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cordless drill charger

Discussion in 'Electronic Repair' started by lurk, Jun 26, 2007.

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  1. lurk

    lurk Guest

    trying to trouble shoot a black/decker charging unit.....it over heats
    quick and hot......I replaced all components but still over heats....help ..
    thanks
     
  2. Smitty Two

    Smitty Two Guest

    could be the battery you're trying to charge is shorted. did you try
    more than one battery?
     
  3. lurk

    lurk Guest

    I was thinking about the battery being shorted...but not tried another
    battery yet....this is about the 3 rd charger I seen with this
    problem....they get so hot it melts the plastic....maybe they are only
    made to last so long......thanks for your response
     
  4. Guest

    After a few law suites over cordless drill charging units causing
    fires some manufacturers have intentionally made the chargers
    lightweight
    so that they will fail before any possibility of creating a fire.


    Replacement chargers that will not burn out, or get hot so easily
    are available on e-bay.
     
  5. ian field

    ian field Guest

    The B&D cordless I have can't get hot as it has a thermal fuse bound into
    the transformer primary - or at least it did until the pack developed a
    couple of shorted cells (normal for B&D!) although they do run warmer than
    you might expect in normal operation.

    You can easily tell if it has shorted cells as the transformer primary goes
    O/C and stays stone cold when plugged in.
     
  6. hr(bob)

    hr(bob) Guest

    Does the charger overheat when plugged into the AC power but no
    battery plugged into the charger?

    H. R. (Bob) Hofmann
     
  7. lurk

    lurk Guest

    It does not over heat without the battery plugged in....which makes it look
    like no load no overheat
     
  8. hr(bob)

    hr(bob) Guest

    What is the nominal voltage of the battery pack? Have you measured
    the open citrcuit voltage of the battery pack, ie just sitting on the
    bench?

    H. R. Hofmann
     
  9. John k

    John k Guest

    Does anyone know what the value is of the Thermal Fuse in the Black an
    Decker charger? I'm looking to replace mine. It's for an 18V charge
    model PS1518bu
     
  10. ian field

    ian field Guest

    All the one's I've seen (though not so far an 18V) have the thermal fuse
    bound tightly onto the surface of the primary winding and is almost
    impossible to cut away without damaging said winding.

    Usually the voltage and VA rating is marked on the wall-wart part of the
    charger, so raid the junk box for a replacement with the same ratings - I
    used a Hayes modem transformer to repair the 12V charger and an ex printer
    wall-wart for the 14.4V drill.

    Once you've replaced the O/C transformer, open the cradle section of the
    charger and check for a limiting resistor along with the 4 diodes, if you
    still have shorted cells the resistor will overheat, discolour and possibly
    change value - making it difficult to find the correct replacement, as it is
    you may have to make a "best guess" if the resistor is already discoloured
    and the value drifted.

    If you plan to attempt unsticking the shorted cells, temporarily replace the
    limiting resistor with a 10W WW and connect the partly dismantled pack to
    the charger with fly-leads. Unsticking current is supplied by parallel
    connected H4 bulb filaments from a 12V SLA battery - some cells might be a
    bit stubborn, if so short the H4 filaments for unlimited current but only
    flick the wire on!

    Take very great care to only apply the unsticking current with the correct
    polarity for each cell in turn or the short will become permanent!

    As for buying new batteries, last time I checked B&D were charging so much
    for replacements that I could have bought 2 new better spec drills for what
    B&D were charging for 1 battery! The 14.4V drill was new - I already knew
    better than buy anything else from B&D when I found the 12V drill left out
    by the bins (usual fault - S/C cells & O/C transformer). Next time they pack
    up, I buy a different brand that isn't expensive crap like B&D!
     
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