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MIcro USB "charger" cables — Parallax Forums

MIcro USB "charger" cables

Peter JakackiPeter Jakacki Posts: 10,193
edited 2014-02-20 15:45 in General Discussion
I use micro USB connectors and cables a lot in my projects but a lot of times they are also used to power the device and in this respect there doesn't seem to be any standards. I have boxes of cables that are useless for this purpose, if you strip them back you find that the "wire" is in fact a single sub-millimetre wide foil that is wrapped around the flex thread, a bit like earphone cable.

So in my determination to find out which ones were good and which ones were bad I just devised a standard test of plugging them into one of my little "Proplink" compatible plugs and since I have the USB 5V on the end connector I used a 22R resistor for a load of around 230ma at the charger reference of 5.25V.

I have a short thick cable that came with my Nexus 7 I think and if I plug that in I still read 5.2V at the load end. Another good cable read 5.05V etc. Most of the cables however read 4.37V and that would be at less current of course. These ones I have thrown in the bin, there are a lot of them. Though I could use them for signal cables it is too confusing to have them around.

Now the trouble with purchasing cables esp. on Ebay is that there is no reference figure that's used to describe their conductance. I'm using the voltage under the 22R load as my figure, it's conservative but indicative enough for my purposes. Does anyone know of any good "charger" style cables that I can purchase in bulk at a good price? I normally just use 1M cables.

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