USB Powered mains plug?

[gmc]

I've got a USB keyboard connected to my pi.

I notice when I plug my pi into the PC via a microusb cable the keyboard works and the nic works.

If I power the pi via my HTC usb charger (Rated at 1A) , my Apple USB charger (Rated 0.45A) the keyboard does not work and the nic lights do not come on either.

Any ideas why? The 1A plug should have more than enough power for both the keyboard and the nic?

[gmc]

Problem solved.

I used my HTC cable and it works fine. I then tried 2 cables I got off ebay (which work fine with my phone)

I measured the voltage at the 5V point and it was 4V. The crappy usb cables must have a higher resistance - cheap cable!

I've chopped the cable off and used some decent multicore cable and now the voltage is 4.9V. Everything working perfectly now.

Beware of the cheap usb cable!!!