Question about Samsung Portable SSD T3

When the SSD T3 is only plugged in, it needs practically no power. If I copy a large file, then the power consumption on my Surface 2 increases from 8 watts to about 16 W. If a large file is copied internally, the power consumption increases to about 13 W. This means that the SSD needs about 3 watts when reading/writing, and almost nothing else.