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Are USB voltage and amperage internationally standarized?

Discussion in 'Laptops' started by k-risc, Mar 7, 2007.

  1. k-risc

    k-risc Guest

    Hallo,

    I am planning a trip to the US. My (german) cell phone's battery can
    be charged from an electrical outlet with a power supply unit, or via
    an USB able attached to a computer. The plug of the power supply unit
    of course only fits in electrical outlet in Germany and many other
    european countries, but not in the US. In addition, the voltage
    wouldn't be the same in the US, so I think that even with an adapter
    the power supply unit wouldn't work.

    So I was thinking about charging the cell phone at a friend's laptop
    during my stay in the US. But is the USB voltage and amperage
    internationally standarized? Or could I either break my cell phone, my
    friend's laptop, or could the charging just not work?

    Best regards,

    Christian Kirchhoff
     
    k-risc, Mar 7, 2007
    #1
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  2. k-risc

    Steve Pearce Guest

    USB specs are the same everywhere in the world.
     
    Steve Pearce, Mar 7, 2007
    #2
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  3. Are you sure? It can be worth checking what input voltage range is
    marked on the charger. Some are intentionally very forgiving.
    Yes, the USB voltage and amperage does not vary by country. (Some USB
    devices draw more current than the USB spec allows, which some laptops
    will forgive more than others; let's guess a brand-name cell phone
    charger isn't one of them?)

    (In summary: I would not hesitate to try charging mine by this means,
    but don't sue me if yours breaks. (-:)

    If you are extremely nervous, you could always get a car power adapter -
    those are the same in Germany as they are in the US (12V-ish DC,
    adequate current)?

    Have a nice trip.

    Mark.
     
    Mark T.B. Carroll, Mar 7, 2007
    #3
  4. k-risc

    M.I.5¾ Guest

    The USB supply voltage is standardised at 5 volts. However, the available
    current is dependant on the USB port. Only 100 mA is guaranteed to be
    available. Up to 500 mA can be negotiated with the controller. In general,
    root hubs and self powered hubs will allow 500 mA, but bus powered hubs will
    only allow 100 mA per port.

    Note that for firewire, the voltage is *not* specified in the IEEE-1394
    spec, but most port and peripheral suppliers have settled on 12 volts.
     
    M.I.5¾, Mar 7, 2007
    #4
  5. k-risc

    k-risc Guest

    Thanks to all of you for the fast replies.

    @Mark: Thanks for the hint about checking the voltage range of the
    charger.

    Best regards,

    Christian
     
    k-risc, Mar 7, 2007
    #5
  6. The voltage is completely standard, as is the MAXIMUM current that a
    port is supposed to supply (500ma). You can use the USB charger anywhere.

    It's very possible that your charger will work in the US with only a
    plug adapter. Check it's input ratings.

    However, a question that you didn't answer is what is the point of
    bringing the cell phone to the US at all? It's unlikely that the phone
    itself will work, which kind of makes the charger issue a moot point.
     
    Barry Watzman, Mar 7, 2007
    #6
  7. It may work fine. Europe uses GSM protocol in a particular frequency
    range, while some North American carriers also use GSM at different
    frequencies. If his phone is what is called "tri-band" or "quad-band",
    it should already support some North American frequencies.

    Dave
     
    Dave Martindale, Mar 7, 2007
    #7
  8. k-risc

    Steve Pearce Guest

    Nope, most phones will work just fine if there is a GSM provider
    available. I've used my UK mobile phone in both Arizona and Colorado
    without any problems at all.
     
    Steve Pearce, Mar 7, 2007
    #8
  9. The GSM operators charge the earth for using the cell-phone abroad or
    "roaming".
    If the US trip is any longer than simply changing planes, then a far
    cheaper option would be to get a pay as you go cellphone locally.
     
    Salvador Freemanson, Mar 7, 2007
    #9
  10. Depends on the operator. I think when visiting the UK we usually pay
    around 30c/min on our US plan, whatever it happens to be at the time.
    (Which isn't great, but could be a lot worse.)
    Or just buy a local PAYG SIM card for your existing phone.

    Mark.
     
    Mark T.B. Carroll, Mar 7, 2007
    #10
  11. k-risc

    Kevin Weaver Guest

    Why would it not work in the US ? Most likely he has a GSM Phone which
    will work in the US. CDMA Also works here along with TDMA.
     
    Kevin Weaver, Mar 8, 2007
    #11
  12. k-risc

    Ian Singer Guest

    Not sure about Germany, but most of the world is GSM and there are GSM
    networks in the States so all he needs is a new SIM card. Phones can be
    triband or quadband to work anywhere in the world.

    Ian Singer
    --


    =========================================================================
    See my homepage at http://www.iansinger.com
    hosted on http://www.1and1.com/?k_id=10623894
    All genealogy is stored in TMG from http://www.whollygenes.com
    Charts and searching using TNG from http://www.tngsitebuilding.com
    I am near Toronto Canada, can I tell where you are from your reply?
    =========================================================================
     
    Ian Singer, Mar 8, 2007
    #12
  13. k-risc

    Ian Singer Guest

    Salvador Freemanson wrote:

    When I went to England from Canada I purchased O2 SIM cards from ebay
    and picked up cheap GSM triband phones there. The cards were great and
    included unlimited evening talk time for x weeks and we really used them
    all. Phones now being used here with Canadian SIMS. Looking for source
    or cheap ones for use in California though.

    Ian Singer

    --


    =========================================================================
    See my homepage at http://www.iansinger.com
    hosted on http://www.1and1.com/?k_id=10623894
    All genealogy is stored in TMG from http://www.whollygenes.com
    Charts and searching using TNG from http://www.tngsitebuilding.com
    I am near Toronto Canada, can I tell where you are from your reply?
    =========================================================================
     
    Ian Singer, Mar 8, 2007
    #13
  14. k-risc

    M.I.5¾ Guest

    'Most (european) phones' will only work if they support the US GSM
    frequencies (they are completely different to the rest of the planet). The
    have to be 'tri-band' or 'quad-band'. Single or dual-band phones won't
    work. I would suggest your phone is at least tri-band (they don't always
    make this prominent).
     
    M.I.5¾, Mar 8, 2007
    #14
  15. k-risc

    M.I.5¾ Guest

    There are 4 different GSM systems in use. The US* uses a unique frequency
    band. The West Indies* uses yet another. The rest of the planet has
    standardised on the original GSM 800 with a few providers using a fourth
    higher band. Many less than new European phones don't support the US and WI
    standards.

    *Of the US and the West Indies, one uses GSM 1800 and the other uses GSM
    1900, but I can't remember which is which.
     
    M.I.5¾, Mar 8, 2007
    #15
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