Scenario: A smartphone (Nexus S) battery is charged via USB connection, connected with a laptop. A measuring device (USB Tester) is running between laptop and smartphone.
Observation: The measured current and voltage while charging battery is - more or less -constant. After the battery is charged, the current drops to zero. This is the expected behavoir, but here it comes: After using the charged phone a few seconds, although the phone shows a "battery charged" status, the measured current rises again. It is not constant, but depends on the screen status, cpu load, apps running etc.
Question: Is this state - variable current, depending on actions taken on the smartphone - a direct measurement of the smartphone power consumption? Or do you have another idea what is causing this phenomenon?