done. With the battery in a stable state (two days since it was charged
    and no load has been applied).
    Voltage measurements.
    R+ and R- = 10.562V
    B+ and B- = 10.526V
    B+ and BT = 10.517V
    B- and BT = 0.000V

    R+ and B- = 10.560V
    R+ and BT = 10.551V
    R+ and B+ = 0V
    R- and B- = 0V
    R- and BT = 0V
    R- and B+ = 10.527

    All of these measurements were repeatable with in +/- 0.001V

    Resistance measurements.
    resistance between leads on DMM 0.30 ohms

    R- and B- = 0.30 ohms so really zero.
    R- and BT = 8.9K ohms
    R+ and B+ = meter display flashes 0L and the auto ranging graph at the
    bottom bounces back and forth.( not sure what that means)

    Other than the resistor between the negative side of the battery and the
    BT terminal what does this all tell me if anything? And more
    importantly is there anyway to trick my charger to work with the
    contacts on the back of the battery?

    --
    Chris W
    KE5GIX

    Gift Giving Made Easy
    Get the gifts you want &
    give the gifts they want
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    from anywhere, for any occasion!
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    Chris W, Mar 29, 2006
    #1
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  2. Chris W

    Chris W Guest

    Mike Y wrote:

    >Sounds like your battery has temperature detected charging. That's really
    >the
    >best way to go. I have a pulse charger for NiCads and it has a temp sensor
    >that you lay against the side of the pack. You pack appears to have it
    >built in
    >to work in the unit. There might also be some 'protections' on the external
    >contacts.
    >
    >It sounds like your RC charger is a generic pulse charger. Or even less,
    >just a current limited charger.
    >

    Nothing generic about this charger. You can hook it to you computer to
    chart the charge curve. It has 4 different charge programs for NiCd and
    NiMH batteries, it will charge every battery type I have ever heard of
    and one I have never heard of (Lithium Tadiran)


    >But if you don't know how your charger works...
    >
    >

    I do know how each charge mode works. None of them will do anything
    with this battery on the back terminals.

    >Just hook up the charger across the main battery terminals that feed power
    >to the radio. Do NOT hook up to the 'other' ground on the 'T' side. I
    >suspect
    >that .3ohm reading is NOT essentially zero!
    >
    >


    Well if I put the 2 meter leads on a clean copper plate about 1/8"
    apart, I get a reading of .25 ohms which is a difference of .05 ohms a
    dirty contact could make up for more than that. so I am willing to get
    that there is nothing between the negative side of the battery and that
    terminal. Whatever is there seems to be between the positive terminal
    of the battery and the positive contact on the back of the radio since I
    can't get the meter to give me a reading of resistance between the 2
    positive terminals, not a reading of zero, it just flashes the screen
    and won't give any reading at all. I also couldn't get my meter to give
    a capacitance reading between any pair of terminals, I didn't try to
    test capacitance on any terminal pairs that had a voltage though.

    >Yep, sounds like you're going to have to take the battery out of the
    >radio...
    >
    >Or buy the 'real' manufacturers charger that the radio 'drops into'.
    >
    >

    Since the battery is an almost worthless 600mah, I'm not going to waste
    money on a fast charger dedicated to that battery. I have a battery
    pack on the way that I think I will use as an external battery, and rig
    up a set of powerpole contacts in the alkaline battery pack for that
    radio to connect the external battery to..

    --
    Chris W
    KE5GIX

    Gift Giving Made Easy
    Get the gifts you want &
    give the gifts they want
    One stop wish list for any gift,
    from anywhere, for any occasion!
    http://thewishzone.com
    Chris W, Mar 29, 2006
    #2
    1. Advertising

  3. Chris W

    Mike Y Guest

    Sounds like your battery has temperature detected charging. That's really
    the
    best way to go. I have a pulse charger for NiCads and it has a temp sensor
    that you lay against the side of the pack. You pack appears to have it
    built in
    to work in the unit. There might also be some 'protections' on the external
    contacts.

    It sounds like your RC charger is a generic pulse charger. Or even less,
    just a current limited charger. Some of the chargers I've seen like that
    use
    high current pulses when they start up, then fall back to a constant current
    trickle charge. But if you don't know how your charger works...

    Just hook up the charger across the main battery terminals that feed power
    to the radio. Do NOT hook up to the 'other' ground on the 'T' side. I
    suspect
    that .3ohm reading is NOT essentially zero!

    Yep, sounds like you're going to have to take the battery out of the
    radio...

    Or buy the 'real' manufacturers charger that the radio 'drops into'.

