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Thread: Wall Warts

  1. #1
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    Wall Warts

    I got a 500mA USB wall wart with my mod, instead of the normal 1000mA.
    Apparently the original power supplies only come with EU and US plugs, and as I'm in Australia they substituted one with AU configuration.

    I queried this and the shop assured me the supplied power supply is safe to use.

    Presumably it is a property of USB that if you try to draw more current than they can supply, the USB will ramp down the voltage. And that any device that connects to a USB port should be designed to handle this situation.

    Is this assumption correct?

  2. #2
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    Actually, I'm pretty sure the 'fixed' part is the voltage, not the current. So it should put out 5V no matter what, but limited to only putting out 500mA. A bit lethargic, but it should still work fine. Whatever is charging off it should simply take longer to charge and no harm done.

    It shouldn't reduce the voltage at all, simply put out 'only' it's maximum current and no more. Maybe a little more. Or a little less. If it's limited to 500mA it's kinda scraping the bottom of the barrel with these things...

    Stu.

  3. #3
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    Quote Originally Posted by Schtoo View Post
    Actually, I'm pretty sure the 'fixed' part is the voltage, not the current. So it should put out 5V no matter what, but limited to only putting out 500mA.
    Thanks Stu,
    I don't think the wall wart can do that, it has no idea of whats attached to it. Lets say its a 5 ohm resistor, to limit the current in the resistor to 500mA, it would have to reduce the voltage, to 2.5V. In other words, the wall wart will only apply 5V as long as the current is less than 500mA.

  4. #4
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    Quote Originally Posted by mattrix View Post
    Thanks Stu,
    I don't think the wall wart can do that, it has no idea of whats attached to it. Lets say its a 5 ohm resistor, to limit the current in the resistor to 500mA, it would have to reduce the voltage, to 2.5V. In other words, the wall wart will only apply 5V as long as the current is less than 500mA.
    Just make sure ur wall wart is not getting to hot. If ur mod is trying to draw say 1.5 amps it may get a touch warm as it tries to keep up with the draw of the mod.



    Sent from my SM-G955F using Tapatalk

  5. #5
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    my understanding is that charging a 1amp capable device with 0.5 is ok, but don't charge one that recommends 0.5 with a 1

    hopefully someone who uses usb charging comes along though
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  6. #6
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    Warts on any surface is a worry
    Walls with warts just sound scary
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    @DogMan I think you are mixing up power supplies and chargers.
    In the case of a power supply just because it can supply more current than the device needs doesn't mean it will.

    My question is do power supplies have internal protection, and how do they do it?
    OR do they just get hot and catch fire as Danny suggests.

  8. #8
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    @DogMan I think you are mixing up power supplies and chargers.
    In the case of a power supply just because it can supply more current than the device needs doesn't mean it will.

    My question is do power supplies have internal protection, and how do they do it?
    OR do they just get hot and catch fire as Danny suggests.

  9. #9
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    Quote Originally Posted by mattrix View Post
    @DogMan I think you are mixing up power supplies and chargers.
    In the case of a power supply just because it can supply more current than the device needs doesn't mean it will.

    My question is do power supplies have internal protection, and how do they do it?
    OR do they just get hot and catch fire as Danny suggests.
    I have seen one get very warm to say the least while charging a pico ( Which draws 1 amp)with a 500mah usb charger. As for one catching fire im not sure but worth the risk definitely not.


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  10. #10
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    Quote Originally Posted by mattrix View Post
    My question is do power supplies have internal protection, and how do they do it?
    OR do they just get hot and catch fire as Danny suggests.
    <insert electricians rant here>
    TLDR: ive seen some most stupidest things cause fires, electrical and otherwise.
    Anything from 0.5 amp wall chargers, a kid using a nerf gun to a 3 cent chip in a computer.
    In the words of my old man "ain't no such thing as safe, best you can hope for is haven't been screwed yet"


    But to answer your question, voltage protection requires additional tech if your paying for bargain bin crap, most wont have it because it increases the build cost.

 

 
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