Is it possible to use the tablet battery first, and then the docking station?

Question

Batteries

Is it possible to use the tablet's battery first, and then only the docking stations in windows? The asus convertible netbook has a battery in the tablet and in the keyboard dock. When the charge is low, the keyboard starts to turn off (departs), so I would like to use the tablet battery first, but I did not find in the settings where the order of using the batteries is.