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I am using a RPI3 and have a GPS USB module and 3g USB dongle connected to the USB ports of the pi. I am using a 5 volts, 2.4 amps power supply. I was wondering if the RPI3 USB ports provide 1.2 Amps by default or only 600mA per port ? Because sometimes when initially powering up the system, wvdial fails (ppp dies, exit code:10), and then I reboot and it works. This keeps happening randomly.

If the rpi3 USB port provides only 600mA by default, is there a way to increase it to 1.2 amps in the software ?

Or do I have to just use a USB powered hub or just connect a y cable to 2 ports of the Pi and the 3g dongle ?

  • @Ghanima I do no have enough reputation to post there. So, it is mentioned in the page that the rpi3 by default has high current setting. If so, how much is that ? – bobdxcool Oct 4 '16 at 16:11
  • 1.2 A total; I don't think the ports have a limitation beyond that, i.e., in theory you could draw 800 mA from one and 400 mA from another. Which should cover your GPS adapter. If your supply involves a microUSB cable, try a different cable. Also: Does the red power LED flicker? – goldilocks Oct 4 '16 at 16:17
  • @goldilocks Red LED flickers sometimes randomly. Mostly during initial power up. So in case my (for example)GPS is drawing 800 mA, then only 400 mA is available for my 3g dongle which might not be sufficient during low signals. So, a powered hub is needed ? – bobdxcool Oct 4 '16 at 16:22
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    @goldilocks, here, have your Precision Verbosity badge ;) – Ghanima Oct 4 '16 at 17:02
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See Raspberry Pi Power Limitations for detail of the Pi3 power.

NOTE the Pi3 SHOULD be able to power, but my experience indicates this is not so. It is a combination of PSU which don't actually supply the correct voltage, thin USB power cable and internal voltage drops.

Your problem is probably NOT that the PSU cannot provide the current, but the voltage is too low. Many phone "chargers" do not supply 5V, and are permitted to drop to 3.6V which is adequate for phone charging.

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    Wouldn't that be around 4.6V, that is, +/-10%? – TheDiveO Jul 26 '17 at 5:31

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