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I have an old USB 1.1 hub that I was wondering if could be repurposed to something useful. Would it be possible to connect it to a wall charger with USB outlet and use the hub to get 4 USB charging ports? Or does USB hubs not like being connected to wall outlets? The image below shows a hub similar to the USB 1.1 hub I have.

UPDATE: I did try this on some devices and the conclusion is as follows: My old Android 2.3 device will charge, albeit very slowly. My iPhone 5S will not charge at all. USB hub

  • what was the result of trying it? – Skaperen Mar 28 '15 at 9:20
  • Just make sure the wall charger you connect it to is a quality one - genuine Belkin or Apple will be good. Just don't use no-name chinese crap, they are dangerous (and that applies to all of them, not just counterfeit Apple chargers). – user256743 Mar 28 '15 at 13:25
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    Its probably USB 1.1, not 1.0 - 1.0 is VERY uncommon apparently – Journeyman Geek Mar 28 '15 at 13:27
  • @JourneymanGeek You are surely right about that. I've updated the post. :-) – user1049697 Mar 28 '15 at 14:21
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    Best household items I've used are: a Smart TV and an Xbox One. My Smart TV seems to charge about 80% as fast as a direct-to-wall connection. – Dom Mar 28 '15 at 14:46
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Unfortunately, it really depends on the specifics of the implementation of both the hub and device.

Now, the vast majority of simple hubs don't really implement any sort of power control. They'll just connect the USB power lines directly to either their host or an external (regulated) power supply, which means you'd effectively be sharing the capacity of the power source over all ports.

In practice, however, USB charging gets quite complex. The bottom line is: your USB 1.1 hub will probably charge your peripherals, but at a reduced rate. This isn't because the hub is actively limiting the current output, but because peripherals will limit the current they draw unless they can positively confirm the host is capable of supplying that current - to prevent damage to hosts that can't.

Now, this reduced rate depends on the specific peripheral, and also on the specific hub - but it likely ranges from 100 mA to 500 mA, which is far less than a modern smartphone's max over 1000 mA.


To elaborate:

  • If the host implements some kind of power control, then the peripheral must initiate a data connection and negotiate properly. Even though this is technically required by spec (except the newer battery charging specs), some peripherals might not do so - I imagine most smartphones will at least try, but there's many dumber USB peripherals that won't.
    • In the case of a hub connected to a USB power supply without a proper host, it might not work at all.
    • Negotiation is as follows:
      • Each peripheral is permitted to draw one unit load without negotiation. Each peripheral should communicate with the host to request more units.
      • USB 1.1 and 2.0 define one unit load as 100 mA, with a max of 5 unit loads (500 mA).
      • USB 3.0 defines one unit load as 150 mA, with a max of 6 unit loads (900 mA).
  • Modern devices often need more power - smartphones often draw 1000 mA - 2000 mA.
    • There's a battery charging specification that deals with this. See https://www.pericom.com/support/technical-articles/how-usb-charges-just-about-any-electronic-device/ for details on how its negotiation and detection works, but that's not too important.
      • The charging limit is 1500 mA, but only if the data lines are shorted together (or respond as if they have been). This is not the case with a data-capable host like a USB hub. There's an additional profile that deals with this, but a USB 1.1 hub probably does not implement it.
        • Practically, with a non-compatible host most smarter peripherals will fail to detect a high-capacity source and will therefore fall back to charging at 500 mA max. This means your USB hub will likely charge significantly slower than plugging the peripheral directly into the charger.
    • There are some other specs (e.g. Apple's protocol, Qualcomm's quick charge protocol, etc.). They all have their own detection and negotiation methods. They also will not occur with a USB 1.1 hub.
    • There's a newer USB Power Delivery spec, but it deals with all sorts of wacky things like different voltages. Again, with a USB 1.1 hub none of that applies.
  • I wonder if there would have been any problem with defining the USB spec to say that if the supply is between 5.0 and 5.5 volts, any device is allowed to draw up to (V-5V)*5 amps provided that its current demand doesn't increase faster than a certain rate, and provided that its current demand will be immediately reduced if the voltage falls? All one would need to make that would be a power supply whose output voltage would fall as it approached its current limit, which is something many supplies do naturally. – supercat Mar 28 '15 at 22:23
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    @supercat In that case the hub would have to be specifically designed to deny extra power, and of course any hub designed before this new specification wouldn't do that. Some of those hubs would handle it fine, some would handle it but get excessively hot, and some would burst into flames. – user20574 Mar 29 '15 at 1:23
  • I use a USB HUB to charge both my cellphones and it works great. I use it for over 2 years. So far, no fires! I also have an old webcam connected to it, and I use it as a lamp. Still works fine! The cellphone can manage to pull 400mA from it. I have a white brand charger (probably chinese) that I bough on Worten and a Lifetech HUB. – Ismael Miguel Mar 29 '15 at 2:04
  • @user20574: My wondering was about what would have happened if something such as described had been in the spec from the get-go. While some power-supply designs will respond to an excessive current demand by overheating while remaining in regulation, many common topologies will "naturally" sag under such cases, and most supply topologies can be made to sag under such cases by limiting their range of feedback. A switching supply that is limited to 5.2 watts and 5.2 volts, for example, will supply 5.2 volts at 1.0 amps, or 5.0 volts at 1.04 amps. – supercat Mar 29 '15 at 17:25
  • @supercat As the answer already stated, a lot of USB hubs don't have their own power regulation. They just connect the output power lines directly to the input power lines, so all they do is add a negligible amount of resistance, and dissipate some power (from current flowing through that resistance). They don't control the voltage. – user20574 Mar 29 '15 at 21:14
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You can use it to recharge your gadgets, but an old USB1 hub will only output max 500mA per port (according to the specs) and that means very long charging times. Additionally, newer devices won't even charge when connected to such low power connectors. But you may give it a try.

