The list of the board that RTC circuit implement:
ODROID-HC1 / ODROID-HC2
ODROID-XU4
ODROID-C1 / ODROID-C1+
ODROID-U3
ODROID-XU / XULite
Specification
Coin Cell : CR2032 3Volt/220mAH
Wire : 70mm
Connector : Molex 51021-0200 compatible (1.25mm pitch)
Battery weight 2.7 grams
*Cable connection. Note that the red wire is Positive pole and the black wire is Negative pole.