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I've been searching around for a splitter-type / octopus device that will let me charge many (8) devices over micro-usb from a single outlet. My assumption has been (but correct me if I'm wrong) that just stringing together splitters won't get me anywhere, since the ac-to-dc converter off the wall will have a fixed current, so the power will just be divided between the devices, hence no faster than just charging the devices in series. If designed to charge many devices at once though, ample current could be drawn for each micro-usb connection.

Since I haven't found anything yet, it has me wondering:

  1. Have I just missed something in my search?
  2. If not, am I misunderstanding something in this picture?
  3. If not, is there just no market for such a device?
  4. And if this last one is the case, how difficult does it sound to build this?
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  • \$\begingroup\$ a charger may be using a "handshaking" protocol with the device to determine optimal charging current .... connecting multiple devices to the charger port will confuse the charger and result in minimal charging current or no current at all ...... you can buy multi-port chargers \$\endgroup\$
    – jsotola
    Commented May 20, 2018 at 5:33
  • \$\begingroup\$ In addition to the above, a standard single-port charger won't deliver above 10W. So the sum of connected devices won't be able to draw more than that. \$\endgroup\$
    – SomeoneSomewhereSupportsMonica
    Commented May 20, 2018 at 10:13

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so the power will just be divided between the devices

Much worse: Most devices just draw their charging current, overloading the (usually cheap) USB wall wart until it burns or blows up.

This is a huge no-go, hence why there should be no USB cables like that available anywhere.

Note that there are multi-port chargers available that can support 1 or 2A on each port even when all ports are used in parallel. A multi-socket extension cord is usually cheaper, though.

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  • \$\begingroup\$ Great point, thanks for the warning! I didn't make an important distinction in my original post which maybe changes things a little. I don't envision a USB-A to 8xUSB-micro octopus that would just plug into any USB wall wart. The ideal product I had in mind just had 8 micro-usb cables sprouting from a single ac-to-dc converter that could draw larger currents from the wall. Maybe per the usb spec or otherwise this doesn't exist either. \$\endgroup\$
    – fedora
    Commented May 20, 2018 at 20:52
  • \$\begingroup\$ The analogous workaround is a device like this or this which I would then just plug 6 or 8 USB-A to USB-micro cables into. This solution is functionally great, it's only that space is at a premium for this project and all those ports and extra connections seemed like a waste given my use case will always be the same USB-micro outputs. \$\endgroup\$
    – fedora
    Commented May 20, 2018 at 20:55
  • \$\begingroup\$ You have to get rid of about 80W of heat for 8x 5V * 2A. This will either requirer a fan or a certain volume for cooling. \$\endgroup\$
    – Turbo J
    Commented May 21, 2018 at 7:20

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