The development boards can be powered either from PC USB port or from an external power supply.

Generally PC USB current is limited to 50 mA. If the demoboard enumerates as USB device, you can increase its power consumption up to 500 mA (the current limit is specified in the USB device descriptors).

External power supply can be connected either to the on-board USB connector or to the J3 connector. By default J3 connector is not assembled and you would need to solder it yourself.

The RTC (Real-Time Clock) has a separate power domain. This power domain can be connected to the battery (not mounted on the board) through J2 connector.