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Car Chargers Keep Blowing Out

Discussion in 'Electronic Basics' started by [email protected], Apr 10, 2006.

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  1. Guest

    I got SIRIUS satellite car kit which plugs into the electrical outlets
    in my Honda Accord (2004) and the first one died after less than a
    week, then I exchanged it for a new charger and that one died in 5
    minutes. I was then thrilled to find that a charger I have for another
    device matches the specifications of the Sirius charger, so was using
    that and now this morning that charger is dead. I'm starting to wonder
    if maybe a power surge is causing this? Should I always unplug these
    chargers when I turn off the car, and not plug them in again until the
    car has been started? I took the one charger apart...can I repair it
    by just replacing the little cylinder fuse inside? Are they easy to
    find? Any help would be appreciated.
  2. I would say it's your sirius that has a problem...
  3. Guest

    Could you elaborate , please? Also, I should note that this has
    happened with two Sirius radios (same model). When I first exchanged
    the car charger I also was forced to exchange the radio (inventory /
    return conditions).
  4. OK, I'll have a stab.
    I think that the sirius probably has a surge current, or a strange effect
    when it is first turned on...
    If you're blowing chargers then i'm inclined to believe that it's not the
    chargers that are incorrect, but that they're being overstressed when you
    start the car. So either:

    1. Siruis is drawing too much current on turn on
    2. Car voltage supply is exceeding maximum input voltage for charger on turn

    Would help to know what the sirius and charger make and numbers are and what
    exactly the fuse protects.

    If you say that the sirius is changed too, it could be a design flaw, or it
    could be your Honda has a wobbly 12V when you turn it on. But i'd not think
    that was a likely candidate.

  5. Chris

    Chris Guest

    Hi, Jeff. Mr. Todd has given good advice. But if you happen to have a
    voltmeter, check something else, too. Turn on the engine, then with
    all the accessories off, read the battery voltage. (Be careful to keep
    the DVM leads away from the fan and moving parts). If you're reading
    much over 14.2V, it's possible your Honda voltage regulator may have
    gone south. The high voltage could be stressing your plug-in power
    adaptor, causing it to fail.

    Voltage regulator problems sometimes take a bit of time to kill the
    battery, but especially if your car is starting sluggishly or you find
    yourself needing a jump start, that's something else to look at.

    You may also want to look inside the cigarette lighter socket for a
    burned connection. If something pitted the pin contact in the middle
    of the socket, that could cause an intermittent electrical contact
    which could also kill the adapter. The socket is easy to replace (make
    sure you diisconnect the car battery before attempting this).

    After you've cleared these things up, you might want to go with an OEM
    adapter from Sirius. They're not that much more expensive.

    Good luck
  6. ehsjr

    ehsjr Guest

    It may be a spike that is causing the problem.
    At a minimum, put a 1.5KE15A transorb across
    (banded end to + ) the input to the charger.

    Some people recommend using 2 transorbs - one
    rated at 15 volts like the 1.5KE15A, and one
    rated a lot higher, like the 27 volt 1.5KE27A,
    both in parallel across the input.

  7. w_tom

    w_tom Guest

    If a power surge caused your problem, as detailed in the other
    newsgroup ( where this same poblem was posted - how
    great must 12 volts increase and not cause damage? Even 15 volts is
    well below what any electronics must withstand without damage. Any
    replied should have known that. Sirrius hardware design is a more
    likely suspect - bad design.

    I looked at what is being sold in Radio Shack. Now that Radio Shack
    is more dominated by bean counters - which is why they are doing so
    badly - not corporate management with technical background - now Radio
    Shack starves us of basic facts. For example, what is the output
    current for a Sirruis AC adapter? RS cannot be bothered to provide
    useful information even on the box - a corporate bias that you are and
    should remain technically naive.

    So I look at the size of those adaptors. Only using ballpark
    estminates and decades of experience, that 2 amp fuse may be too small
    - a design error.

    Now we discuss what all responders here should know. Does a 2 amp
    fuse blow at 2.5 amps? Of course not. Fuses follow a well defined and
    commonly known curve - I squared t - current squared times time. If a
    power supply outputs 2 amps constant, then its fuse should be three or
    four amps. Maybe larger is the load current varies significantly. 2
    amp fuse may blow after maybe 24 hours of operation at 2 amps.

    Let's say lower auto voltage during starting causes adaptor to draw
    increased current. Then we demand a number. A 2 amp load might
    increase to 2.3 or 2.5 amps for a short time (notice time is also a
    necessary parameter). Fuse then can provide 2 amps for years should
    then not blow at 3 amps for a short period - if properly sized when
    designed AND confirmed by top management in the design review.

    In short, I suspect design used a fuse too small. But again, since
    Radio Shack now shows contempt for the technically literate, then they
    don't put any numbers on those many Sirrius adaptors. No numbers on
    that AC adapter suggests the AC adaptor would not be UL approved -
    another indication of inferior design.

    No way a power outlet has any relationship to a fuse that blows
    inside the Sirrius adaptor. Another suggested a weak Honda outlet
    caused lower voltage and therefore increased current. Good until we
    apply numbers and the I squared T relationship - how fuses are sized.
    With numbers, then a subjective idea has no merit.

    Due to a disrespect for the more technically informed (by Radio
    Shack), then your responses are speculation. However some speculation
    is based in science. Other speculation - such as the Honda createing a
    surge too large - is total bullshit.

    Try a 3 amp fast blo type fuse - 32 or 250 volts. Also posted
    elsewhere was as kludge solution involving automatically resetting
    fuses. I am surprised you did not ask for details - instead jump on
    nonsense ideas such as surges. However the automatically resetable
    fuse may be slightly too large.
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