Stand-alone the colorimeter is powered by 4 AA batteries (supplied). The
power switches off after 2 minutes (Mystrica 2.0, 30 seconds with older versions) to conserve the batteries unless the unit is connected to a PC, tablet or phone. The calibration
values are retained so you just need to press the power switch again to continue working.
When the unit is connected through the USB cable suppled to either a PC or to a mains USB socket the power is drawn through the cable, the unit stays on permanently and the batteries are conserved.