USB Cable Testing

As is common I have accumulated a lot of USB cables over the years. After having trouble with one of them I decided it was time to test them all. There seems to be several different approaches to this, but I decided supply the cable with the usual 5V supply and put a 100 ohm power resistor on the other end as load. I am not sure if this is very accurate, but it should be good enough to filter out good and bad cables.

My modular approach involved the resistor with soldered connectors to be used with Mini-USB and Micro-USB breakout boards:

I measured the 5V source to actually be around 5.09V. Nearly all of the cables are of unknown origin, so only the length is and measure voltage are listed.

Micro-USB:
* 300cm = 4.95V
* 200cm = 5.06V
* 120cm = 5.04V
* 100cm = 5.07V
* 33cm = 5.06V
* 32cm = 5.04V
* 32cm = 5.07V

Mini-USB:
* 120cm = 5.05V
* 80cm = Broken!
* 80cm = 4.91V
* 73cm = 4.82V
* 57cm = 5.07V
* 44cm = 5.07V
* 44cm = 5.07V
* 31cm = 5.08V
* 28cm = 5.04V
* 22cm = 5.08V

As expected from the Micro-USB cables, the 3m cable had quite a large voltage drop, but I was surprised about the 2m cable giving such good results. Among the Mini-USB ones there was one broken and two pretty poor ones that fell below 5.00V. Those will go to the recycler.