You are correct in not using the battery -ve if it has the battery monitor attached.
Where is your RSCDC30? Where have you connected the leisure battery -ve?
My RSCDC30 is under the driver's seat so I use the earth stud that is located on the floor under that seat, that is also where my leisure batteries (I have two, one under the seat and one in the furniture) are earthed. Usual rule of thumb, keep the cables as short as possible and of sufficient thickness.
Rod
Where is your RSCDC30? Where have you connected the leisure battery -ve?
My RSCDC30 is under the driver's seat so I use the earth stud that is located on the floor under that seat, that is also where my leisure batteries (I have two, one under the seat and one in the furniture) are earthed. Usual rule of thumb, keep the cables as short as possible and of sufficient thickness.
Rod