  • I tried my setup and it appears to work. My old Android phone is charging at least. – user1049697 Mar 28 '15 at 10:14
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    Most basic hubs don't really bother with power control - they simply pass the power lines straight through. USB max current draw is primarily something the peripheral should respect, not the host. Also, according to spec the max is actually 100mA without negotiation (one unit load in USB 1.1 and 2.0 is 100mA, max 5 unit loads after negotiation). Also, 500mAh is just wrong - the mAh unit measures capacity, not rate. – Bob Mar 28 '15 at 12:55
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TLDR: maybe, but you probably shouldn't.

I tested this out, not terrifically scientifically. I used my phone - a moto G (the original model X1033) and an app called ampere as my measurement device. I used a second phone (an old HTC one V) as a second 'load'. I only measured one device, with the HTC one V just to see what happens. I've put what the reading on ampere was once the current reading had mostly stabilised.

My USB 1.1 hub was generic, and I tested with a xiaomi charger (Rated to 1A 5V) and powerbank (Rated to 1A and 16000mAH at 3.75V and 10800 at 5V), and the "charging" socket from a Thinkpad x220. I used a powered usb hub from a Roccat Apuri since it was on my desk (Well all of these were!).

As a baseline, a 500mA 5V charger that came with my moto H output up to 490mA according to ampere.

I used the cable from the powerbank for the moto G and another cable for the second device - both are known good, and tend to be reliable cables for charging from both on device USB ports.

There's no 2 device with hub reading for the battery bank - it refused to charge the phone till I unplugged everything when I tried that.

+==========================+========+==============+===============================+
|          Source          | Moto G | Moto G + Hub | Moto G + Hub (with HTC One V) |
+==========================+========+==============+===============================+
| 16000mAH Xiomi Powerpack | 1000mA | 520Ma        | ERR                           |
+--------------------------+--------+--------------+-------------------------------+
| 1A Xiaomi charger        | 980mA  | 380mA        | 360mA                         |
+--------------------------+--------+--------------+-------------------------------+
| x220 charging port       | 360mA  | 330 mA       | 220mA                         |
+--------------------------+--------+--------------+-------------------------------+

The powered USB tests didn't involve the unpowered USB, since... I kinda wasn't bothered. I'd expect to behave like the laptop did.

+==========================+========+====================+
|          Source          | Moto G | Moto G + HTC One V |                         
+==========================+========+====================+
|       Powered USB        |  360Ma |       360Ma        | 
+--------------------------+--------+--------------------+

The powered hub was at 360Ma, but since it's a powered hub, the second device has no effect on the Moto G's rate of charging. For multiple devices this is the most consistent, but this doesn't use the USB 1.1 hub at all!

In short? Not a great idea. At a pinch? Plausible, but wierd stuff could happen.

Practically? You're better off buying a decent powered hub than using a unpowered hub with a wall plug - Its about as complex as the setup you envision, probably easier to set up in a sane manner (USB hubs have SHORT cables), and I'm getting a consistent 360Ma (as with the x220) regardless of what I have plugged in.

  • USB specifications wouldn't allow over 500mA current draw. – David Refoua Feb 2 '16 at 23:22
0

Yes. I use a simple USB hub I bought in the $5 store to charge my Galaxy 5 and Charge HR at the same time. It works fine but won't charge my tablet.

  • @Twisty What? The question is "can I connect a USB 1.1 hub to a wall outlet and charge devices?" and you make an edit summarized as "rephrased to be an answer" that makes the answer say "Yes. /.../ It works fine but won't charge my tablet."? Not that the answer originally was much more helpful but as it stands, it's just plain confusing. – a CVn Jun 12 '15 at 19:07
  • @MichaelKjörling I completely agree this is a minimal attempt at an answer, but since the poster did attempt to answer the question I shored up his phrasing. Feel free to flag or downvote. – Twisty Impersonator Jun 12 '15 at 19:15

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