Ducati Monster 821 Owner's Manual page 200

Connect the positive pole of the external device to
the battery positive pole (3).
Connect the negative pole of the external device to
engine mounting screw (4), after removing both
covers on engine LH side.
To remove the covers, refer to "Removing the battery"
page 202.
Warning
When connecting the positive pole of the
external device to the positive pole (3) of the battery,
pay utmost attention not to touch any other metal
parts on the vehicle.
3
4
Fig. 128
Fig. 129
199