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Inverter or laptop power adapter?

Discussion in 'Electrical Engineering' started by no_one, Sep 16, 2007.

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  1. no_one

    no_one Guest

    A friend lives on a boat with 12V power when he is not at the dock. He
    needs to run his laptop (dell inspiron) while out at sea. He had problems
    with a Radio Shack inverter (no suprise here) that finally blew itself up in
    a large puff of smoke. His options are a new (hopefully better quality)
    inverter or a laptop power adapter that runs from 12 volts and produces the
    correct DC power to directly supply and charge the laptop. I have been
    looking at names like Cyber Power and Targus and they seem to have suitable
    units for the job.

    Any opinions on which is the better solution? It seems to me that the DC-DC
    (adapter) would be simpler than the need to chop and form 115vac which will
    go to still another adapter to provide the DC that the laptop actually will

    Thanks for any help


  2. Tell him to just go buy a honda generator or something similar that can
    power a bunch of things.
  3. no_one

    no_one Guest

    too small a boat; not a good solution but thanks
  4. no_one

    no_one Guest

    Good feedback, thanks. I have the same opinion of RS and wanted to steer my
    friend clear of them in the future.
    What about power quality of the inverter output? Should one be concerned
    or do modern inverters provide a clean enough output for laptop and other
    uses? Any problems driving motors (refrigerators, fans, etc) within the
    wattage limitations of the unit?

  5. Most UPSs for computers utilize 12V battery systems inside them.

    You could take a small, fully charged UPS onto the boat, and turn it on
    when needed, which should yield at least a few hours of 120V operation.
    You'd have to mute the alarm though. It would think it was operating
    during a power outage, and the batteries are made for such deep cycling
    type operation. Perfect solution.
  6. Check out this company:

    [8~{} Uncle Monster
  7. no_one

    no_one Guest

    Thanks for the input; I was concerned that the square wave outputs could
    cause stress on the load device but you have convinced me that that should
    not be a concern with this application.

    I agree with you that if it appears to be too good a price then it probably

  8. Palindrome

    Palindrome Guest

    Michael A. Terrell wrote:
    Many do. Many do not and have a run switch that will start up the UPS
    without any mains supply. Those that don't are usually fairly easy to
    modify so that they will start up without a supply present. A typical
    mod is as simple as a momentary-action switch wired across a set of
    relay contacts.
  9. Palindrome

    Palindrome Guest

    Even the swish ones that do a lot of line quality monitoring will start
    the inverter up when plugged into an out-of-tolerance supply. The
    /supply present/ signal to the uproc is often either an opto-isolated
    logic level or a relay contact. Faking one of those with a momentary
    contact switch will get the uproc acting as if it has a supply present
    and it will start monitoring the input supply - which, with no supply
    present will cause the inverter to start up.

    Another thing to look out for is a (test) jumper on (one of) the pec(s).
    I haven't come across a modern one without one - although I seldom see
    anything <1kVA.
  10. Bullshit. I have UPSs that will turn on in backup/recover mode when
    there is no AC power detected, and if it ain't plugged in, guess what,
    asswipe... no AC gets detected, dipshit.

    Another power supply that YOU made a retarded ASSumption about.

    Par for the course with a weenie fucktard like you.

  11. Note where I said it was only good for a couple of hours, and not even
    if under full load.

    **** off, asswipe. It ain't for your house lights.

  12. Most will run from the moment their main switch is activated if their
    battery is up, and there is no AC detected.

    Thank you for the confirmation.
  13. Palindrome

    Palindrome Guest

    IME, for modern UPS, *some* will do something similar but certainly not
    most - as due to what I can only assume is a cost-saving measure, they
    often don't have a "test" or "start" button. So they just sit there
    doing absolutely nothing until connected to a supply, no matter what
    position the main switch is in.

    I haven't actually come across one that runs immediately on operating
    the main switch, with no power connected. A make and model of one that
    does so would be appreciated. The nearest to that I have seen is one
    with a "start" button, right next to the main switch.

    Another thing for the OP to consider is that UPS tend to use several 12v
    batteries in series, to create an internal dc supply of 48v or higher.
    Whereas an inverter is usually designed to run off 12 or 24v. So an
    inverter can be a whole lot easier to hook up to the odd big deep
    discharge battery, or even a car battery or two, at a push.

    Also many small UPS have been designed only to run for the length of
    time determined by their internal batteries. On high load they get very
    hot internally, but the battery energy runs out before the internal
    temperatures rise to unsafe levels. Mod those to run off an external
    battery supply and they trip thermal (often non-resettable) fuses - if
    you are lucky..

    Me, I like to use a genny and an inverter and batteries- especially
    these tiny ones that use electronics to produce the output sine wave and
    allow the motor speed to change with load. Even a small one will work
    well with a battery/ inverter combination. Whereas you need a much
    larger regular genny to do that, because of the voltage peak truncation
    effect of load on small gennys.

  14. Idiot. When they have clean power they DO NOT start at all.

    It is when the power sags or fails completely that they begin to
    perform their job. D'oh!
  15. no_one

    no_one Guest

    My friend decided to go with the 100W Anyplug adapter from Targus; It will
    run from 110VAC, 12VDC, and whatever DC is used on commercial aircraft. I
    appreciate all the info and opinions; I knew going in that there were
    several ways to skin the cat and wanted to hear what others might do.

    Again Thanks
  16. Palindrome

    Palindrome Guest

    I suspect that they already know that UPS come in three flavours:
    line-interactive, online and oiffline and that various manufacturers
    make different types - some producing all three types.

    Even within each type, there are very many different designs. Designs
    for medium sized (2kVA<>10kVA ) tending to be rather different than
    those <2kVA and >10kVA.

    The poster you are replying to seems to be talking about his experience
    with <1kVA units. Units that I rarely see so am quite prepared to accept
    that they are difficult to get to start up without a good supply. I can
    see that end of the market being very price-sensitive, so extra bells
    and whistles, like a start button are not worth including. Also, I
    assume that they mostly have very limited run time and are only intended
    to smooth out power glitches and shut their systems down gracefully -
    not run the system for tens of minutes/hours during an outage. So not
    much use as a battery+inverter when no supply is present, even if they
    could be started.
  17. Palindrome

    Palindrome Guest

    One of the main manufacturers of floating gin palaces is just down the
    road from me, in Plymouth (UK):

    OK, not exactly "small boats". But they have oodles of amps...
  18. krw

    krw Guest

    Well, ballast is often made out of lead. ;-)
  19. krw

    krw Guest

    Been to one of Dimbulb's parties?
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