I decided to test the charge rate of my Nexus devices, I have a Nexus 10, Nexus 7 (2012) Nexus 5 and Galaxy Nexus. I have a Nexus 1 but I couldnt be bothered booting it.
Tests were done using a 5v source from an old ATX power supply, so it has 30 Amps at 5V to play with.
All devices are running android 5.0.X except the Galaxy Nexus which is running a recent Cyanogen Mod Android 4.3
Some odd things, at times the N7 would decide to draw practically nothing, seemed rather random. It though through its pogo pin by far drew the most power at 1.2 amps. The N10 was a little surprising, it seemed to think that the USB mode was AC and would draw more power than actual AC mode did. Its Magnetic POGO didn’t seem to provide that much power. I would have expected something with large pins would take more than 1 Amp, since its charger is 2 Amp rated. I guess this is why Google/Samsung never got the charging right. The Nexus 5 was a little disappointing in that it drew very little more power on AC Mode.
We cant expect much really through micro USB, the wires are so small on the connector and on the circuits behind them, they really are not capable of carrying much.