A desktop fridge made from a peltier cooler which the builder insists can be powered through a USB port (though I wonder).

$5 Mini USB Fridge! – Link

12 thoughts on “USB-powered desktop cooler

  1. While lots of things can be powered through a USB port, the danger of killing your power supply isn’t worth saving $3 or pulling a wall-wart out of your junk pile.

    Since he didn’t say, and since someone might try it, DO NOT use a laptop with this.

  2. The USB 2.0 standard stipulates that Host ports (like the USB ports on your computer) must provide 5V at 500mA (or 2.5W) per port, to power mice, keyboards etc.

    So the cooler will work….a little.

    My Maxtor desktop backup drive uses two USB cables; one for USB and power, the other one just for power. In theory you could plug the cooler in to all USB ports, and get 6×2.5=15W.

    Important note: some notebooks assume you’ll never use all ports at max power all the time! So don’t use your laptop as a portable 5V power supply. Then again….

  3. wsuverkropp says, “The USB 2.0 standard stipulates that Host ports (like the USB ports on your computer) must provide 5V at 500mA (or 2.5W) per port …”

    That’s not the whole story.

    Per the USB spec, the port provides up to 100 mA before a device is plugged in. Once a device is plugged in, it is enumerated (the computer asks the device what it is, etc) and the device tells the host how much current it needs, up to 500 mA. If the device asks for more than 100 mA and if such current is available (and you cannot get more than 100 mA per port on a bus-powered hub or some laptop ports when on battery power), only then will the computer allow the device to draw more than 100 mA. If the device requests more than 100 mA and that current is not available, the device is shut down.

    Back to “USB Powered” Coolers, lamps, and other such things that completely violate the USB spec: since these things aren’t true USB Devices and as such are not enumerated, the maximum current available to them will be 100 mA. The rub is that these things don’t have any current limiters or protection, so hopefully they won’t damage your computer’s USB ports.

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Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. And he has a new best-of writing collection and “lazy man’s memoir,” called Borg Like Me.

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