The DC Power port is a Female 3-Pin Mini XLR Jack which supports both DC power in and DC Power Out. 

DC In	11 - 15 V (5 A)	Max 75 W
DC Out	11-16.8 V (2.4 A fuse)	25W @ 11 V (Empty internal battery) 40W @ 16.8 V (Full internal battery and AC power supply)

When DC OUT is enabled then the current voltage of the internal batteries will be sent out continuously. 

Pin 1	Pin 2	Pin 3
DC IN	GND	DC OUT