USB A power output

Hi all,

I am having difficulty getting above 500mA directly from the USB A port with the majority of my devices.

The only devices I have that can exceed 500mA directly connected to the laptop are my bicycle torch which draws 1A flat, my cooling pad which draws 620mA (before killing the port minutes later) and my old 2.5" external HDD which can spike to ~600mA briefly but idles around 200mA.

The strange thing is when passed through my 4 port USB 3.0 hub (still using USB 2.0 charging cables) they work as expected and combined I have got over 2.3A from one port this way so the port is capable.

Any suggestions appreciated.

Each port can supply up to 3A, but only 2 ports at a time can do 3A and the other 2 do 1.5A, how are you getting these measurements and why do you think you cannot get more than 500mA, and what is the expected behavior?

500mA is the spec limit when the data lines are connected (i.e not shorted)

Heaps of devices use above the spec.

Hi, I’m using a USB tester to measuring the current draw.

Even removing the USB tester from the equation I can tell from the charge rate it is not delivering more than 500mA.

Expected behaviour is in the case of my phone 1A, my tablet 1.5A. I get these from an old macbook pro with USB 3.0 and when I run the devices through a USB 3.0 hub.

sure, and when something doesn’t work its the fault of the device for drawing more power than its allowed, not the source.

What do you make of this?

third line, 500mA. That’s the limit for pre-USB3 power and data. higher power (1.5A) is available by shorting the data lines.

So what is going on in your estimation with the macbook and the USB hub with the FW? Why am I able to charge at higher than the spec? My post was to find out how can I achieve the same desired behaviour of my old machine.

No offence I’m but I’m looking for solutions to my issue not a lesson on how devices should be following the USB spec. If you are able to help with that that would be great.

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