    Mike

    "Chris W" <> wrote in message
    news:VbqWf.3625$fS6.1565@dukeread11...
    > I have a Kenwood PB-39 9.6V NiCd battery for my Kenwood TH-G71. It has
    > 5 contacts on it. On the side that is in contact with the radio, there
    > are 2 contacts labeled + and - so I will call them R+ and R-. On the
    > back of the pack there are 3 contacts labeled, -, T and + I will call
    > them B-, BT, and B+. I have a universal smart charger that will charge
    > anything from a 1 to 30 cell NiCd or NiMH or similar voltage lithium and
    > lead acid battery packs.. If I connect that charger to the B- and B+,
    > it does nothing. Same if I hook it to any combination of the 3 contacts
    > on the back. It has a way to sense if it is hooked to a battery and if
    > the polarity is correct before it will start charging. If I hook the
    > charger to R+ and R- it will charge, to do that I have to take the
    > battery off the radio. BTW the charger is an Orbit Microlader made in
    > Germany, marketed to the RC airplane industry. There is something that
    > won't let the charger work right between the battery and those contacts
    > on the back. I want to know what. So here is the experimenting I have
    > done. With the battery in a stable state (two days since it was charged
    > and no load has been applied).
    > Voltage measurements.
    > R+ and R- = 10.562V
    > B+ and B- = 10.526V
    > B+ and BT = 10.517V
    > B- and BT = 0.000V
    >
    > R+ and B- = 10.560V
    > R+ and BT = 10.551V
    > R+ and B+ = 0V
    > R- and B- = 0V
    > R- and BT = 0V
    > R- and B+ = 10.527
    >
    > All of these measurements were repeatable with in +/- 0.001V
    >
    > Resistance measurements.
    > resistance between leads on DMM 0.30 ohms
    >
    > R- and B- = 0.30 ohms so really zero.
    > R- and BT = 8.9K ohms
    > R+ and B+ = meter display flashes 0L and the auto ranging graph at the
    > bottom bounces back and forth.( not sure what that means)
    >
    > Other than the resistor between the negative side of the battery and the
    > BT terminal what does this all tell me if anything? And more
    > importantly is there anyway to trick my charger to work with the
    > contacts on the back of the battery?
    >
    > --
    > Chris W
    > KE5GIX
    >
    > Gift Giving Made Easy
    > Get the gifts you want &
    > give the gifts they want
    > One stop wish list for any gift,
    > from anywhere, for any occasion!
    > http://thewishzone.com
    Mike Y, Mar 29, 2006
    #3
  4. Chris W wrote:

    > Mike Y wrote:
    >
    >>Sounds like your battery has temperature detected charging. That's really
    >>the
    >>best way to go. I have a pulse charger for NiCads and it has a temp
    >>sensor
    >>that you lay against the side of the pack. You pack appears to have it
    >>built in
    >>to work in the unit. There might also be some 'protections' on the
    >>external contacts.
    >>
    >>It sounds like your RC charger is a generic pulse charger. Or even less,
    >>just a current limited charger.
    >>

    > Nothing generic about this charger. You can hook it to you computer to
    > chart the charge curve. It has 4 different charge programs for NiCd and
    > NiMH batteries, it will charge every battery type I have ever heard of
    > and one I have never heard of (Lithium Tadiran)
    >
    >
    >>But if you don't know how your charger works...
    >>
    >>

    > I do know how each charge mode works. None of them will do anything
    > with this battery on the back terminals.
    >
    >>Just hook up the charger across the main battery terminals that feed power
    >>to the radio. Do NOT hook up to the 'other' ground on the 'T' side. I
    >>suspect
    >>that .3ohm reading is NOT essentially zero!
    >>
    >>

    >
    > Well if I put the 2 meter leads on a clean copper plate about 1/8"
    > apart, I get a reading of .25 ohms which is a difference of .05 ohms a
    > dirty contact could make up for more than that. so I am willing to get
    > that there is nothing between the negative side of the battery and that
    > terminal. Whatever is there seems to be between the positive terminal
    > of the battery and the positive contact on the back of the radio since I
    > can't get the meter to give me a reading of resistance between the 2
    > positive terminals, not a reading of zero, it just flashes the screen
    > and won't give any reading at all. I also couldn't get my meter to give
    > a capacitance reading between any pair of terminals, I didn't try to
    > test capacitance on any terminal pairs that had a voltage though.
    >
    >>Yep, sounds like you're going to have to take the battery out of the
    >>radio...
    >>
    >>Or buy the 'real' manufacturers charger that the radio 'drops into'.
    >>
    >>

    > Since the battery is an almost worthless 600mah, I'm not going to waste
    > money on a fast charger dedicated to that battery. I have a battery
    > pack on the way that I think I will use as an external battery, and rig
    > up a set of powerpole contacts in the alkaline battery pack for that
    > radio to connect the external battery to..
    >


    Here are a couple of thoughts, perhaps there is a limiting resistor inside
    the battery pack. I found one in an Alinco pack that I took apart.

    You can still use the individual cells -- I am sure you know that already --
    I make it a habit to buy battery packs of all sizes, etc at yard sales. I
    disassemble them in my shop and see what is inside. Most of the time the
    AA size NiCad cells go directly to a charger and then into the kitchen
    drawer where they are used for everything from TV remotes to the answering
    machine.

    The only problem with some of the battery packs is that the terminals are
    not soldered by spot welded. I solve this problem by using a solder drop
    on top of the cut off terminal attachment and then file it so the batter
    top and bottom look like a regular AA or D or C or what ever.

    Sure this is all a bit of labor, but I now have enough batteries to power
    the city of Nashville, TN, if only I can find a way to hook it up and
    charge for it HI HI

    73's

    Dave
    N4CVX



    ~~~~~~~~~~~~~~~~~~~~~~~~
    Study History - Know the Future
    CWO4 Dave Mann, Mar 29, 2006
    #4
  5. Chris W

    Mike Y Guest

    Well, if it's a 2-terminal interface to your charger, there's only so many
    ways
    it can work. I'm not putting down your charger. I'm just saying that you
    have
    to meet the criteria the charger requires to charge effectively. And since
    the
    charger doesn't have a thermal sensor...

    If you really don't care about the battery pack, and the terminals on the
    rear
    don't HAVE to stay the way they came from the factory, but are easy to
    access, consider breaking open the pack and making the two rear terminals
    hardwire to power and ground so that you CAN easily attach to your charger.

    But keep in mind that the pack may not stay as cool 'in' the radio as it
    would
    outside the radio...
    Mike Y, Mar 29, 2006
    #5
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