To encrypt manually Non OS - Fixed drive, in our case D: partition, these two command should be used:
manage-bde –on D: -RecoveryPassword
manage-bde –autounlock –enable D:
First command starts encryption of D: partition and write Recovery password in AD.
Second command enables autounlock of D: partition.
There is no need to wait encryption to finish to execute the second command.
To write Recovery password in AD requirement is to have GPO for BitLocker configured.