02-03-13 04:09 AM
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  1. Angus_CB's Avatar
    ...

    Also, in order to reduce the number of wall warts for my next trip to Europe, I've modified a 4 port, cheapo USB hub, as a 4 port high current charger hub for my cell phone, PB, GPS, and picture storage device (damn, when is RIM going to enable OTG).

    ...

    Ray
    What was modified on the USB hub?
    08-08-12 11:57 AM
  2. Nirodac Yar's Avatar
    What was modified on the USB hub?
    Basically by spec, each hub port is limited to 500mA of current. The HUB I used had it's own hard wired cable to be plugged into a computer host (thus further limiting the current to 500mA). The conductors on this cable were very small, and anything greater than 500mA would probably have released the smoke from melted the wires.

    This HUB also had provision for a barrel type DC power jack, for an external power source.
    What I modified was simply the 5 volt power trace to the 4 external receptacles for the USB cables. This bypassed any internal hub current limiting. I daisy chained a heavier wire to each receptacles, pin 1, and then back to the positive pin of the barrel jack. This gave each receptacle the maximum power available from the external power supply, plugged into the barrel jack. Ground returns on pin 4 were already heavy enough. I also shorted pins 2 & 3 on the circuit board by each receptacle.

    Be aware that 5 volts at 2 amps can cause damage, and you do this mod at your own risk.

    As it was my HUB wasn't working as it was supposed to, for data transfers. So this mod simply gives me 4, CHARGING ONLY ports for USB based devices. Please note that "Charge" only USB cables have heavier gauge wire, for handling the heavier currents.
    If your going to use a standard USB cable, make sure it can handle the higher current. Stay away from those retractable cables, and use the shortest possible cable.
    Also note that this hub shares the max power available from the wall wart. So four devices attached, can only draw 500mA each from a 2000mA wallwart. Two devices attached would be able to draw 1000mA each, and one device attached could draw the full 2000mA,etc. While you could use a 3000mA wall wart, I doubt the USB cable could handle that much current, with out releasing the smoke in the wires. Also be aware, that with 4 devices attached, when one devices completes charging, it will switch off the charge current to that device, allowing the remaining devices to share the full wall warts current. The last devices to complete charging, had better have a heavy USB cable, as it will have the full current of the wall wart available to it.

    Hope this answers your questions

    Ray
    Angus_CB likes this.
    08-08-12 01:07 PM
  3. Angus_CB's Avatar
    Thanks Ray.
    I have a few old USB 1.1 hubs that would make good candidates. A couple have the DC connector.
    08-08-12 03:41 PM
  4. bbobruns's Avatar
    I'm willing to bet five cents that a charge only cable will work.
    Absolutely. AT&T Charging cable combines lines for you. No muss, no fuss and available on Amazon.com. Don't use it for data, however. It won't work.
    08-08-12 03:55 PM
  5. wasalph's Avatar
    @Nirodac Yar: thanks for the idea... i also have those old old 1.x hub which is just collecting dust...
    02-03-13 04:09 AM
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