The connector is a little different from the picture, the pin order is the same.
|Description (may be empty)|
|1||6,8vdc||0,625Ah (only for charging, I think)|
|2||12vdc (?!)||Not present in the power supply label (maybe not necessary).|
|4||GND||The metal ring around the pins is connected with GND, same as pin 4.|
The power supply label indicates +5v and +6,8v, but I could measure even a +12v in pin 2.