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Test Power Drill Battery Charger

Discussion in 'General Electronics' started by TheKeith, Dec 28, 2003.

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  1. TheKeith

    TheKeith Guest

    I just got a new 15.6 V craftsman drill and noticed that when charging the
    nicd batteries, the do *not* get warm at all, but in the instructions, it
    says the batteries do get warm. They seem to be charged, but then they
    already had juice in them when I charged them for the first time, so I'm not
    completely sure the batteries are charging. Is there a way I can check the
    charger? I have a multimeter, if that helps. Thanks.
  2. Patch

    Patch Guest

    Run the drill until the battery is exhausted & then charge it. This will
    answer your question.
  3. TheKeith

    TheKeith Guest

    that's what I ended up doing--it works. I was just wondering if there was
    another way where I didn't have to do that, but it's already done
  4. Rich Grise

    Rich Grise Guest

    Actually, any real test that's any good does essentially the same thing

    I once made $1000.00/week + rental car + $350.00 expenses (which all went
    to expenses, imagine my surprise!) for a 2-week assignment out of town
    (in Tooele, Utah, actually - pronounced Too-Ella, not Too-Lee) where they
    had a bank of my client's battery chargers that had failed to properly
    charge about eighty-seven 55 AH fibrous ni-cd's one day. Nobody had a
    clue what was wrong, and when I asked the two guys who seemed to be running
    the show "Who's in charge here?" they each pointed at the other guy and
    said, "He is." Anyway, it turned out that the ambient temp. was about 110
    deg. F that day, and the charger/battery banks were in a metal shed. After
    a week and 4 days of basically trying to look busy, somebody (me) thought
    to ask the battery mfr's rep, and it turns out that if the batteries are
    over about 90 deg F, they won't hold a full charge. They'll _take_ a full
    charge, but only keep part of it. (I'm not sure, but it's ridiculously
    small, like 20%.)

    Anyway, these things were "battery charger/analyzers" and used a 68HC11.
    They'd charge the batteries and record the charge AH, discharge them
    through a dummy load that consisted of about 6 big heat sinks with about
    6 or 8 MOSFETS each, measure how many AH they could get out of them,
    and then charge them again. By this time, of course, so when you pour
    1.2C into them after having just pulled out 1C in about 2 hours, they
    heat up, and wind up with about a .2C charge. 'Course, if I'd asked
    the battery rep the first day, I'd have cut myself out of 2 weeks of
    gravy. :)

    If you want to be fanatical about "under operating conditions," you
    could come up with some kind of clutch/brake thingie to load the
    drill to a normal operating torque, as well.

    Have Fun!
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