On Tue, 12 Mar 2013, Toby Corkindale <toby.corkindale@strategicdata.com.au> wrote:
Seconded. I have had a nightmare month or two of failing USB cables, and new cables which can't actually push full power through themselves. I suspect this is partly because I went around upgrading my USB power sources from 500-1000 mA to 1000-2000 mA units, which is well above the original USB spec.. but yet now quite common for charging phones and driving embedded boards.
I'm currently having some success with 30cm micro-usb cables from Korea that seem to work fine. I also have some $10 cables from Jaycar which are annoyingly long (1.8m) but which otherwise seem to be built well enough to carry power.
http://etbe.coker.com.au/2013/01/24/power-supplies-wires/
I've done some calculations about the resistance of wires for USB chargers. I had to make some assumptions about the thickness of the conductors in the cables, but anyone who's interested can make their own calculations with different assumptions.
Is there anything you haven't blogged about? The USB3 cable I was using originally (the ~1.5M length one) was about the thickness of a 10A 240V power cable, although that's the outside diameter and I don't want to cut it open to find out the diameter of the wires inside. The one I'm using now is about 20cm long and is much thinner. I'm more interested in getting readings from the USB controller about the power budget and the draws of the attached devices (even though these are programmed values not actual values) in an easy to read form. James